NORMAL LEFT MAIN CORONARY-ARTERY DIAMETER CAN BE PREDICTED FROM DIAMETERS OF ITS BRANCH VESSELS

An uncommon though vexing problem exists when the left main coronary a rtery appears subjectively to be diffusely stenotic relative to its br anch vessels, but the severity of such stenosis cannot be determined b ecause of the lack of a normal reference. To overcome this problem, 20 coronary angiograms demonstrating no evidence of disease were quantit atively analyzed to determine the normal ratio of left main diameter t o the sum of the diameters of its immediate branches. For bifurcating left mains, the mean ratio of diameter of left main to sum of diameter s of its two immediate branches was 0.65 +/- 0.04; for trifurcating le ft mains, the mean ratio of diameter of left main to sum of diameters of its three immediate branches was 0.56 +/- 0.02. Thus, it appears fe asible and practical to predict the normal diameter of the left main f rom the measured diameters of its immediate branches.