RESUMEN
The authors report the case of an asymptomatic 45 year old man in whom an abnormal origin of the left coronary artery was discovered fortuitously. Coronary angiography was carried out for electrocardiographic signs of anterior myocardial infarction and showed the left coronary artery arising from the pulmonary artery: there was apical dyskinesia with alteration of global left ventricular function. The ostium of the left coronary artery was closed and a saphenous vein aorto-left anterior descending artery bypass was performed. There were no complications. Left ventricular function has not improved 8 months after surgery. The haemodynamic and coronary signs of myocardial ischaemia demonstrated preoperatively regressed after surgery: the coronary "steal" caused by the malformation which led to poor perfusion of the territory of the left coronary artery has therefore been corrected by surgery. This procedure should be carried out as early as possible in order to limit extension of the myocardial lesions.