Fulminant Myocarditis Clinical Practice Guidelines (AHA, 2020)

The scientific statement on recognition and initial management of fulminant myocarditis (FM) was released in January 2020 by the American Heart Association (AHA).[1,2] The recommendations are the first of its kind for managing FM and outline the resources necessary to manage the spectrum of FM, including extracorporeal life support, percutaneous and durable ventricular assist devices, transplantation capabilities, and specialists in advanced heart failure, cardiothoracic surgery, cardiac pathology, immunology, and infectious disease. The primary message is for frontline providers—primary emergency room doctors and hospitalists—to recognize cardiogenic shock early and refer patients to specialists or centers that have the capability to support patients through mechanical support or transplants.

Working Definition of Fulminant Myocarditis

FM is defined as “a sudden and severe inflammation of the myocardium resulting in myocyte necrosis, edema, and cardiogenic shock.”

Diagnostic Red Flags

The following are suggestive of the presence of FM:

The presence of "apparent cardiovascular (CV) conditions," such as acute coronary syndrome or de novo acute heart failure, in a young patient

History of signs/symptoms of recent viral upper respiratory tract infection or enteroviral infection presenting with CV symptoms in young patients without typical CV risk factors

The presence of shock, electric instability, or rapidly evolving conduction abnormalities (eg, widening QRS complex or PR prolongation)

Signs/symptoms of right-sided heart failure (eg, right upper quadrant pain, liver function test abnormalities, jaundice, hepatomegaly with liver pulsatility, distended neck veins, peripheral edema)

Early recognition of circulatory compromise (eg, narrow arterial pulse pressure, sinus tachycardia, cool/mottled extremities, elevated lactate levels)

Initial Tests

Initial tests that should be conducted in the emergency department (ED) for patients with suspected early FM who are hemodynamically stable include the following:

Electrocardiography (ECG)

Chest x-ray

Complete blood cell (CBC) count with differential

Basic metabolic panel

Levels of creatine kinase-MB (CK-MB), creatine phosphokinase (CPK), cardiac troponin (cTn)

Natriuretic peptide levels (B-type natriuretic peptide [BNP] or N-terminal proBNP [NT-proBNP])

Arterial blood gas (ABG) or venous blood gas (VBG), lactate level

Liver function tests

Blood cultures (for febrile patients)

Initial ED Management

Treat cardiogenic shock and cardiac arrest in patients with FM according to the AHA’s guideline for advanced cardiac life support (ACLS).

Avoid treatment of sinus tachycardia with rate control agents (particularly those with negative inotropic properties, such as metoprolol, diltiazem, or verapamil).

Avoid giving intravenous fluids to hypotensive patients because they can worsen symptoms and hemodynamics in the setting of an acute heart failure syndrome or cardiogenic shock.

Avoid nonsteroidal anti-inflammatory agents (NSAIDs), which have the potential to increase sodium retention, cause myocardial harm, and exacerbate renal hypoperfusion.

Vasopressor therapy with norepinephrine has been found to be superior to dopamine in the setting of acute myocardial infarction (AMI) shock (fewer arrhythmias with norepinephrine), although the effect of its use in FM is unknown. In addition, in the setting of cardiogenic shock related to an AMI, norepinephrine had improved survival compared with dopamine.

Use early invasive management to rule out epicardial coronary disease and measure hemodynamics.

Endomyocardial biopsy may reduce the time of end-organ and brain hypoperfusion and decrease time to the specific diagnosis of the cause of FM that may have a specific treatment.

Hemodynamic support is necessary for initial stabilization, and respiratory support is often required to maintain adequate tissue perfusion and end-organ delivery. Thus, mechanical circulatory support (MCS) devices or extracorporeal life support (ECLS) may be required.

Patients without the need for extracorporeal oxygenation can receive percutaneous biventricular assist devices, which have the benefit of eliminating some risks associated with ECLS, as well as the need for an oxygenator. An added advantage is that these percutaneous assist devices can provide biventricular unloading, which decreases myocardial wall stress, thus lessening potential exacerbation of injury to an already inflamed heart.

Following stabilization, it is recommended that all patients with FM and contractile dysfunction—regardless of the disease pathogenesis—be treated with evidence-based neurohormonal antagonist therapy.

The guidelines also discuss four major myocarditis subtypes that result in a fulminant presentation (fulminant lymphocytic myocarditis, giant cell myocarditis, acute necrotizing eosinophilic myocarditis, immune checkpoint inhibitor myocarditis), along with their microscopic findings (hematoxylin/eosin stain), clinical manifestations, and treatment.

References

1 Kociol RD, Cooper LT, Fang JC, et al, for the American Heart Association Heart Failure and Transplantation Committee of the Council on Clinical Cardiology. Recognition and initial management of fulminant myocarditis: a scientific statement from the American Heart Association. Circulation. 2020 Jan 6:CIR0000000000000745. https://www.ahajournals.org/doi/pdf/10.1161/CIR.0000000000000745

2 Swift Yasgur B. New AHA statement on management of fulminant myocarditis. Medscape Medical News. January 13, 2020. Available at: https://www.medscape.com/viewarticle/923721. Accessed January 29, 2020.