A 17-year-old male presented for outpatient cardiology review with palpitations and infrequent chest pain. There were no exertional symptoms, and there was no history of syncope or dyspnea. The patient had a twin brother who died within 24 hours of birth, reportedly after being born with severe congenital anomalies including a single lung. There was no family history of cardiac disease and no family history of sudden cardiac death. Cardiovascular examination on presentation was unremarkable, resting ECG demonstrated sinus bradycardia (heart rate, 56 bpm) with no significant abnormalities, and a 24-hour period of continuous cardiac monitoring did not demonstrate any sustained arrhythmias. Transthoracic echocardiography demonstrated mildly increased left ventricular size by volume criteria with preserved systolic function and no left ventricular hypertrophy. Mild mitral regurgitation was present. Continuous turbulent systolic and diastolic flow was noted at the lateral wall of the left ventricle draining into a cavity within the anterolateral papillary muscle (Figure 1; Movie I in the Data Supplement). The findings were consistent with an anomalous coronary-cameral fistula. During an exercise stress echocardiogram, the patient exercised for 12 minutes and was symptom free with no arrhythmias and no electrical or echocardiographic evidence of ischemia.