Myocarditis

Background

• Myocarditis is an inflammation of the myocardium secondary to pathologic immune processes that are triggered by a variety of underlying etiologies (such as infection [including HIV and Zika], autoimmune disease, drug reactions, or peripartum syndromes).

Evaluation

• Suspect myocarditis in patients with new-onset myocardial injury resulting in electrical or mechanical abnormalities in cardiac function in absence of acute coronary syndromes or other causes.
• Patients commonly present with nonspecific symptoms including chest pain, dyspnea, and palpitations.
• Myocarditis is often part of a pancarditis involving the epicardium, pericardium, and endocardium and may present with pericarditis, worsening heart failure, atrial or ventricular arrhythmias, valvular dysfunction, heart block, cardiogenic shock, or sudden cardiac death.
• Perform an echocardiography to assess ventricular size and function to rule out other causes of cardiac dysfunction (Strong recommendation).
• Consider obtaining cardiac magnetic resonance (CMR) to distinguish ischemic from nonischemic cardiomyopathy.
• Consider measuring serum biomarkers such as cardiac troponin where elevated levels are supportive but not diagnostic of myocarditis.
• Perform an endomyocardial biopsy in patients with (Strong recommendation):
  • new-onset heart failure of < 2 weeks with normal-sized or dilated left ventricle and hemodynamic compromise (suspected fulminant lymphocytic myocarditis)
  • new-onset heart failure of 2 weeks to 3 months with dilated left ventricle and new ventricular arrhythmias, second- or third-degree heart block, or failure to respond to usual care in 1-2 weeks (suspected giant cell myocarditis)

Management

• Provide standard pharmacologic and supportive medical care for a patient presenting with heart failure (Strong recommendation).
• Do not routinely use immunosuppressive therapy (Strong recommendation).
• Consider a trial of immunosuppressive therapy for children and patients with (Weak recommendation):
  • giant cell myocarditis
  • autoimmune or hypersensitivity myocarditis
  • severe hemodynamic compromise and deteriorating conditions
  • cardiac sarcoidosis
  • eosinophilic myocarditis
  • nonviral myocarditis
• Refer patients with suspected myocarditis to a specialty center (Strong recommendation).
• Refer patients for cardiac transplantation evaluation or mechanical circulatory support if they have:
  • heart failure and evidence of end-organ damage or progressive deterioration (refer urgently) (Strong recommendation)
  • severe heart failure despite standard heart failure therapy (Strong recommendation)