Acute Myocardial Infarction Due to Fixed Coronary Artery Stenosis From Myocardial Bridging

Myocardial bridging is a common coronary abnormality often associated with left ventricular hypertrophy. It can be noted incidentally on coronary angiography by findings of systolic narrowing of the involved coronary artery. We present the case of a 59-year-old woman that presented with a non-ST elevation myocardial infarction. She had a history of angina and workup 9-months prior with CT coronary angiography that revealed an intra-myocardial course of the left anterior descending coronary artery (LAD) with minimal stenosis and no concomitant coronary artery disease. Invasive coronary angiography now demonstrated apparent myocardial bridging associated with a severe fixed stenosis of the LAD without change in diameter with nitroglycerin injection. Due to persistent symptoms, surgical myotomy was attempted and then aborted because of difficulty unroofing the LAD due to surrounding fibrosis. Coronary artery bypass grafting (CABG) was then successfully performed using a left internal mammary artery graft. The patient had complete resolution of her chest pain and was without functional limitation at 3-month follow-up. This case highlights possible sequelae of myocardial bridging and suggests that, in rare cases, fixed obstruction of the involved coronary artery may occur in the setting of fibrosis of the bridged segment. In such cases, surgical myotomy may not be feasible and CABG may be required.