Angina Pectoris

Practice Essentials

Angina pectoris is the result of myocardial ischemia caused by an imbalance between myocardial blood supply and oxygen demand. It is a common presenting symptom (typically, chest pain) among patients with coronary artery disease (CAD). Approximately 9.8 million Americans are estimated to experience angina annually, with 500,000 new cases of angina occurring every year. Signs and symptoms Patients should be asked about the frequency of angina, severity of pain, and number of nitroglycerin pills used during episodes. Symptomatology reported by patients with angina commonly includes the following:

• Retrosternal chest discomfort (pressure, heaviness, squeezing, burning, or choking sensation) as opposed to frank pain

• Pain localized primarily in the epigastrium, back, neck, jaw, or shoulders

• Pain precipitated by exertion, eating, exposure to cold, or emotional stress, lasting for about 1-5 minutes and relieved by rest or nitroglycerin

• Pain intensity that does not change with respiration, cough, or change in position

Angina decubitus (a variant of angina pectoris that occurs at night while the patient is recumbent) may occur.

The following should be taken into account in the physical examination:

• For most patients with stable angina, physical examination findings are normal

• A positive Levine sign suggests angina pectoris

• Signs of abnormal lipid metabolism or of diffuse atherosclerosis may be noted

• Examination of patients during the angina attack may be more helpful

• Pain produced by chest wall pressure is usually of chest wall origin

Diagnosis Diagnostic studies that may be employed include the following:

• Chest radiography: Usually normal in angina pectoris but may show cardiomegaly in patients with previous MI, ischemic cardiomyopathy, pericardial effusion, or acute pulmonary edema

• Graded exercise stress testing: This is the most widely used test for the evaluation of patients presenting with chest pain and can be performed alone and in conjunction with echocardiography or myocardial perfusion scintigraphy

• Coronary artery calcium (CAC) scoring by fast CT: The primary fast CT methods for this application are electron-beam CT (EBCT) and multidetector CD (MDCT)

Other tests that may be useful include the following:

• ECG (including exercise with ECG monitoring and ambulatory ECG monitoring)

• Selective coronary angiography (the definitive diagnostic test for evaluating the anatomic extent and severity of CAD)

Management General treatment measures include the following:

• Encouragement of smoking cessation

• Treatment of risk factors (eg, hypertension, diabetes mellitus, obesity, hyperlipidemia)

In patients with CAD, efforts should be made to lower the low-density lipoprotein (LDL) level (eg, with a statin). Current Adult Treatment Panel III (ATP III) guidelines are as follows [1] :

• In high-risk patients, a serum LDL cholesterol level of less than 100 mg/dL is the goal

• In very high-risk patients, an LDL cholesterol level goal of less than 70 mg/dL is a therapeutic option

• In moderately high-risk persons, the recommended LDL cholesterol level is less than 130 mg/dL, but an LDL cholesterol level of 100 mg/dL is a therapeutic option

• Non-high-density lipoprotein (HDL) cholesterol level is a secondary target of therapy in persons with high triglyceride levels (>200 mg/dL); the goal in such persons is a non-HDL cholesterol level 30 mg/dL higher than the LDL cholesterol level goal

Patients with established CAD and low HDL levels are at high risk for recurrent events and should be targeted for aggressive nonpharmacologic and pharmacologic treatment. The currently accepted management approach is as follows:

• In all persons with low HDL cholesterol levels, the primary target of therapy is to achieve the ATP III guideline LDL cholesterol level goals with diet, exercise, and drug therapy as needed

• After the targeted LDL level goal is reached, emphasis shifts to other issues; in patients with low HDL and high triglyceride levels, the secondary priority is to achieve the non-HDL cholesterol level goal (30 mg/dL higher than the LDL goal); in patients with isolated low HDL cholesterol levels and triglyceride levels below 200 mg/dL, drugs to raise HDL can be considered

Other pharmacologic therapies that may be considered include the following:

• Enteric-coated aspirin

• Clopidogrel

• Hormone replacement therapy

• Sublingual nitroglycerin

• Beta blockers

• Calcium channel blockers

• Angiotensin-converting enzyme (ACE) inhibitors

• Injections of autologous CD34+ cells [2]

Revascularization therapy (ie, coronary revascularization) can be considered in the following:

• Patients with left main artery stenosis greater than 50%

• Patients with 2- or 3-vessel disease and left ventricular (LV) dysfunction

• Patients with poor prognostic signs during noninvasive studies

• Patients with severe symptoms despite maximum medical therapy

The 2 main coronary revascularization procedures are (1) percutaneous transluminal coronary angioplasty, with or without coronary stenting, and (2) coronary artery bypass grafting. Considerations for choosing a procedure include the following:

• Patients with 1- or 2-vessel disease and normal LV function who have anatomically suitable lesions are candidates for percutaneous transluminal coronary angioplasty and coronary stenting.

• Drug-eluting stents can remarkably reduce the rate of in-stent restenosis

• Patients with significant left main coronary artery disease, 2- or 3-vessel disease and LV dysfunction, diabetes mellitus, or lesions anatomically unsuitable for percutaneous transluminal coronary angioplasty have better results with coronary artery bypass grafting

Other procedures that may be considered include the following:

• Intra-aortic balloon counterpulsation (in patients who continue to have unstable angina pectoris despite maximal medical treatment): This should be followed promptly by coronary angiography with possible coronary revascularization [3]

• Enhanced external counterpulsation (in patients whose angina is refractory to medical therapy and who are not suitable candidates for either percutaneous or surgical revascularization) [4]

• Laser transmyocardial revascularization (experimental) [5]

• Use of the Coronary Sinus Reducer (Neovasc Medical, Inc, Or Yehuda, Israel), a percutaneous implantable device designed to establish coronary sinus narrowing and elevate coronary sinus pressure (further studies needed)

Background

Angina pectoris is the result of myocardial ischemia caused by an imbalance between myocardial blood supply and oxygen demand. Angina is a common presenting symptom (typically, chest pain) among patients with coronary artery disease. A comprehensive approach to diagnosis and to medical management of angina pectoris is an integral part of the daily responsibilities of health care professionals.

Pathophysiology Myocardial ischemia develops when coronary blood flow becomes inadequate to meet myocardial oxygen demand. This causes myocardial cells to switch from aerobic to anaerobic metabolism, with a progressive impairment of metabolic, mechanical, and electrical functions. Angina pectoris is the most common clinical manifestation of myocardial ischemia. It is caused by chemical and mechanical stimulation of sensory afferent nerve endings in the coronary vessels and myocardium. These nerve fibers extend from the first to fourth thoracic spinal nerves, ascending via the spinal cord to the thalamus, and from there to the cerebral cortex. Studies have shown that adenosine may be the main chemical mediator of anginal pain. During ischemia, ATP is degraded to adenosine, which, after diffusion to the extracellular space, causes arteriolar dilation and anginal pain. Adenosine induces angina mainly by stimulating the A1 receptors in cardiac afferent nerve endings. [6] Heart rate, myocardial inotropic state, and myocardial wall tension are the major determinants of myocardial metabolic activity and myocardial oxygen demand. Increases in the heart rate and myocardial contractile state result in increased myocardial oxygen demand. Increases in both afterload (ie, aortic pressure) and preload (ie, ventricular end-diastolic volume) result in a proportional elevation of myocardial wall tension and, therefore, increased myocardial oxygen demand. Oxygen supply to any organ system is determined by blood flow and oxygen extraction. Because the resting coronary venous oxygen saturation is already at a relatively low level (approximately 30%), the myocardium has a limited ability to increase its oxygen extraction during episodes of increased demand. Thus, an increase in myocardial oxygen demand (eg, during exercise) must be met by a proportional increase in coronary blood flow. The ability of the coronary arteries to increase blood flow in response to increased cardiac metabolic demand is referred to as coronary flow reserve (CFR). In healthy people, the maximal coronary blood flow after full dilation of the coronary arteries is roughly 4-6 times the resting coronary blood flow. CFR depends on at least 3 factors: large and small coronary artery resistance, extravascular (ie, myocardial and interstitial) resistance, and blood composition. Myocardial ischemia can result from (1) a reduction of coronary blood flow caused by fixed and/or dynamic epicardial coronary artery (ie, conductive vessel) stenosis, (2) abnormal constriction or deficient relaxation of coronary microcirculation (ie, resistance vessels), or (3) reduced oxygen-carrying capacity of the blood. Atherosclerosis is the most common cause of epicardial coronary artery stenosis and, hence, angina pectoris. Patients with a fixed coronary atherosclerotic lesion of at least 50% show myocardial ischemia during increased myocardial metabolic demand as the result of a significant reduction in CFR. These patients are not able to increase their coronary blood flow during stress to match the increased myocardial metabolic demand, thus they experience angina. Fixed atherosclerotic lesions of at least 90% almost completely abolish the flow reserve; patients with these lesions may experience angina at rest. Coronary spasm can also reduce CFR significantly by causing dynamic stenosis of coronary arteries. Prinzmetal angina is defined as resting angina associated with ST-segment elevation caused by focal coronary artery spasm. Although most patients with Prinzmetal angina have underlying fixed coronary lesions, some have angiographically normal coronary arteries. Several mechanisms have been proposed for Prinzmetal angina: focal deficiency of nitric oxide production, [7] hyperinsulinemia, low intracellular magnesium levels, smoking cigarettes, and using cocaine. Approximately 30% of patients with chest pain referred for cardiac catheterization have normal or minimal atherosclerosis of coronary arteries. A subset of these patients demonstrates reduced CFR that is believed to be caused by functional and structural alterations of small coronary arteries and arterioles (ie, resistance vessels). Under normal conditions, resistance vessels are responsible for as much as 95% of coronary artery resistance, with the remaining 5% being from epicardial coronary arteries (ie, conductive vessels). The former is not visualized during regular coronary catheterization. Angina due to dysfunction of small coronary arteries and arterioles is called microvascular angina. Several diseases, such as diabetes mellitus, hypertension, and systemic collagen vascular diseases (eg, systemic lupus erythematosus, polyarteritis nodosa), are believed to cause microvascular abnormalities with subsequent reduction in CFR. The syndrome that includes angina pectoris, ischemialike ST-segment changes and/or myocardial perfusion defects during stress testing, and angiographically normal coronary arteries is referred to as syndrome X. Most patients with this syndrome are postmenopausal women, and they usually have an excellent prognosis. [8] Syndrome X is believed to be caused by microvascular angina. Multiple mechanisms may be responsible for this syndrome, including (1) impaired endothelial dysfunction, [9] (2) increased release of local vasoconstrictors, (3) fibrosis and medial hypertrophy of the microcirculation, (4) abnormal cardiac adrenergic nerve function, and/or (5) estrogen deficiency. [10] A number of extravascular forces produced by contraction of adjacent myocardium and intraventricular pressures can influence coronary microcirculation resistance and thus reduce CFR. Extravascular compressive forces are highest in the subendocardium and decrease toward the subepicardium. Left ventricular (LV) hypertrophy together with a higher myocardial oxygen demand (eg, during tachycardia) cause greater susceptibility to ischemia in subendocardial layers. Myocardial ischemia can also be the result of factors affecting blood composition, such as reduced oxygen-carrying capacity of blood, as is observed with severe anemia (hemoglobin, < 8 g/dL), or elevated levels of carboxyhemoglobin. The latter may be the result of inhalation of carbon monoxide in a closed area or of long-term smoking. Ambulatory ECG monitoring has shown that silent ischemia is a common phenomenon among patients with established coronary artery disease. In one study, as many as 75% of episodes of ischemia (defined as transient ST depression of 1 mm or above persisting for at least 1 min) occurring in patients with stable angina were clinically silent. Silent ischemia occurs most frequently in early morning hours and may result in transient myocardial contractile dysfunction (ie, stunning). The exact mechanism(s) for silent ischemia is not known. However, autonomic dysfunction (especially in patients with diabetes), a higher pain threshold in some individuals, and the production of excessive quantities of endorphins are among the more popular hypotheses. [11]

Etiology Causes of angina pectoris include the following:

• Decrease in myocardial blood supply due to increased coronary resistance in large and small coronary arteries

• Increased extravascular forces, such as severe LV hypertrophy caused by hypertension, aortic stenosis, or hypertrophic cardiomyopathy, or increased LV diastolic pressures

• Reduction in the oxygen-carrying capacity of blood, such as elevated carboxyhemoglobin or severe anemia (hemoglobin, < 8 g/dL)

• Congenital anomalies of the origin and/or course of the major epicardial coronary arteries

• Risk factors

• Precipitating factors

• Preventive factors

Decrease in myocardial blood supply due to increased coronary resistance in large and small coronary arteries Causes of such decreases in myocardial blood supply include the following:

• Significant coronary atherosclerotic lesion in the large epicardial coronary arteries (ie, conductive vessels) with at least a 50% reduction in arterial diameter

• Coronary spasm (ie, Prinzmetal angina)

• Abnormal constriction or deficient endothelial-dependent relaxation of resistant vessels associated with diffuse vascular disease (ie, microvascular angina) [12]

• Syndrome X

• Systemic inflammatory or collagen vascular disease, such as scleroderma, systemic lupus erythematous, Kawasaki disease, polyarteritis nodosa, and Takayasu arteritis

Congenital anomalies of the origin and/or course of the major epicardial coronary arteries These include structural abnormalities of the coronary arteries (congenital coronary artery aneurysm or fistula, coronary artery ectasia, coronary artery fibrosis after chest radiation, coronary intimal fibrosis following cardiac transplantation). Risk factors Major risk factors for atherosclerosis include a family history of premature coronary artery disease, cigarette smoking, diabetes mellitus, hypercholesterolemia, or systemic hypertension. Other risk factors include LV hypertrophy, obesity, and elevated serum levels of homocysteine, lipoprotein (a), plasminogen activator inhibitor, fibrinogen, serum triglycerides, or low high-density lipoprotein (HDL). Metabolic syndrome has been characterized by the presence of hyperinsulinemia (fasting glucose level, ≥100 mg/dL), abdominal obesity (waist circumference, >40 in for men or >35 in for women), decreased HDL cholesterol levels (< 40 mg/dL for men or < 50 mg/dL for women), hypertriglyceridemia (>150 mg/dL), and hypertension (≥130/85 mm Hg). Based on data from the 2000 US census, an estimated 47 million Americans have the metabolic syndrome. Patients with the metabolic syndrome have a 3-fold increased risk for coronary atherosclerosis and stroke compared with those without this syndrome. [13] Precipitating factors These include factors such as severe anemia, fever, tachyarrhythmias, catecholamines, emotional stress, and hyperthyroidism, which increase myocardial oxygen demand. Preventive factors Factors associated with reduced risk of atherosclerosis are a high serum HDL cholesterol level, physical activity, estrogen, and moderate alcohol intake (1-2 drinks/d).

Epidemiology United States statistics Approximately 9.8 million Americans are estimated to experience angina annually, with 500,000 new cases of angina occurring every year. In 2009, an estimated 785 000 Americans will have a new coronary attack, and about 470 000 will have a recurrent attack. Only 18% of coronary attacks are preceded by angina. An additional 195,000 silent first myocardial infarctions are estimated to occur each year. [13] Race-related demographics The annual rates per 1000 population of new episodes of angina for those aged 45-54 years are as follows [13] :

• 8.5 for nonblack men

• 10.6 for nonblack women

• 11.8 for black men

• 20.8 for black women

The annual rates per 1000 population of new episodes of angina for those aged 55-64 years are as follows [13] :

• 11.9 for nonblack men

• 11.2 for nonblack women

• 10.6 for black men

• 19.3 for black women

The annual rates per 1000 population of new episodes of angina for those aged 65-74 years are as follows [13] :

• 13.7 for nonblack men

• 13.1 for nonblack women

• 8.8 for black men

• 10.0 for black women

Sex-related demographics Angina pectoris is more often the presenting symptom of coronary artery disease in women than in men, with a female-to-male ratio of 1.7:1. It has an estimated prevalence of 4.6 million in women and 3.3 million in men. In one analysis, this female excess was found across countries and was particularly high in the American studies and higher among nonwhite ethnic groups than among whites. [14] The frequency of atypical presentations is also more common among women compared with men. Women have a slightly higher rate of mortality from coronary artery disease compared with men, in part because of an older age at presentation and a frequent lack of classic anginal symptoms. The estimated age-adjusted prevalence of angina is greater in women than in men. Age-related demographics The prevalence of angina pectoris increases with age. Age is a strong independent risk factor for mortality. More than 150,000 Americans killed by CVD in 2005 were younger than 65 years. However, in 2005, 32% of deaths from cardiovascular disease occurred before the age of 75 years, which is well before the average life expectancy of 77.9 years. [13]

Prognosis Important prognostic indicators in patients with angina pectoris include LV function, severity and location of atherosclerotic lesions, and response of symptoms to medical treatment. LV function is the strongest predictor of long-term survival. Elevated LV end-diastolic pressure and volume along with reduced LV ejection fraction ( (< 40%) are poor prognostic signs. Note the following:

• Critical lesions of left main and proximal left anterior descending coronary arteries are associated with a greater risk. Mortality rates are also directly associated with the number of epicardial arteries involved.

• Unstable angina, recent MI, or both is a sign of atherosclerotic plaque instability, which is a strong predictor of increased risk of short-term coronary events.

More recent studies indicate that epicardial adipose tissue thickness (EAT) can also be used to predict major adverse cardiac events. [15] In a study of 200 patients hospitalized with stable angina pectoris, unstable angina pectoris, or acute myocardial infarction who underwent coronary angiography, patients with a baseline EAT of more than 7 mm suffered significantly more revascularizations, nonfatal myocardial infarction, and cardiovascular death. [15] A number of signs during noninvasive testing are predictive of a higher risk of coronary events, including ST-segment depression of more than 2 mm at a low workload, ST-segment depression that persists for more than 5 minutes after termination of exercise, and failure of blood pressure to rise or an actual drop in blood pressure. Patients who continue to smoke after an MI have a 22-47% increased risk of reinfarction and death. In general, Prinzmetal angina and syndrome X are associated with excellent long-term prognoses. Morbidity/mortality About every 25 seconds, an American will have a coronary event, and about every minute someone will die from one. Coronary heart disease (CHD) caused about 1 of every 5 deaths in the United States in 2005. Final 2005 coronary heart disease mortality in 2005 was 445,687 (232,115 males and 213,572 females). On the basis of 2005 mortality rate data, nearly 2,400 Americans die of cardiovascular disease (CVD) each day—an average of 1 death every 37 seconds. The 2006 overall preliminary death rate from cardiovascular disease was 262.9. [13] Complications Complications of angina pectoris include unstable angina, MI, and death.

Clinical Presentation

History Most patients with angina pectoris report of retrosternal chest discomfort rather than frank pain. The former is usually described as a pressure, heaviness, squeezing, burning, or choking sensation. Anginal pain may be localized primarily in the epigastrium, back, neck, jaw, or shoulders. Typical locations for radiation of pain are arms, shoulders, and neck. Typically, angina is precipitated by exertion, eating, exposure to cold, or emotional stress. It lasts for approximately 1-5 minutes and is relieved by rest or nitroglycerin. Chest pain lasting only a few seconds is not usually angina pectoris. The intensity of angina does not change with respiration, cough, or change in position. Pain above the mandible and below the epigastrium is rarely anginal in nature. Ask patients about the frequency of angina, severity of pain, and number of nitroglycerin pills used during angina episodes. Angina decubitus Angina decubitus is a variant of angina pectoris that occurs at night while the patient is recumbent. Some have suggested that it is induced by an increase in myocardial oxygen demand caused by expansion of the blood volume with increased venous return during recumbency.

Physical Examination For most patients with stable angina, physical examination findings are normal. Diagnosing secondary causes of angina, such as aortic stenosis, is important. A positive Levine sign (characterized by the patient's fist clenched over the sternum when describing the discomfort) is suggestive of angina pectoris. Look for physical signs of abnormal lipid metabolism (eg, xanthelasma, xanthoma) or of diffuse atherosclerosis (eg, absence or diminished peripheral pulses, increased light reflexes or arteriovenous nicking upon ophthalmic examination, carotid bruit). Examination of patients during the angina attack may be more helpful. Useful physical findings include third and/or fourth heart sounds due to LV systolic and/or diastolic dysfunction and mitral regurgitation secondary to papillary muscle dysfunction. Pain produced by chest wall pressure is usually of chest wall origin.

Differential Diagnoses

Diagnostic Considerations

In patients with stable angina pectoris, even the most carefully performed history and physical examination have limitations. Classification of these patients solely on the basis of history and physical examination findings may lead to serious mistakes. Some type of stress testing is usually indicated to confirm the diagnosis and quantitate the severity of ischemia.

In women, elderly persons, and diabetic patients, coronary artery disease may manifest with atypical presentations other than angina pectoris, such as silent ischemia or infarction. Clinicians should use a careful approach when evaluating these patients.

Other conditions to consider in patients with suspected coronary artery disease include the following:

• Esophageal spasm

• Esophageal rupture

• Costochondritis

• Herpes zoster

• Pneumonia with pleural involvement

Differential Diagnoses

• Acute Gastritis

• Acute Pericarditis

• Anemia

• Anxiety Disorders

• Aortic Dissection

• Aortic Stenosis

• Biliary Colic

• Acute Cholecystitis

• Cocaine Toxicity

• Coronary Artery Atherosclerosis

• Coronary Artery Vasospasm

• Familial Hypercholesterolemia

• Gastroesophageal Reflux Disease

• Hiatal Hernia

• Hypertension

• Hyperthyroidism and Thyrotoxicosis

• Hypertrophic Cardiomyopathy

• Isolated Coronary Artery Anomalies

• Kawasaki Disease

• Mitral Regurgitation

• Mitral Valve Prolapse

• Panic Disorder

• Peptic Ulcer Disease

• Physical Medicine and Rehabilitation for Systemic Lupus Erythematosus

• Pleurodynia

• Pneumothorax Imaging

• Polyarteritis Nodosa

• Polygenic Hypercholesterolemia

• Pott Disease (Tuberculous [TB] Spondylitis)

• Idiopathic Pulmonary Arterial Hypertension

• Pulmonary Embolism (PE)

• Scleroderma

• Pulmonary Arterial Hypertension

• Takayasu Arteritis

• Type 1 Diabetes Mellitus

• Type 2 Diabetes Mellitus

• Varicella-Zoster Virus (VZV)

Workup

Laboratory Studies Investigative studies Urinary proton nuclear magnetic resonance (1H NMR) spectroscopy–based metabolomic profiling appears to have the potential for identifying diagnostic biomarkers in the investigation of unstable angin pectoris metabolic signatures. [16] Investigators have demonstrated enhanced expression of toll-like receptors 2 and 4 (TLR-2 and TLR-4) on platelets in patients with acute coronary syndrome, which has potential clinical implications for prophylactic and therapeutic targets. [17]

Chest Radiography Chest radiograph findings are usually normal in patients with angina pectoris. However, they may show cardiomegaly in patients with previous MI, ischemic cardiomyopathy, pericardial effusion, or acute pulmonary edema. Calcification of coronary arteries frequently correlates with major coronary artery disease. [18]

Exercise Stress Testing Graded exercise stress testing is the most widely used test for the evaluation of patients presenting with chest pain. In patients with established stable angina pectoris, it also can provide prognostic information about the extent of disease. Exercise stress testing can be performed alone and in conjunction with echocardiography or myocardial perfusion scintigraphy tests. Stress echocardiography has an overall sensitivity of 78% and specificity of 86%; myocardial perfusion scintigraphy has an overall sensitivity of 83% and specificity of 77%. Exercise stress testing alone generally has somewhat lower sensitivity and specificity, but it is cheaper and therefore is a reasonable choice in those with a low probability of disease. [19] These test results must be interpreted in the context of the likelihood of the presence of coronary artery disease determined from the patient's history and physical examination findings. In a population with low prevalence, the predictive abilities of these tests are low; however, in patients with a high likelihood of coronary artery disease, the predictive value is much higher. The frequency of infarction or death is 1 case per 10,000 stress tests. Absolute contraindications include symptomatic cardiac arrhythmias, severe aortic stenosis, acute MI within the previous 2 days, acute myocarditis, or pericarditis. Discontinue the exercise stress test in the presence of chest pain, a drop in systolic blood pressure of more than 10 mm Hg, severe shortness of breath, fatigue, dizziness or near syncope, ST depression of more than 2 mm, ST elevation of at least 1 mm without diagnostic Q waves, or development of ventricular tachyarrhythmia.

Stress Echocardiography Stress echocardiography can be used to evaluate segmental wall motion during exercise. It detects changes in regional wall motion that occur during myocardial ischemia. Normal myocardium becomes hyperdynamic during exercise; ischemic segments become hypokinetic or akinetic. Stress echocardiography has the advantage of simultaneous evaluation of LV function, cardiac dimensions, and valvular disease. It is especially useful in patients with baseline ECG abnormalities and those with systolic murmurs suggestive of aortic stenosis or hypertrophic cardiomyopathy. It is also helpful for localizing ischemia and evaluating its severity. Signs of severe coronary artery disease during exercise stress echocardiography include LV dilation, a decrease in global systolic function, and new or worsening mitral regurgitation. However, with dobutamine stress echocardiography, even in patients with severe coronary artery disease, the LV cavity may not dilate and global systolic function may improve. A major problem with stress echocardiography is the technical difficulty with obtaining adequate images in some patients.

Nuclear Imaging Myocardial perfusion scintigraphy Thallium Tl 201 and technetium Tc 99m sestamibi are the most frequently used myocardial perfusion scintigraphy tests. These tests are especially useful in patients with baseline ECG abnormalities, to localize the region of ischemia, and as prognostic indicators. The presence of increased lung uptake upon thallium imaging is associated with a poor prognosis. Increased lung uptake, together with poststress dilation of the LV and multiple perfusion defects, is suggestive of either left main coronary artery disease or severe 3-vessel disease. The number of affected myocardial segments is predictive of long-term survival. Smaller perfusion defects are usually associated with peripheral coronary artery lesions, which are associated with a better prognosis. The absence of perfusion defects even in the presence of symptoms indicates an excellent prognosis.

Computed Tomography Scanning In relatively recent years, coronary artery calcium (CAC) scoring by fast computed tomography (CT) has become more popular in clinical practice for risk assessment of patients with chest pain. Currently, electron-beam computed tomography (EBCT) and multi-detector computed tomography (MDCT) are the primary fast CT methods for CAC measurement. However, some controversy exists about the usefulness of this test. [20] In asymptomatic patients, analysis of the data from CAC scoring in patients with an intermediate Framingham risk score reveals that for a score of 400 or more, the patient’s 10-year CAD risk would achieve a risk equivalent status similar to that noted with diabetes or peripheral arterial disease. [21] Thus, finding a high CAC score in asymptomatic patients with an intermediate Framingham risk score (10-20% risk of CAD in 10 y) could be useful by resulting in a more aggressive management approach. However, unselected screening is of limited clinical value in asymptomatic patients who have a low Framingham risk score. On the other hand, assessment of CAC in asymptomatic patients with a high Framingham risk score (>20% risk of CAD in 10 y) has limited value since, based on current guidelines, these patients should be treated aggressively irrespective of their CAC scoring. In symptomatic patients, exclusion of measurable CAC may be an effective tool before undertaking invasive diagnostic procedures or hospital admission. Patients with CAC scores of less than 100 have a low probability (< 2%) of abnormal perfusion on nuclear stress tests, and a low probability (< 3%) of obstructive CAD (>50% stenosis) on cardiac catheterization. Studies of large numbers of symptomatic patients demonstrated that the absence of CAC has a high negative predictive value of 96-100%. Thus, an individual with no coronary calcium (score _ 0) can be told with a high level of confidence that he or she has no obstructive angiographic coronary disease. In patients with documented CAD, clinical monitoring of CAC progression through serial fast CT scanning to assess progression or regression of CAD is not recommended at this time. Because most of current data regarding CAC are collected from patient population of mostly white men, the guidelines suggest caution in applying these findings to women and ethnic minorities.

CT Angiography In a 2008 study of 79 patients with stable angina pectoris, all patients underwent both dual-source computed tomography coronary angiography (CTCA) with quantitative CT coronary angiography (QCT) and coronary angiography with intracoronary fractional flow reserve (FFR) measurement of discrete coronary stenoses. [22] A total of 89 stenoses were evaluated which demonstrated that correlation between QCT and QCA with FFR measurement was weak (R values of -0.32 and -0.30, respectively). Although correlation between QCT and QCA was statistically significant, this correlation was only moderate (R = 0.53; p < 0.0001). This study demonstrated that anatomical assessment of the hemodynamic significance of coronary stenoses determined by visual CTCA, CCA, or QCT or QCA does not correlate well with the functional assessment of FFR. Bamberg et al found that, in patients with acute chest pain and an inconclusive initial evaluation (nondiagnostic electrocardiographic findings, negative cardiac biomarkers), age and gender can serve as simple criteria to select patients who would derive the greatest diagnostic benefit from coronary computed tomographic angiography (CTA). In an observational cohort study in 368 low-risk patients, positive findings on 64-slice coronary CTA led to restratification to high risk, and negative findings led to restratification to very low risk, in men younger than 55 years and women younger than 65 years. In contrast, in women older than 65 years and men older than 55 years, a negative result on CTA did not result in restratification to a low-risk category. [23]

Electrocardiography ECG is useful for evaluating persons with angina pectoris; however, findings are variable among patients.

Approximately 50% of patients with angina pectoris have normal findings after a resting ECG. However, abnormalities such as evidence for prior MI, intraventricular conduction delay, various degrees of atrioventricular block, arrhythmias, or ST-T–wave changes may be seen. During an attack of angina pectoris, 50% of patients with normal findings after resting ECG show abnormalities. A 1-mm or greater depression of the ST segment below the baseline, measured 80 milliseconds from the J point, is the most characteristic change. Reversible ST-segment elevation occurs with Prinzmetal angina. Some patients with coronary artery disease may show pseudonormalization of the resting ECG ST-T–wave abnormalities during episodes of chest pain. Exercise with ECG monitoring Exercise with ECG monitoring alone is the initial procedure of choice in patients without baseline ST-segment abnormalities or in whom anatomic localization of ischemia is not a consideration. Note the following:

• Horizontal or down-sloping ST-segment depression of at least 1 mm, measured 80 milliseconds from the J point, is considered the characteristic ischemic response.

• ST-segment depression of more than 2 mm at a low workload or that persists for more than 5 minutes after termination of exercise and a failure of blood pressure to rise or an actual drop in blood pressure are signs of severe ischemic heart disease and a poor prognosis.

• Withhold beta-blockers for approximately 48 hours before the stress test, whenever possible. Patients on digoxin and those with LV hypertrophy with repolarization abnormalities more often show positive results. Exercise stress tests have lower sensitivity and specificity in women and in patients with left bundle-branch block.

• Pharmacologic agents (eg, dobutamine, dipyridamole, adenosine) can be used in patients who are unable to exercise.

Ambulatory ECG monitoring Ambulatory ECG monitoring can be used for diagnostic purposes in patients with chest pain suggestive of Prinzmetal angina but is primarily used to evaluate the frequency of silent ischemia. Silent ischemia has been shown to be an independent predictor of mortality in patients with angina pectoris.

Procedures Coronary angiography Selective coronary angiography is the definitive diagnostic test for evaluating the anatomic extent and severity of coronary artery disease. Consider coronary angiography in symptomatic patients with inconclusive noninvasive study results, in survivors of sudden cardiac death, in those who are considered to have a poor prognosis based on the results of noninvasive studies, in those with occupational requirements for a definite diagnosis (eg, pilots), or in patients with coronary artery disease who are severely symptomatic despite maximal medical therapy. In patients in whom Prinzmetal angina is suggested, provocative testing with ergonovine maleate during coronary angiography may be useful. Intra-aortic balloon counterpulsation Intra-aortic balloon counterpulsation can be used in patients who continue to have unstable angina pectoris despite maximal medical treatment. This procedure should be followed promptly by coronary angiography with possible coronary revascularization. [3] Enhanced external counterpulsation In patients whose angina is refractory to medical therapy who are not suitable candidates for either percutaneous or surgical revascularization, enhanced external counterpulsation (EECP) is a safe and noninvasive alternative therapy. [4, 24] It increases coronary perfusion and reduces myocardial oxygen demand by diastolic augmentation of the central aortic pressure. Several studies have shown that patients treated with enhanced external counterpulsation have a significantly reduced number of anginal episodes, improved exercise tolerance, and decreased daily use of nitroglycerin tablets. Its therapeutic effects on quality of life are noted to remain at 1-year follow-up. [25, 26] EECP also improves systolic blood pressure in patients with refractory angina. In a recent study of 108 consecutive patients undergoing EECP, on average, EECP decreased systolic blood pressure during treatment and follow-up; but in patients with low baseline systolic blood pressure (< 110 mm Hg), EECP significantly increased systolic blood pressure. [4]

Staging The Canadian Cardiovascular Society grading scale is used for classification of angina severity, as follows:

• Class I - Angina only during strenuous or prolonged physical activity

• Class II - Slight limitation, with angina only during vigorous physical activity

• Class III - Symptoms with everyday living activities, ie, moderate limitation

• Class IV - Inability to perform any activity without angina or angina at rest, ie, severe limitation

The New York Heart Association classification is also used to quantify the functional limitation imposed by patients' symptoms, as follows:

• Class I - No limitation of physical activity (Ordinary physical activity does not cause symptoms.)

• Class II - Slight limitation of physical activity (Ordinary physical activity does cause symptoms.)

• Class III - Moderate limitation of activity (Patient is comfortable at rest, but less than ordinary activities cause symptoms.)

• Class IV - Unable to perform any physical activity without discomfort, therefore severe limitation (Patient may be symptomatic even at rest.)

Unstable angina is defined as new-onset angina (ie, within 2 mo of initial presentation) of at least class III severity, significant recent increase in frequency and severity of angina, or angina at rest.

Treatment & Management

Medical Care The main goals of treatment in angina pectoris are to relieve the symptoms, slow the progression of disease, and reduce the possibility of future events, especially MI and premature death. General measures Smoking cessation results in a significant reduction of acute adverse effects on the heart and may reverse, or at least slow, atherosclerosis. Strongly encourage patients to quit smoking, and take an active role in helping them to achieve this goal. Treat risk factors, including hypertension, diabetes mellitus, obesity, and hyperlipidemia. Several clinical trials have shown that in patients with established coronary artery disease, reduction of low-density lipoprotein (LDL) level with a beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor (ie, statin) is associated with significant reductions in both mortality rate and major cardiac events. [27, 28, 29, 30] These benefits are present even in patients with mild-to-moderate elevations of LDL cholesterol level. Trials with cholesterol-lowering agents have confirmed the benefits of the therapeutic LDL lowering in older persons. Angiographic studies demonstrate that a reduction of the LDL level in patients with coronary artery disease could cause slowing of progression, stabilization, or even regression of coronary artery lesions. One study demonstrated a significant reduction of symptomatic myocardial ischemia in patients with unstable angina or non–Q-wave infarction with the administration of a statin during the early acute phase. In a study of 10,001 patients with stable coronary artery disease, an aggressive cholesterol-lowering approach with atorvastatin 80 mg daily (mean cholesterol level of 77 mg/dL) compared to a less-aggressive approach with atorvastatin 10 mg daily (mean cholesterol level of 101 mg/dL) resulted in a 2.2% absolute reduction and a 22% relative reduction in the occurrence of a first major cardiovascular event (defined as death from coronary heart disease; nonfatal, non–procedure-related myocardial infarction; resuscitation from cardiac arrest; or fatal or nonfatal stroke). [31] This occurred with a greater incidence of elevated aminotransferase levels with the aggressive cholesterol-lowering approach (1.2% vs 0.2%, p < 0.001). Some triglyceride-rich lipoproteins, including partially degraded very LDL levels, are believed to be independent risk factors for coronary artery disease. In daily practice, non-HDL cholesterol level (ie, LDL + very LDL cholesterol [total cholesterol - HDL cholesterol]) is the most readily available measure of the total pool of these atherogenic lipoproteins. Thus, the ATP III has identified non-HDL cholesterol level as a secondary target of therapy in persons with high triglyceride levels (>200 mg/dL). The goal for non-HDL cholesterol level (for persons with serum triglyceride levels >200 mg/dL) is 30 mg/dL higher than the identified LDL cholesterol level goal. Patients with established coronary disease and low HDL cholesterol levels are at high risk for recurrent events and should be targeted for aggressive nonpharmacological (ie, dietary modification, weight loss, physical exercise) and pharmacological treatment. Several large epidemiologic studies demonstrated that HDL cholesterol levels are inversely related to cardiovascular risk. Thus, developing pharmaceutical agents to increase the HDL level has been an attractive target for prevention and treatment of CAD. However, several large randomized trials utilizing cholesteryl ester transfer protein (CETP) inhibitors did not show benefit for reducing cardiovascular events in spite of raising HDL levels. Torcetrapib has been one of CETP agents that has been used in large randomized trials. [32, 33] Investigation of Lipid level management using coronary UltraSound To assess Reduction of Atherosclerosis by CETP inhibition and HDL Elevation (ILLUSTRATE) was a randomized study that looked at the effect of torcetrapib in 1188 patients with CAD who underwent intravascular ultrasonography at baseline. [32] After treatment with atorvastatin to reduce levels of LDL cholesterol to less than 100 mg/dL, patients were randomly assigned to receive atorvastatin monotherapy or atorvastatin plus 60 mg of torcetrapib daily. Intravascular ultrasonography was repeated in 910 of these patients (77%) after 24 months of treatment to evaluate the disease progression. Compared with atorvastatin monotherapy, torcetrapib–atorvastatin therapy was associated with an impressive 61% relative increase in HDL levels and a 20% relative decrease in LDL levels resulting in an LDL to HDL ratio of less than 1.0 in this group of patients. Despite this favorable change in the HDL and LDL levels, among patients who underwent repeat intravascular ultrasonography, the percent atheroma volume between the 2 groups was not different. Torcetrapib did not result in significant decrease in the progression of coronary atherosclerosis, but it was associated with an increase in blood pressure. Rating Atherosclerotic Disease change by Imaging with A New Cholesteryl-Ester-transfer protein inhibitor (RADIANCE) 2, a trial reported in 2007, looked into the effect of torcetrapib on carotid atherosclerosis progression in patients with mixed dyslipidaemia. [33] Although similar to the ILLUSTRATE trial, torcetrapib also substantially raised HDL levels and lowered LDL levels in this study; it did not affect the progression of carotid atherosclerosis. Similar to the ILLUSTRATE trial, torcetrapib also significantly increased systolic blood pressure. Investigation of Lipid level management to Understand its iMpact IN ATherosclerotic Events (ILLUMINATE), an international phase 3 study of 15,000 patients, was terminated early because it had already recorded 82 deaths in the patients taking torcetrapib-atorvastatin compared with 51 deaths in patients taking atorvastatin alone. In addition, the rates of MI, revascularization, angina, and heart failure were higher in the torcetrapib-atorvastatin arm. Due to the similar failure of multiple clinical trials focused on HDL raising, current expert thinking about HDL is that it is to be regarded as a marker of risk rather than as a target of therapy. Other approaches to cardiac risk factor reduction should also be used in combination with the above. Exercise training results in improvement of symptoms, an increase in the threshold of ischemia, and improvement of patients' sense of well-being. However, before enrolling a patient in an exercise-training program, perform an exercise tolerance test to establish the safety of such a program. Enteric-coated aspirin at a dose of 81 mg per day should be advised for all patients with stable angina who have no contraindications to its use. [34, 35] In patients in whom aspirin cannot be used because of allergy or gastrointestinal complications, consider clopidogrel. [36] Although early observational studies suggested a cardiovascular protective effect with the use of hormone replacement therapy, recent large randomized trials failed to demonstrate any benefit with hormone replacement therapy in the primary or secondary prevention of cardiovascular disease. [37] In fact, these studies even demonstrated an increased risk of coronary artery disease and stroke in patients on hormone replacement therapy. The Women's Health Initiative study demonstrated that the use of hormone replacement therapy for 1 year in 10,000 healthy postmenopausal women is associated with 7 more instances of coronary artery disease, 8 more strokes, 8 more pulmonary emboli, 8 more invasive breast cancers, 5 fewer hip fractures, and 6 fewer colorectal cancers. Based on these data, the risks and benefits of hormone replacement therapy must be assessed on an individual basis for each patient. Sublingual nitroglycerin has been the mainstay of treatment for angina pectoris. Sublingual nitroglycerin can be used for acute relief of angina and prophylactically before activities that may precipitate angina. No evidence indicates that long-acting nitrates improve survival in patients with coronary artery disease. [38] Beta-blockers are also used for symptomatic relief of angina and prevention of ischemic events. They work by reducing myocardial oxygen demand and by decreasing the heart rate and myocardial contractility. Beta-blockers have been shown to reduce the rates of mortality and morbidity following acute MI. [39] A post hoc analysis from the ADDITIONS (prActical Daily efficacy anD safety of Procoralan In combinaTION with betablockerS) trial demonstrated metoprolol in combination with ivabradine for treatment of patients with stable angina was safe and effective. [40] The investigators reported a reduction in heart rate by 19.7 +/- 11.2 bpm, with an 8-fold decrease in weekly angina attacks and nitrate use, accompanied by improvement in quality of life. [40] Long-acting heart rate–slowing calcium channel blockers can be used to control anginal symptoms in patients with a contraindication to beta-blockers and in those in whom symptomatic relief of angina cannot be achieved with the use of beta-blockers, nitrates, or both. Avoid short-acting dihydropyridine calcium channel blockers because they have been shown to increase the risk of adverse cardiac events. Anginal symptoms in patients with Prinzmetal angina can be treated with calcium channel blockers with or without nitrates. In one study, supplemental vitamin E added to a calcium channel blocker significantly reduced anginal symptoms among such patients. [41] In patients with syndrome X and hypertension, ACE inhibitors may normalize thallium perfusion defects and increase exercise capacity. [42] A study by Losordo et al proposes injections of autologous CD34+ cells (105 cells/kg) for patients with refractory angina. Patients who received this experienced significant improvements in angina frequency and exercise tolerance. [2] Diet and activity A diet low in saturated fat and dietary cholesterol is the mainstay of the Step I and Step II diet from the American Heart Association. The level of activity that aggravates anginal symptoms is different for each patient. However, most patients with stable angina can avoid symptoms during daily activities simply by reducing the speed of activity.

Surgical Care Revascularization therapy (ie, coronary revascularization) can be considered in patients with left main artery stenosis greater than 50%, 2- or 3-vessel disease and LV dysfunction (ejection fraction, < 45%), poor prognostic signs during noninvasive studies, or severe symptoms despite maximum medical therapy. The 2 main coronary revascularization procedures are percutaneous transluminal coronary angioplasty, with or without coronary stenting, and coronary artery bypass grafting (CABG). Patients with 1- or 2-vessel disease and normal LV function who have anatomically suitable lesions are candidates for percutaneous transluminal coronary angioplasty and coronary stenting. Restenosis is the major complication, with symptomatic restenosis occurring in 20-25% of patients. Restenosis mostly occurs during the first 6 months after the procedure and can be managed by repeat angioplasty. Several trials have demonstrated that the use of drug-eluting stents (eg, sirolimus-eluting stents, paclitaxel-coated stents) can remarkably reduce the rate of in-stent restenosis. With the introduction of these drug-coated stents, patients with multivessel coronary artery disease are more frequently treated with percutaneous revascularization as opposed to the surgical revascularization. [43, 44] More recently, some concerns have arisen that instead of improving the long-term prognosis, drug-eluting stents might actually worsen it. In addition, stent thrombosis is a major concern with the useofdrug-eluting stents. A meta-analysis of individual data on 4,958 patients enrolled in 14 randomized trials comparing sirolimus-eluting stents with bare-metal stents looked at the long-term effect of these stents. [44] The mean follow-up interval was 12.1-58.9 months. The primary end point was death from any cause. The secondary end points were stent thrombosis, the composite end point of death or myocardial infarction, and the composite of death, MI, or a revascularization. The overall risk of death and the combined risk of death or MI were not significantly different for patients receiving sirolimus-eluting stents versus bare-metal stents. A sustained reduction in the need for revascularization occurred after the use of sirolimus-eluting stents compared with bare-metal stents. The overall risk of stent thrombosis with sirolimus-eluting stents was not significantly higher than bare-metal stents. However, evidence showed an increase in the risk of stent thrombosis associated with sirolimus-eluting stents after the first year. Patients with single-vessel disease and normal ventricular function treated with percutaneous transluminal coronary angioplasty show improved exercise tolerance and fewer episodes of angina compared with those who receive medical treatment. However, no difference in the frequency of MI or death has been shown between these two groups. The Clinical Outcomes Utilizing Revascularization and AGgressive Drug Evaluation (COURAGE) trial looked at the benefits of PCI as an initial management strategy in patients with stable CAD. This trial was a randomized and involved 2287 patients who had objective evidence of myocardial ischemia and significant CAD. [45] Of these, 1149 patients were randomized to undergo PCI with optimal medical therapy (PCI group) and 1138 were to receive optimal medical therapy alone (medical-therapy group). They were observed for 2.5-7 years (median, 4.6 y). During the follow-up, no difference was reported in the primary outcome of death from any cause and nonfatal MI between the PCI group and the medical-therapy group. In addition, no significant differences were noted between the 2 groups in the secondary end points of the composite of death, MI, and stroke; hospitalization for acute coronary syndrome; or MI. A 2012 study was prematurely halted after it showed a significant benefit in its primary endpoint (a composite of death, myocardial infarction, or urgent revascularization) in patients with stable coronary disease who underwent fractional flow reserve (FFR)-guided PCI plus the best available medical therapy (PCI group) compared to those who received only the best available medical therapy alone (medical-therapy group). In this study, patients in whom at least one stenosis was functionally significant (FFR, ≤0.80) were randomly assigned to FFR-guided PCI plus the best available medical therapy or the best available medical therapy alone while patients in whom all stenosis had an FFR > 0.80 received the best available medical therapy. The significant difference in primary endpoint was driven by a lower rate of urgent revascularization in the FFR-guided PCI patients (1.6%) than in the medical-therapy alone patients (11.1%; hazard ratio, 0.13; 95% CI, 0.06 to 0.30; P< 0.001). Significantly fewer urgent revascularizations were triggered by a myocardial infarction or evidence of ischemia on electrocardiography in the FFR-guided PCI group. The authors conclude that in patients with stable coronary artery disease and functionally significant stenosis, FFR-guided PCI plus the best available medical therapy reduces the need for urgent revascularization compared with the best available medical therapy alone. In patients without ischemia, the outcome is favorable with the best available medical therapy alone. These results suggest a significant role for use of FFR in patients with stable coronary artery disease to select those who might benefit from PCI. [46] Patients with significant left main coronary artery disease, 2- or 3-vessel disease and LV dysfunction, diabetes mellitus, or lesions anatomically unsuitable for percutaneous transluminal coronary angioplasty have better results with coronary artery bypass grafting. The overall operative mortality rate for coronary artery bypass grafting is approximately 1.3%. The rate of graft patency 10 years after surgery is less than 50% for vein grafting, although more than 90% of grafts using internal mammary arteries are patent at 10 years. In recent years, interest has increased regarding surgery without cardiopulmonary bypass (ie, off-pump) in an attempt to avoid the morbidity associated with cardiopulmonary bypass. A recent randomized study demonstrated that off-pump coronary surgery was as safe as on-pump surgery and caused less myocardial damage. However, the graft-patency rate was lower at 3 months in the off-pump group than in the on-pump group. Laser transmyocardial revascularization Laser transmyocardial revascularization has been used as an experimental therapy for the treatment of severe, chronic, stable angina refractory to medical or other therapies. [5] This technique has been performed with either an epicardial surgical technique or by a percutaneous approach. In both approaches, a series of transmural endomyocardial channels are created to improve myocardial perfusion. The surgical transmyocardial revascularization technique has been associated with symptomatic relief for end-stage chronic angina in the short term. However, no published data address the long-term efficacy of surgical transmyocardial revascularization. Nonetheless, this technique appears to provide at least symptomatic relief for end-stage chronic angina in the short term. [47] Human CD34+ stem cells A subgroup of patients with coronary artery disease experiences angina that is not amenable to revascularization and is refractory to medical therapy. Some studies have indicated that human CD34+ stem cells induce neovascularization in ischemic myocardium enhancing perfusion and function. The feasibility and safety of this treatment was tested in a recent phase I/IIa double-blind, randomized controlled trial of 24 patients (19 men and 5 women aged 48-84 y) with Canadian Cardiovascular Society class 3 or 4 angina who were undergoing optimal medical treatment and who were not candidates for mechanical revascularization. [48] Patients received granulocyte colony-stimulating factor 5 microg x kg(-1) x d(-1) for 5 days with leukapheresis on the fifth day. Electromechanical mapping was performed to identify ischemic but viable regions of myocardium for injection of cells in the active treatment group versus saline injection in the placebo group. The total dose of cells was divided in 10 intramyocardial and transendocardial injections. There was no incidence of myocardial infarction, elevation of cardiac enzymes, perforation, or pericardial effusion. Also, there was no incidence of ventricular tachycardia or ventricular fibrillation during the administration of granulocyte colony-stimulating factor or intramyocardial injections. Serious adverse events were evenly distributed between the therapy and the control groups. A trend was demonstrated in frequency of angina, nitroglycerine usage, exercise time, and Canadian Cardiovascular Society class that favored CD34+ cell-treated patients versus control subjects given saline injections. Based on the results of this study a larger phase IIb study is currently under way to further evaluate this novel therapy. Increased coronary sinus pressure Increased coronary sinus pressure has been suggested to reduce myocardial ischemia by redistribution of blood from nonischemic to ischemic areas. The Coronary Sinus Reducer is a percutaneous implantable device designed to establish coronary sinus narrowing and to elevate coronary sinus pressure. In a 2007 study, the safety and feasibility of the Coronary Sinus Reducer was evaluated in 15 patients with coronary artery disease and refractory angina who were not candidates for revascularization. [49] All procedures were completed successfully and no procedure-related adverse events occurred during the periprocedural and the follow-up periods. Angina score improved in 12 of 14 patients. Also, the extent and severity of myocardial ischemia measured by dobutamine echocardiography and by thallium single-photon emission computed tomography was reduced significantly (p = 0.004 [n = 13] and p = 0.042 [n = 10], respectively). This study demonstrated that the implantable Coronary Sinus Reducers may be a feasible and safe treatment for patients with refractory angina. Further large clinical studies are needed before the use of these devices become an accepted treatment.

Prevention Coronary atherosclerosis is the main preventable cause of mortality in the United States. A rigorous effort to address correctable risk factors is the mainstay of preventive cardiovascular medicine. Smoking cessation is the single most effective preventive intervention to reduce coronary atherosclerosis prevalence. It has been associated with a coronary artery disease reduction of 7-47% in primary prevention settings. Aggressive treatment of diabetes mellitus, hypertension, LV hypertrophy, hyperlipidemia, and obesity has an important role in the prevention of coronary artery disease. The most important recent development in coronary atherosclerosis risk modification is the introduction of inhibitors of beta-hydroxy-beta-methylglutaryl coenzyme A reductase. Reductions of total and LDL cholesterol levels by 25% and 35%, respectively, can achieve a similar reduction in rates of total and coronary mortality, MI, and need for coronary revascularization.

Medication

Medication Summary The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Antiplatelet agents Class Summary Prevent thrombus formation by inhibiting platelet aggregation. Aspirin is proven beneficial in primary and secondary prevention of coronary artery disease. In patients with aspirin intolerance, use clopidogrel. Clopidogrel is also used in combination with aspirin after coronary stent placement. Recently, clopidogrel use in addition to aspirin has been shown to be significantly superior to aspirin alone in patients with acute coronary syndrome without ST-segment elevation MI. Aspirin (Anacin, Ascriptin, Bayer Aspirin, Bayer Buffered Aspirin)

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Prevents platelet aggregation by irreversible cyclooxygenase inhibition with subsequent suppression of thromboxane A2. Antiplatelet effect can last as long as 7 d. Clopidogrel (Plavix)

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Selectively inhibits ADP binding to platelet receptor and subsequent ADP-mediated activation of GPIIb/IIIa complex, thereby inhibiting platelet aggregation. Consider in patients with contraindication to aspirin.

Beta-adrenergic blocking agents Class Summary Work by competing with endogenous catecholamines for beta-adrenergic receptors. Reduce myocardial oxygen consumption via several effects, including decrease in resting and exercise heart rates and reductions in myocardial contractility and afterload. Classified as nonselective, beta-1 selective, and having intrinsic sympathomimetic effects. Metoprolol (Lopressor, Toprol XL)

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Selective beta1-adrenergic receptor blocker that decreases automaticity of contractions. Is lipophilic and penetrates CNS. Atenolol (Tenormin)

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Selectively blocks beta-1 receptors with little or no effect on beta-2 receptors. Is hydrophilic and does not penetrate CNS. Propranolol (Inderal)

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Nonselective beta-blocker that is lipophilic (penetrates CNS). Although generally short-acting agent, long-acting preparations also available.

Calcium channel blockers Class Summary Reduce transmembrane flux of calcium via calcium channels. Cause smooth muscle relaxation, resulting in peripheral arterial vasodilation and afterload reduction. Indicated when symptoms persist despite treatment with beta-blockers or when beta-blockers are contraindicated. Also indicated in patients with Prinzmetal angina with or without nitrates. Amlodipine (Norvasc)

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During depolarization, inhibits calcium ions from entering slow channels and voltage-sensitive areas of vascular smooth muscle and myocardium. Diltiazem (Cardizem CD, Dilacor)

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During depolarization, inhibits calcium ions from entering slow channels and voltage-sensitive areas of vascular smooth muscle and myocardium. Verapamil (Calan, Covera)

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During depolarization, inhibits calcium ion from entering slow channels or voltage-sensitive areas of vascular smooth muscle and myocardium.

Short-acting nitroglycerins Class Summary Suitable for immediate relief of exertional or rest angina. Can also be used for prophylaxis several minutes before planned exercise to avoid angina. Reduce myocardial oxygen demand by reduction of LV and arterial pressure, primarily by reducing preload. Nitroglycerin IV (Nitrostat, Nitro-bid, Nitrol)

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Causes relaxation of vascular smooth muscle by stimulating intracellular cyclic GMP production. Result is decrease in BP.

Long-acting nitroglycerins Class Summary Reduce LV preload and afterload by venous and arterial dilation, which subsequently reduces myocardial oxygen consumption and relieves angina. Also cause dilation of epicardial coronary arteries, which is beneficial in patients with coronary spasm. In addition, nitroglycerin has antithrombotic and antiplatelet effects in patients with angina pectoris. No evidence suggests that nitrates improve survival or slow progression of coronary artery disease. Isosorbide (Isordil, ISMO)

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Relaxes vascular smooth muscle by stimulating intracellular cyclic GMP. Decreases LV pressure (ie, preload) and arterial resistance (ie, afterload). Reduces cardiac oxygen demand by decreasing LV pressure and dilating arteries.

Angiotensin-converting enzyme inhibitors Class Summary Angiotensin-converting enzyme (ACE) Inhibitors have been shown to reduce rates of death, MI, stroke, and need for revascularization procedures in patients with coronary artery disease or diabetes mellitus and at least one other cardiovascular risk factor, [61] irrespective of the presence of hypertension or heart failure. The 2009 Canadian Hypertension Education Program recommends beta-blockers and ACE inhibitors as first-line therapy in patients with angina, recent myocardial infarction or heart failure. [62] Ramipril (Altace)

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Prevents conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, resulting in lower aldosterone secretion.

Anti-ischemic agents, miscellaneous Class Summary Ranolazine elicits action unlike beta-blockers, calcium antagonists, or nitrates. It does not affect hemodynamics or contractile and conduction parameters. Ranolazine (Ranexa)

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Cardioselective anti-ischemic agent (piperazine derivative) that partially inhibits fatty acid oxidation. Also inhibits late sodium current into myocardial cells and prolongs QTc interval. Indicated for chronic angina unresponsive to other antianginal treatments. Used in combination with amlodipine, beta-blockers, or nitrates. Unlike beta-blockers, calcium channel blockers, and nitrates, does not reduce blood pressure or heart rate. Effect on angina rate or exercise tolerance appears to be smaller in women than in men. Absorption is highly variable but unaffected by food.

References

1. [Guideline] National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation. 2002 Dec 17. 106(25):3143-421. [QxMD MEDLINE Link]. [Full Text].

2. Losordo DW, Henry TD, Davidson C, et al. Intramyocardial, autologous CD34+ cell therapy for refractory angina. Circ Res. 2011 Aug 5. 109(4):428-36. [QxMD MEDLINE Link].

3. den Uil CA, Valk SD, Cheng JM, et al. Prognosis of patients undergoing cardiac surgery and treated with intra-aortic balloon pump counterpulsation prior to surgery: a long-term follow-up study. Interact Cardiovasc Thorac Surg. 2009 Aug. 9(2):227-31. [QxMD MEDLINE Link].

4. Campbell AR, Satran D, Zenovich AG, et al. Enhanced external counterpulsation improves systolic blood pressure in patients with refractory angina. Am Heart J. 2008 Dec. 156(6):1217-22. [QxMD MEDLINE Link].

5. Oesterle SN, Sanborn TA, Ali N, et al. Percutaneous transmyocardial laser revascularisation for severe angina: the PACIFIC randomised trial. Potential Class Improvement From Intramyocardial Channels. Lancet. 2000 Nov 18. 356(9243):1705-10. [QxMD MEDLINE Link].

6. Crea F, Pupita G, Galassi AR, et al. Role of adenosine in pathogenesis of anginal pain. Circulation. 1990 Jan. 81(1):164-72. [QxMD MEDLINE Link].

7. Kugiyama K, Yasue H, Okumura K, et al. Nitric oxide activity is deficient in spasm arteries of patients with coronary spastic angina. Circulation. 1996 Aug 1. 94(3):266-71. [QxMD MEDLINE Link].

8. Rosano GM, Collins P, Kaski JC, et al. Syndrome X in women is associated with oestrogen deficiency. Eur Heart J. 1995 May. 16(5):610-4. [QxMD MEDLINE Link].

9. Kaski JC, Elliott PM, Salomone O, et al. Concentration of circulating plasma endothelin in patients with angina and normal coronary angiograms. Br Heart J. 1995 Dec. 74(6):620-4. [QxMD MEDLINE Link].

10. Lanza GA, Giordano A, Pristipino C, et al. Abnormal cardiac adrenergic nerve function in patients with syndrome X detected by [123I]metaiodobenzylguanidine myocardial scintigraphy. Circulation. 1997 Aug 5. 96(3):821-6. [QxMD MEDLINE Link].

11. Deedwania PC, Carbajal EV. Silent ischemia during daily life is an independent predictor of mortality in stable angina. Circulation. 1990 Mar. 81(3):748-56. [QxMD MEDLINE Link].

12. Kuo L, Davis MJ, Chilian WM. Longitudinal gradients for endothelium-dependent and -independent vascular responses in the coronary microcirculation. Circulation. 1995 Aug 1. 92(3):518-25. [QxMD MEDLINE Link].

13. Lloyd-Jones D, Adams R, Carnethon M, et al. Heart disease and stroke statistics--2009 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation. 2009 Jan 27. 119(3):e21-181. [QxMD MEDLINE Link].

14. Hemingway H, Langenberg C, Damant J, Frost C, Pyorala K, Barrett-Connor E. Prevalence of angina in women versus men: a systematic review and meta-analysis of international variations across 31 countries. Circulation. 2008 Mar 25. 117(12):1526-36. [QxMD MEDLINE Link].

15. Tanindi A, Erkan AF, Ekici B. Epicardial adipose tissue thickness can be used to predict major adverse cardiac events. Coron Artery Dis. 2015 Dec. 26 (8):686-91. [QxMD MEDLINE Link].

16. Li Z, Liu X, Wang J, et al. Analysis of urinary metabolomic profiling for unstable angina pectoris disease based on nuclear magnetic resonance spectroscopy. Mol Biosyst. 2015 Dec 10. 11(12):3387-96. [QxMD MEDLINE Link].

17. Gurses KM, Kocyigit D, Yalcin MU, et al. Enhanced platelet toll-like receptor 2 and 4 expression in acute coronary syndrome and stable angina pectoris. Am J Cardiol. 2015 Dec 1. 116(11):1666-71. [QxMD MEDLINE Link].

18. Grundy SM, Cleeman JI, Merz CN, et al. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III Guidelines. J Am Coll Cardiol. 2004 Aug 4. 44(3):720-32. [QxMD MEDLINE Link].

19. O'Keefe JH Jr, Barnhart CS, Bateman TM. Comparison of stress echocardiography and stress myocardial perfusion scintigraphy for diagnosing coronary artery disease and assessing its severity. Am J Cardiol. 1995 Apr 13. 75(11):25D-34D. [QxMD MEDLINE Link].

20. [Guideline] Greenland P, Bonow RO, Brundage BH, et al. ACCF/AHA 2007 clinical expert consensus document on coronary artery calcium scoring by computed tomography in global cardiovascular risk assessment and in evaluation of patients with chest pain: a report of the American College of Cardiology Foundation Clinical Expert Consensus Task Force (ACCF/AHA Writing Committee to Update the 2000 Expert Consensus Document on Electron Beam Computed Tomography) developed in collaboration with the Society of Atherosclerosis Imaging and Prevention and the So... J Am Coll Cardiol. 2007 Jan 23. 49(3):378-402. [QxMD MEDLINE Link]. [Full Text].

21. Kannel WB, Feinleib M. Natural history of angina pectoris in the Framingham study. Prognosis and survival. Am J Cardiol. 1972 Feb. 29(2):154-63. [QxMD MEDLINE Link].

22. Meijboom WB, Van Mieghem CA, van Pelt N, et al. Comprehensive assessment of coronary artery stenoses: computed tomography coronary angiography versus conventional coronary angiography and correlation with fractional flow reserve in patients with stable angina. J Am Coll Cardiol. 2008 Aug 19. 52(8):636-43. [QxMD MEDLINE Link].

23. Bamberg F, Truong QA, Blankstein R, et al. Usefulness of age and gender in the early triage of patients with acute chest pain having cardiac computed tomographic angiography. Am J Cardiol. 2009 Nov 1. 104(9):1165-70. [QxMD MEDLINE Link]. [Full Text].

24. Soran O. Alternative therapy for medically refractory angina: enhanced external counterpulsation and transmyocardial laser revascularization. Heart Fail Clin. 2016 Jan. 12(1):107-16. [QxMD MEDLINE Link].

25. Arora RR, Chou TM, Jain D, et al. The multicenter study of enhanced external counterpulsation (MUST-EECP): effect of EECP on exercise-induced myocardial ischemia and anginal episodes. J Am Coll Cardiol. 1999 Jun. 33(7):1833-40. [QxMD MEDLINE Link].

26. Kumar A, Aronow WS, Vadnerkar A, et al. Effect of enhanced external counterpulsation on clinical symptoms, quality of life, 6-minute walking distance, and echocardiographic measurements of left ventricular systolic and diastolic function after 35 days of treatment and at 1-year follow up in 47 patients with chronic refractory angina pectoris. Am J Ther. 2009 Mar-Apr. 16(2):116-8. [QxMD MEDLINE Link].

27. Scandinavian Simvastatin Survival Study Group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S). Lancet. 1994 Nov 19. 344(8934):1383-9. [QxMD MEDLINE Link].

28. Schwartz GG, Olsson AG, Ezekowitz MD, et al. Effects of atorvastatin on early recurrent ischemic events in acute coronary syndromes: the MIRACL study: a randomized controlled trial. JAMA. 2001 Apr 4. 285(13):1711-8. [QxMD MEDLINE Link].

29. Sever PS, Dahlof B, Poulter NR, et al. Prevention of coronary and stroke events with atorvastatin in hypertensive patients who have average or lower-than-average cholesterol concentrations, in the Anglo-Scandinavian Cardiac Outcomes Trial--Lipid Lowering Arm (ASCOT-LLA): a multicentre randomi. Lancet. 2003 Apr 5. 361(9364):1149-58. [QxMD MEDLINE Link].

30. Shepherd J, Blauw GJ, Murphy MB, et al. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet. 2002 Nov 23. 360(9346):1623-30. [QxMD MEDLINE Link].

31. LaRosa JC, Grundy SM, Waters DD, et al. Intensive lipid lowering with atorvastatin in patients with stable coronary disease. N Engl J Med. 2005 Apr 7. 352(14):1425-35. [QxMD MEDLINE Link].

32. Nissen SE, Tardif JC, Nicholls SJ, et al. Effect of torcetrapib on the progression of coronary atherosclerosis. N Engl J Med. 2007 Mar 29. 356(13):1304-16. [QxMD MEDLINE Link].

33. Bots ML, Visseren FL, Evans GW, et al. Torcetrapib and carotid intima-media thickness in mixed dyslipidaemia (RADIANCE 2 study): a randomised, double-blind trial. Lancet. 2007 Jul 14. 370(9582):153-60. [QxMD MEDLINE Link].

34. Ridker PM, Manson JE, Gaziano JM, et al. Low-dose aspirin therapy for chronic stable angina. A randomized, placebo-controlled clinical trial. Ann Intern Med. 1991 May 15. 114(10):835-9. [QxMD MEDLINE Link].

35. Juul-Moller S, Edvardsson N, Jahnmatz B, et al. Double-blind trial of aspirin in primary prevention of myocardial infarction in patients with stable chronic angina pectoris. The Swedish Angina Pectoris Aspirin Trial (SAPAT) Group. Lancet. 1992 Dec 12. 340(8833):1421-5. [QxMD MEDLINE Link].

36. Yusuf S, Zhao F, Mehta SR, et al. Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation. N Engl J Med. 2001 Aug 16. 345(7):494-502. [QxMD MEDLINE Link].

37. Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results From the Women's Health Initiative randomized controlled trial. JAMA. 2002 Jul 17. 288(3):321-33. [QxMD MEDLINE Link].

38. Lacoste LL, Theroux P, Lidon RM, et al. Antithrombotic properties of transdermal nitroglycerin in stable angina pectoris. Am J Cardiol. 1994 Jun 1. 73(15):1058-62. [QxMD MEDLINE Link].

39. Norwegian Multicenter Study Group. Timolol-induced reduction in mortality and reinfarction in patients surviving acute myocardial infarction. N Engl J Med. 1981 Apr 2. 304(14):801-7. [QxMD MEDLINE Link].

40. Werdan K, Ebelt H, Nuding S, et al, for the ADDITIONS Study Investigators. Ivabradine in Combination with Metoprolol Improves Symptoms and Quality of Life in Patients with Stable Angina Pectoris: A post hoc Analysis from the ADDITIONS Trial. Cardiology. 2016. 133(2):83-90. [QxMD MEDLINE Link].

41. Miwa K, Miyagi Y, Igawa A, et al. Vitamin E deficiency in variant angina. Circulation. 1996 Jul 1. 94(1):14-8. [QxMD MEDLINE Link].

42. Kaski JC, Rosano G, Gavrielides S, Chen L. Effects of angiotensin-converting enzyme inhibition on exercise-induced angina and ST segment depression in patients with microvascular angina. J Am Coll Cardiol. 1994 Mar 1. 23(3):652-7. [QxMD MEDLINE Link].

43. Morice MC, Serruys PW, Sousa JE, et al. A randomized comparison of a sirolimus-eluting stent with a standard stent for coronary revascularization. N Engl J Med. 2002 Jun 6. 346(23):1773-80. [QxMD MEDLINE Link].

44. Kastrati A, Mehilli J, Pache J, et al. Analysis of 14 trials comparing sirolimus-eluting stents with bare-metal stents. N Engl J Med. 2007 Mar 8. 356(10):1030-9. [QxMD MEDLINE Link].

45. Boden WE, O'Rourke RA, Teo KK, et al. Optimal medical therapy with or without PCI for stable coronary disease. COURAGE Trial Research Group. N Engl J Med. 2007 Apr 12. 356(15):1503-16. [QxMD MEDLINE Link].

46. De Bruyne B, Pijls NH, Kalesan B, et al. Fractional flow reserve-guided PCI versus medical therapy in stable coronary disease. N Engl J Med. 2012 Sep 13. 367(11):991-1001. [QxMD MEDLINE Link].

47. Allen KB, Dowling RD, Fudge TL, et al. Comparison of transmyocardial revascularization with medical therapy in patients with refractory angina. N Engl J Med. 1999 Sep 30. 341(14):1029-36. [QxMD MEDLINE Link].

48. Losordo DW, Schatz RA, White CJ, et al. Intramyocardial transplantation of autologous CD34+ stem cells for intractable angina: a phase I/IIa double-blind, randomized controlled trial. Circulation. 2007 Jun 26. 115(25):3165-72. [QxMD MEDLINE Link].

49. Banai S, Ben Muvhar S, Parikh KH, et al. Coronary sinus reducer stent for the treatment of chronic refractory angina pectoris: a prospective, open-label, multicenter, safety feasibility first-in-man study. J Am Coll Cardiol. 2007 May 1. 49(17):1783-9. [QxMD MEDLINE Link].

50. [Guideline] Jellinger PS, Handelsman Y, Rosenblit PD, et al. American Association of Clinical Endocrinologists and American College of Endocrinology guidelines for management of dyslipidemia and prevention of cardiovascular disease. Endocr Pract. 2017 Apr. 23 (suppl 2):1-87. [QxMD MEDLINE Link].

51. [Guideline] Stone NJ, Robinson JG, Lichtenstein AH, et al, American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014 Jun 24. 129(25 Suppl 2):S1-45. [QxMD MEDLINE Link]. [Full Text].

52. [Guideline] Jellinger PS, Smith DA, Mehta AE, et al, for the AACE Task Force for Management of Dyslipidemia and Prevention of Atherosclerosis. American Association of Clinical Endocrinologists' Guidelines for Management of Dyslipidemia and Prevention of Atherosclerosis. Endocr Pract. 2012 Mar-Apr. 18(Suppl 1):1-78. [QxMD MEDLINE Link]. [Full Text].

53. [Guideline] Jacobson TA, Ito MK, Maki KC, et al. National Lipid Association recommendations for patient-centered management of dyslipidemia: part 1 - executive summary. J Clin Lipidol. 2014 Sep-Oct. 8(5):473-88. [QxMD MEDLINE Link]. [Full Text].

54. [Guideline] Fihn SD, Gardin JM, Abrams J,et al, American College of Cardiology Foundation/American Heart Association Task Force. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation. 2012 Dec 18. 126(25):e354-471. [QxMD MEDLINE Link]. [Full Text].

55. [Guideline] Fihn SD, Blankenship JC, Alexander KP, et al. 2014 ACC/AHA/AATS/PCNA/SCAI/STS focused update of the guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines, and the American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation. 2014 Nov 4. 130(19):1749-67. [QxMD MEDLINE Link]. [Full Text].

56. [Guideline] Montalescot G, Sechtem U, Achenbach S, et al, Task Force on the Management of Stable Coronary Artery Disease of the European Society of Cardiology. 2013 ESC guidelines on the management of stable coronary artery disease: the Task Force on the management of stable coronary artery disease of the European Society of Cardiology. Eur Heart J. 2013 Oct. 34(38):2949-3003. [QxMD MEDLINE Link]. [Full Text].

57. [Guideline] Windecker S, Kolh P, Alfonso F, et al, for the Task Force on Myocardial Revascularization of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS). Developed with the special contribution of the Europ. 2014 ESC/EACTS guidelines on myocardial revascularization. Eur Heart J. 2014 Oct 1. 35(37):2541-619. [QxMD MEDLINE Link]. [Full Text].

58. [Guideline] Levine GN, Bates ER, Bittl JA, et al. 2016 ACC/AHA guideline focused update on duration of dual antiplatelet therapy in patients with coronary artery disease: a report of the ACC/AHA Task Force on Clinical Practice Guidelines. Circulation. 2016 Sep 6. 134(10):e123-55. [QxMD MEDLINE Link]. [Full Text].

59. [Guideline] Valgimigli M, Bueno H, Byrne RA, et al, for the ESC Scientific Document Group, ESC Committee for Practice Guidelines (CPG), et al. 2017 ESC focused update on dual antiplatelet therapy in coronary artery disease developed in collaboration with EACTS: The Task Force for dual antiplatelet therapy in coronary artery disease of the European Society of Cardiology (ESC) and of the European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 2018 Jan 14. 39 (3):213-60. [QxMD MEDLINE Link].

60. [Guideline] Shore-Lesserson L, Baker RA, Ferraris VA, et al. The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines-Anticoagulation During Cardiopulmonary Bypass. Ann Thorac Surg. 2018 Feb. 105 (2):650-62. [QxMD MEDLINE Link].

61. Anderson HV. Angiotensin-converting enzyme inhibitors: ischemia is not the correct measure of benefit. J Am Coll Cardiol. 2003 Dec 17. 42(12):2060-2. [QxMD MEDLINE Link].

62. Khan NA, Hemmelgarn B, Herman RJ, et al. The 2009 Canadian Hypertension Education Program recommendations for the management of hypertension: Part 2--therapy. Can J Cardiol. 2009 May. 25(5):287-98. [QxMD MEDLINE Link]. [Full Text].

63. Ambrosio G, Betocchi S, Pace L, et al. Prolonged impairment of regional contractile function after resolution of exercise-induced angina. Evidence of myocardial stunning in patients with coronary artery disease. Circulation. 1996 Nov 15. 94(10):2455-64. [QxMD MEDLINE Link].

64. Boggs W. Coronary CT angiography, or usual care, in the ED? Medscape Medical News. February 6, 2013. Available at http://www.medscape.com/viewarticle/778873. Accessed: March 25, 2013.

65. Brown G, Albers JJ, Fisher LD, et al. Regression of coronary artery disease as a result of intensive lipid-lowering therapy in men with high levels of apolipoprotein B. N Engl J Med. 1990 Nov 8. 323(19):1289-98. [QxMD MEDLINE Link].

66. Califf RM, Armstrong PW, Carver JR, et al. 27th Bethesda Conference: matching the intensity of risk factor management with the hazard for coronary disease events. Task Force 5. Stratification of patients into high, medium and low risk subgroups for purposes of risk factor management. J Am Coll Cardiol. 1996 Apr. 27(5):1007-19. [QxMD MEDLINE Link].

67. Cannon CP, Braunwald E, McCabe CH, et al. Intensive versus moderate lipid lowering with statins after acute coronary syndromes. N Engl J Med. 2004 Apr 8. 350(15):1495-504. [QxMD MEDLINE Link].

68. Chauhan A, Mullins PA, Taylor G, et al. Both endothelium-dependent and endothelium-independent function is impaired in patients with angina pectoris and normal coronary angiograms. Eur Heart J. 1997 Jan. 18(1):60-8. [QxMD MEDLINE Link].

69. Connolly DC, Elveback LR, Oxman HA. Coronary heart disease in residents of Rochester, Minnesota. IV. Prognostic value of the resting electrocardiogram at the time of initial diagnosis of angina pectoris. Mayo Clin Proc. 1984 Apr. 59(4):247-50. [QxMD MEDLINE Link].

70. Frileux S, Munoz Sastre MT, Mullet E, Sorum PC. The impact of the preventive medical message on intention to change behavior. Patient Educ Couns. 2004 Jan. 52(1):79-88. [QxMD MEDLINE Link].

71. Hulten E, Pickett C, Bittencourt MS, et al. Outcomes after coronary computed tomography angiography in the emergency department: a systematic review and meta-analysis of randomized, controlled trials. J Am Coll Cardiol. 2013 Feb 26. 61(8):880-92. [QxMD MEDLINE Link].

72. Khan NE, De Souza A, Mister R, et al. A randomized comparison of off-pump and on-pump multivessel coronary-artery bypass surgery. N Engl J Med. 2004 Jan 1. 350(1):21-8. [QxMD MEDLINE Link].

73. Margolis JR, Chen JT, Kong Y, et al. The diagnostic and prognostic significance of coronary artery calcification. A report of 800 cases. Radiology. 1980 Dec. 137(3):609-16. [QxMD MEDLINE Link].

74. Mark DB, Califf RM, Morris KG, et al. Clinical characteristics and long-term survival of patients with variant angina. Circulation. 1984 May. 69(5):880-8. [QxMD MEDLINE Link].

75. Maseri A, Crea F, Kaski JC, Davies G. Mechanisms and significance of cardiac ischemic pain. Prog Cardiovasc Dis. 1992 Jul-Aug. 35(1):1-18. [QxMD MEDLINE Link].

76. Piatti P, Fragasso G, Monti LD, et al. Endothelial and metabolic characteristics of patients with angina and angiographically normal coronary arteries: comparison with subjects with insulin resistance syndrome and normal controls. J Am Coll Cardiol. 1999 Nov 1. 34(5):1452-60. [QxMD MEDLINE Link].

77. Rocco MB, Nabel EG, Campbell S, et al. Prognostic importance of myocardial ischemia detected by ambulatory monitoring in patients with stable coronary artery disease. Circulation. 1988 Oct. 78(4):877-84. [QxMD MEDLINE Link].

78. Rubins HB, Robins SJ, Collins D, et al. Gemfibrozil for the secondary prevention of coronary heart disease in men with low levels of high-density lipoprotein cholesterol. Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial Study Group. N Engl J Med. 1999 Aug 5. 341(6):410-8. [QxMD MEDLINE Link].

79. Wenger NK, Speroff L, Packard B. Cardiovascular health and disease in women. N Engl J Med. 1993 Jul 22. 329(4):247-56. [QxMD MEDLINE Link].

80. Yusuf S, Sleight P, Pogue J, et al. Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients. The Heart Outcomes Prevention Evaluation Study Investigators. N Engl J Med. 2000 Jan 20. 342(3):145-53. [QxMD MEDLINE Link].

81. Kovarnik T, Chen Z, Mintz GS, et al. Plaque volume and plaque risk profile in diabetic vs. non-diabetic patients undergoing lipid-lowering therapy: a study based on 3D intravascular ultrasound and virtual histology. Cardiovasc Diabetol. 2017 Dec 7. 16(1):156. [QxMD MEDLINE Link].

82. Konigstein M, Giannini F, Banai S. The Reducer device in patients with angina pectoris: mechanisms, indications, and perspectives. Eur Heart J. 2017 Aug 31. [QxMD MEDLINE Link].

83. Her AY, Kim YH, Garg S, Shin ES. Impact of paclitaxel-coated balloon versus newer-generation drug-eluting stent on periprocedural myocardial infarction in stable angina patients. Coron Artery Dis. 2018 Aug. 29 (5):403-8. [QxMD MEDLINE Link].

84. Bu Z, Ma J, Fan Y, et al. Ascending aortic strain analysis using 2-dimensional speckle tracking echocardiography improves the diagnostics for coronary artery stenosis in patients With suspected stable angina pectoris. J Am Heart Assoc. 2018 Jul 7. 7 (14):[QxMD MEDLINE Link].

85. Okada H, Tada H, Hayashi K, et al. Aortic root calcification score as an independent factor for predicting major adverse cardiac events in familial hypercholesterolemia. J Atheroscler Thromb. 2018 Jul 1. 25 (7):634-42. [QxMD MEDLINE Link].

86. Demirtas AO, Karabag T, Demirtas D. Ischemic modified albumin predicts critical coronary artery disease in unstable angina pectoris and non-ST-elevation myocardial infarction. J Clin Med Res. 2018 Jul. 10 (7):570-5. [QxMD MEDLINE Link].