Acute focal Myocarditis with Preserved Ventricular Function Masquerading as Acute ST-elevation Inferior Wall Myocardial Infarction

Myocarditis is a pathological inflammatory condition which can result in significant damage to the myocardium and more specifically the myocytes. Acute myocarditis can present similarly to myocardial infarction, and can rise to the top of the differential diagnosis when chest pain, cardiac enzymes, and ECG that suggest myocardial infarction are followed by a normal coronary angiogram. The gold standard of diagnosis for myocarditis is an endomyocardial biopsy as a positive biopsy is very specific; however, the inflammation of myocarditis may be diffuse or focal, limiting the biopsy’s sensitivity. We present a case of a 19 year old man with acute focal myocarditis masquerading as an acute ST-elevation inferior wall myocardial infarction on ECG with elevated troponin I. This is an unusual presentation as the patient’s echocardiogram and cardiac catheterization did not show ventricular dysfunction. Our diagnosis was confirmed by cardiac MRI rather than endomyocardial biopsy, due to the high risk of adverse events associated with the latter. Acute myocarditis that mimicks a myocardial infarction in presentation is a rare, but well known occurrence [1]. Acute myocarditis typically presents with a less distinct prodromal illness period, in contrast with fulminant myocarditis, which has a more defined viral prodrome and associated with more severe cardiovascular compromise. Acute myocarditis is also more likely to present in those patients with established ventricular dysfunction, with the potential to progress to dilated cardiomyopathy [2].