Dimensions and anatomic variations of left main coronary artery in normal population: multidetector computed tomography assessment

OBJECTIVES: The aim of our study was to determine the dimensions, morphology and anatomic variations of the left main coronary artery (LMCA) in normal participants, on multidetector computed tomography. BACKGROUND: Accurate imaging of LMCA dimensions and configuration is crucial to avoid misdiagnosis of LMCA disease. MATERIALS AND METHODS: Seventy morphologically normal LMCAs of 70 participants were carefully selected from among 600 consecutive coronary computed tomography angiography studies performed in our institute. LMCA cross-sectional diameters and areas were obtained at three points of each vessel: ostium, midvessel and distal. The length, cross-sectional shape, three-dimensional (3D) morphology and position of origin were studied. Influences of age, body weight, height and body surface area (BSA) on LMCA dimensions were evaluated. RESULTS: Different dimensions in each measured point of the LMCA were detected. Cross-sectional elliptic shape at ostium, mid-LMCA and distal LMCA was found in 66/70 (94%), 51/70 (73%) and 54/70 (77%) of the participants, respectively. On the basis of the 3D presentation, four types of LMCA were identified: biconcave-shape appearance (type 1), tapering morphology (type 2), combined morphology (type 3) and funnel-shape appearance (type 4). Fifty-two of the 70 participants had an LMCA orifice originating in the middle third of the aortic sinus, 15/70 in the posterior third and 3/70 in the anterior third. In men, significant correlation was found between LMCA cross-sectional area and body weight, height and BSA. In women, no correlation was found regarding body weight, height and BSA. CONCLUSION: LMCA is not a simple straight tube but usually has various anatomical configurations, variable dimensions and cross-sectional shapes. Ostial angulation is a normal variant usually associated with the posterior position of the LMCA orifice of origin in the aortic sinus.