From the Guidelines
Myocarditis should be diagnosed and treated promptly, with hospitalization recommended for patients with definite myocarditis that is either mild or moderate in severity, ideally at an advanced heart failure center, as stated in the 2022 ACC Expert Consensus Decision Pathway 1. The diagnosis of myocarditis is based on a combination of clinical symptoms, elevated cardiac biomarkers, and abnormal electrocardiographic, echocardiographic, and/or cardiac magnetic resonance (CMR) findings.
- Common symptoms of myocarditis include chest pain, shortness of breath, fatigue, heart palpitations, and fever.
- Initial testing should consist of an ECG, measurement of cardiac troponin (cTn), and an echocardiogram, with CMR recommended in hemodynamically stable patients with suspected myocarditis 1.
- Treatment depends on the cause and severity of myocarditis, but generally includes rest, medication to reduce inflammation, and heart medications such as ACE inhibitors or beta-blockers to reduce heart workload.
- Severe cases may require corticosteroids, immunosuppressants, or intravenous immunoglobulin therapy, with intravenous corticosteroids considered in those with suspected or confirmed COVID-19 myocarditis with hemodynamic compromise or MIS-A 1.
- Patients with myocarditis and COVID-19 pneumonia with ongoing need for supplemental oxygen should be treated with corticosteroids, and those with associated pericardial involvement may be treated with nonsteroidal anti-inflammatory drugs, colchicine, or prednisone 1.
- Guideline-directed medical therapy for heart failure should be initiated and continued after discharge, with strenuous physical activity avoided for 3-6 months during recovery to prevent complications 1.
From the Research
Definition and Causes of Myocarditis
- Myocarditis is a potentially fatal condition that occurs when inflammation of the heart musculature causes cardiac dysfunction 2.
- It may result from common viral infections, toxic or hypersensitivity drug reactions, giant-cell myocarditis, or sarcoidosis 3.
- The most common causes of myocarditis are viruses, such as influenza and coronavirus, systemic autoimmune disorders, drugs, and vaccines 4.
Symptoms and Diagnosis of Myocarditis
- Symptoms may range from mild to severe and are often preceded by a viral prodrome 2.
- Myocarditis may present with a wide range of symptoms, ranging from mild dyspnea or chest pain to cardiogenic shock and death 3.
- Approximately 82% to 95% of adult patients with acute myocarditis present with chest pain, while 19% to 49% present with dyspnea, and 5% to 7% with syncope 4.
- Laboratory assessment, electrocardiogram, and echocardiography can be helpful for the diagnosis, but cardiac magnetic resonance imaging or endomyocardial biopsy are required for definitive diagnosis 2, 4.
Treatment and Management of Myocarditis
- Treatment is primarily focused on respiratory and hemodynamic support 2.
- Initial hemodynamic management includes vasopressors and inotropes, whereas more severe cases may require an intra-aortic balloon pump, extracorporeal membrane oxygenation, or a ventricular assist device 2.
- Immunosuppression (eg, corticosteroids) is appropriate for patients who have myocarditis characterized by eosinophilic or giant cell myocardial infiltrations or due to systemic autoimmune disorders 4.
- First-line therapy depends on acuity, severity, clinical presentation, and etiology and includes supportive care 4.
Prognosis and Complications of Myocarditis
- Myocarditis is a serious condition with the potential for significant morbidity and mortality 2.
- Dilated cardiomyopathy with chronic heart failure is the major long-term sequela of myocarditis 3.
- Approximately 75% of patients admitted with myocarditis have an uncomplicated course, with a mortality rate of approximately 0% 4.
- Acute myocarditis that is complicated by acute heart failure or ventricular arrhythmias is associated with a 12% rate of either in-hospital mortality or need for heart transplant 4.