Diagnostic Approach to Myocarditis in the Critical Care Unit

Abstract

Acute myocarditis refers to inflammation of the myocardium that can result from multiple etiologies, including viral infection, bacterial infections, tick-borne diseases, and systemic inflammatory disorders such as acute kidney injury, sarcoidosis, and systemic lupus erythematosus. In addition, myocarditis is difficult to distinguish from other conditions causing cardiac symptoms, electrocardiographic changes, myocardial enzyme release, and left ventricular dysfunction such as sepsis, pulmonary embolism, and other causes of heart failure. Although its prevalence in critically ill patients is unknown, acute myocarditis likely occurs far more commonly than recognized. While most often presenting without symptoms, myocarditis may progress rapidly to fulminant heart failure, arrhythmias, and sudden cardiac death. The diagnosis can be difficult due to the lack of specificity of test findings, particularly in the intensive care and coronary care unit setting. Magnetic resonance imaging has emerged as an important imaging modality but is sometimes impractical for critically ill patients. Endomyocardial biopsy has been used less commonly because of relatively high complication rates, sampling error, and wide interobserver variability in interpretation of histology findings.