Abstract 11836: A Rare Cause of Recurrent Myocardial Infarction: Genetic Testing Cracks the Case

Abstract

A 29-year-old man presented to our institution with acute, severe substernal chest pain. An ECG on arrival revealed 3mm ST-elevations in the lateral leads with reciprocal depressions in the inferior leads. Troponin-I was above assay (>50 ng/mL). Emergent coronary angiography showed normal coronary arteries, and left ventriculogram showed no wall motion abnormalities. A transthoracic echocardiogram showed normal biventricular size, wall thickness, and ejection fraction (EF). This was his fifth episode of chest pain over the past 10 years, consistent with prior presentations of ST-elevation myocardial infarction and angiographically normal coronary arteries. A prior cardiac magnetic resonance imaging (MRI, 6 years before the current presentation) revealed increased T2 signal intensity and subepicardial late gadolinium enhancement (LGE) in the septum, inferior, and inferolateral walls, suggestive of nonischemic acute myocardial injury. A repeat cardiac MRI during the current presentation showed mildly reduced biventricular systolic function (LVEF 52%, RVEF 36%), and again showed increased T2 signal intensity and subepicardial LGE involving the septum, inferior and inferolateral walls. The anterior and anterolateral walls were also now involved. Endomyocardial biopsy (EMB) showed focal interstitial fibrosis with no evidence of active myocarditis. On telemetry he was noted to have runs of non-sustained ventricular tachycardia (NSVT). Serologic evaluation was negative for parvovirus, cytomegalovirus, and Chagas disease. Erythrocyte sedimentation rate and C-reactive protein levels were normal. Genetic testing was performed at our newly established cardiovascular genetics program, which showed a pathogenic truncating mutation in the desmoplakin gene (DSP). DSP cardiomyopathy (CM) is an LV-predominant arrhythmogenic CM, which can present with episodic myocardial injury, and has a high disposition for ventricular arrhythmias with subepicardial LGE pattern often proceeding LV systolic dysfunction. A primary prevention implantable cardioverter-defibrillator was placed given extent of LGE and NSVT burden in the context of DSP variant. This case illustrates the importance of genetic testing in identifying rare CM phenotypes.