Background: Atherosclerotic occlusion of a coronary vessel is the commonest causeof ischaemic heart disease. The distribution of atherosclerotic lesions is not random,with stenoses preferentially situated at branch ostia, bifurcation points, and theproximal segments of daughter vessels. The aim of this study was to determinethe effect of the intrinsic anatomical properties of the left main coronary artery(LMCA) on the distribution of atherosclerotic lesions in its branches.

Materials and methods: A retrospective review of 170 consecutive coronaryangiograms obtained from the cardiac catheterisation laboratories of privatehospitals in the eThekwini Municipality area of KwaZulu-Natal, South Africa wasperformed. The LMCA was absent in 19/170 (11.2%). The remaining angiograms(n = 151) were divided into two groups: normal 63/151 (41.7%) and those withcoronary artery disease (CAD) 88/151 (58.3%). The CAD group was sub-dividedinto proximal 42/88 (47.7%), mixed (proximal and distal) 26/88 (29.6%) and distal20/88 (22.7%) sub-groups based on the location of atherosclerotic lesions in thebranches of the LMCA.

Results and Conclusions: The mean length, diameter and angle of division of theLMCA were as follows: Total angiograms: 10.4 mm, 3.8 mm and 86.2o; normal group:10.5 mm, 3.9 mm and 85.7o, CAD group: 10.2 mm, 3.7 mm and 86.3o; proximalsub-group: 10.9 mm, 3.7 mm and 91.6o, mixed sub-group — 9.8 mm, 3.7 mm and85o and distal sub-group — 9.1 mm, 3.8 mm and 79.4o, respectively. The vessels withproximally located lesions were recorded to have longer lengths and wider anglesof division than vessels with distal lesions. Coronary angiographic delineation of theLMCA anatomy may be predictive of a coronary arterial arrangement that may favourthe progression of proximally located lesions.