Hypoplastic coronary artery disease: A rare cause of sudden cardiac death and its treatment with an implantable defibrillator.

A 21-year-old African American male presented to the emergency department after an episode of unexplained syncope. He had no significant past medical history. The initial physical examination was within normal limits, and his 12-lead electrocardiogram showed no signs of ischemia or evidence of chamber enlargement. The patient received a transthoracic echocardiogram which demonstrated mild global left ventricular dysfunction with an estimated ejection fraction of 45%. Coronary angiography was next performed and found no evidence of atherosclerotic coronary artery disease but did reveal hypoplasia of the left circumflex and right coronary arteries, with intraluminal diameters of approximately 1 mm. The left anterior descending coronary artery was small distally. Cardiac magnetic resonance imaging with gadolinium enhancement found no evidence of myocardial scar. The patient was ultimately diagnosed with aborted sudden cardiac death due to hypoplastic coronary artery disease (HCAD). The patient received an implantable cardioverter-defibrillator (ICD) prior to hospital discharge for secondary prevention of sudden cardiac death. One year after this presentation, the patient has been asymptomatic, with no ICD discharges.