Acute total occlusion of the left main coronary artery with emphasis on electrocardiographic manifestations.

Survival from sudden total occlusion of the left main coronary artery is rare. The majority of these patients suffer major myocardial necrosis accompanied by cardiogenic shock. Case reports and small series of acute left main occlusion present descriptions of electrocardiographic (ECG) changes during the acute phase. Severe ischemia may be manifested in the ECG by life-threatening tachyarrhythmias, conduction disturbances and ST-segment deviation. Because of the potential for life-saving therapeutic options by emergency bypass grafting or immediate stenting, the ECG markers of the serious condition should be recognized by the medical profession. Acute left main occlusion should be suspected in severely ill patients with wide-spread ST-segment depressions, especially in the lateral precordial leads with inverted T waves or ST elevation involving the anterior precordial leads and the lateral extremity leads I and aVL. Also, lead aVR ST elevation accompanied by either anterior ST elevation or widespread ST-segment depression, may indicate left main occlusion. However, as other ECG manifestations have been reported, the absence of these changes should not exclude immediate invasive evaluation of hemodynamically compromised patients. The exact electrophysiological and pathophysiological background for different ECG manifestations of left main occlusion need to be better defined.