Abstract 14887: Look Beyond the Coronaries: A Rare Cause of Acute Papillary Muscle Rupture

Abstract

A 63-year-old male with numerous cardiac risk factors presented with two hours of rapidly progressing chest pain and shortness of breath. Exam was notable for respiratory distress requiring non-invasive mechanical ventilation and a holosystolic apical murmur radiating to the axilla. He had an elevated troponin and an electrocardiogram with anteroseptal ST depressions. He was diagnosed with a non-ST segment elevation acute coronary syndrome and taken for cardiac catheterization. Surprisingly, no occlusive epicardial disease was discovered. Left ventriculogram revealed engorgement of the left atrium and pulmonary arteries suggestive of severe mitral regurgitation. The mechanism of mitral regurgitation was unclear until transesophageal echocardiography showed a ruptured posteromedial papillary muscle with flail mitral valve, a picture classically caused by myocardial infarction. Cardiac MRI demonstrated preserved LV function with minor inferior apical hypokinesis, nonspecific endocardial late gadolinium enhancement in the inferior segments, and a small LV thrombus. An embolic myocardial infarction targeting a small territory involving posteromedial papillary muscle was thought most probable. The patient then underwent an uneventful mitral valve replacement and recovery. However, he returned two months later with severe biventricular dysfunction and cardiogenic shock with peripheral eosinophilia. Myocardial biopsy confirmed the diagnosis of eosinophilic myocarditis. An exhaustive workup for the etiology of his eosinophilia proved unrevealing; he was consequently diagnosed with the idiopathic subtype. The case highlights a rare but important clinical entity that has a varied phenotype. Our patient presented atypically with an acute papillary muscle rupture that mimicked an acute myocardial infarction, ultimately delaying diagnosis. As evidenced by our case, clinical suspicion of myocarditis should be high in all patients presenting with typical anginal symptoms with mechanical or circulatory compromise in the absence of acute coronary occlusion.