Left main coronary artery dissection during cardiac catheterization.

: A 70-year-old man with a downward sloping origin of the left main coronary artery developed left main dissection at coronary angiography and died despite emergency coronary by-pass surgery. Autopsy showed that the left main coronary artery had an acute angle take off and dissection had originated at the junction of the superior wall of the left main and the aorta. The combination of left main stenosis secondary to dissection and severe right coronary atherosclerosis had caused circumferential subendocardial left ventricular infarction. The left main coronary artery had mild atherosclerosis and lacked cystic medial necrosis. An angulated left main coronary artery may be a risk factor for dissection at angiography.