Severe cardiomyopathy caused by a critically stenosed anomalous left coronary artery ostium originating in the left ventricle

We report a case of a 44‐year‐old patient presenting with new‐onset severe decompensated congestive heart failure, which was refractory to aggressive inpatient medical treatment. Left ventricular ejection fraction was 16%. Radiological investigations revealed the presence of an anomalous subannular origin of the left coronary artery, with an associated 95% ostial stenosis. The artery was supplied by collaterals from the right coronary system. This included a proximal collateral from the right marginal artery, which had its own separate ostium in the right aortic sinus. A diagnosis of ischemic dilated cardiomyopathy was made. The patient successfully underwent urgent coronary artery bypass grafting with a view to improve his left ventricular function and congestive heart failure symptoms.