Coronary artery fistula as a bypass of a left anterior descending coronary artery stenosis.

We present a case of coronary artery fistula originating from the proximal left anterior descending coronary artery anterior to a critical atheromatous stenosis, draining into the main trunk of the pulmonary artery and with a third branch draining into the coronary vessel itself, distal to the lesion. The diagnosis was made when we were performing a diagnostic coronary arteriography on a patient with unstable angina. The possible association of the fistula and coronary atherosclerosis is discussed.