Diagnosis and Treatment of Acute Myocarditis

Abstract

ImportanceAcute myocarditis, defined as a sudden inflammatory injury to the myocardium, affects approximately 4 to 14 people per 100 000 each year globally and is associated with a mortality rate of approximately 1% to 7%.ObservationsThe most common causes of myocarditis are viruses, such as influenza and coronavirus; systemic autoimmune disorders, such as systemic lupus erythematosus; drugs, such as immune checkpoint inhibitors; and vaccines, including smallpox and mRNA COVID-19 vaccines. 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. The diagnosis of myocarditis can be suggested by presenting symptoms, elevated biomarkers such as troponins, electrocardiographic changes of ST segments, and echocardiographic wall motion abnormalities or wall thickening. Cardiac magnetic resonance imaging or endomyocardial biopsy are required for definitive diagnosis. Treatment depends on acuity, severity, clinical presentation, and etiology. Approximately 75% of patients admitted with myocarditis have an uncomplicated course, with a mortality rate of approximately 0%. In contrast, 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. Approximately 2% to 9% of patients have hemodynamic instability, characterized by inability to maintain adequate end-organ perfusion, and require inotropic agents, or mechanical circulatory devices, such as extracorporeal life support, to facilitate functional recovery. These patients have an approximately 28% rate of mortality or heart transplant at 60 days. Immunosuppression (eg, corticosteroids) is appropriate for patients who have myocarditis characterized by eosinophilic or giant cell myocardial infiltrations or due to systemic autoimmune disorders. However, the specific immune cells that should be targeted to improve outcomes in patients with myocarditis remain unclear.Conclusions and RelevanceAcute myocarditis affects approximately 4 to 14 per 100 000 people per year. First-line therapy depends on acuity, severity, clinical presentation, and etiology and includes supportive care. While corticosteroids are often used for specific forms of myocarditis (eg, eosinophilic or giant cell infiltrations), this practice is based on anecdotal evidence, and randomized clinical trials of optimal therapeutic interventions for acute myocarditis are needed.

Key Predictors of Outcome in Patients With Fulminant Myocarditis Supported by Venoarterial Extracorporeal Membrane Oxygenation

“…This is a major limitation of the study. 4 In this cohort, in-hospital mortality of patients with FM requiring peripheral VA-ECMO was 34.9%. Despite a mean age of 41 years, only 1.9% were escalated to heart transplantation and 2.4% to an LV assist device.…”

“…5 Furthermore, giant cell myocarditis and eosinophilic myocarditis respond to immunosuppression, whereas the role of immunosuppression is still under debate in the case of lymphocytic myocarditis. 2,4 This could explain why patients undergoing an EMB had a higher survival without needing an heart transplantation or longterm LV assist device at 90 days than those who did not (70% versus 56%, respectively, P=0.009) in the CHANGE PUMP 2 Study. 6 However, EMB may be performed in more stable patients and at more experienced (high-output) centers, introducing a potential selection bias that could explain the demonstrated benefit.…”

“…Furthermore, other retrospective registries have not found an association between immunosuppressive therapy and outcome among patients with FM. [4][5][6] Potential explanations for the lack of evidence for immunosuppression beyond lack of benefit may be late administration of the therapy or bias. It may be that corticosteroids in retrospective registries are a marker of more severe myocarditis.…”

“…gov; Unique identifier: NCT05150704) is an ongoing international investigator-initiated randomized controlled trial assessing efficacy of 1 g methylprednisolone for 3 days versus placebo. 4,15 Nunez et al nicely demonstrate that mortality in VA-ECMO-supported patients with FM is significantly higher in older and heavier patients with a more fulminant initial presentation (extracorporeal cardiopulmonary resuscitation, pre-ECMO sepsis, lower mean arterial pressure, and pH/lactate levels). This suggests that patients are best pulled back from the negative spiral of cardiogenic shock if t-MCS is initiated early after the recognition of FM (Figure).…”

“…cute myocarditis presenting with cardiogenic shock, also termed fulminant myocarditis (FM), 1,2 represents 3% to 9% of adult patients admitted with acute myocarditis. 3,4 Peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO) is an established means of temporary mechanical circulatory support (t-MCS) that has improved survival of patients with FM. 1,2 Nevertheless, patients requiring VA-ECMO still have an extremely high mortality.…”