Background. Low coronary artery wall shear stress (WSS) promotes atherogenesis. Intravascular ultrasound (IVUS) studies of distal left main coronary artery (LMCA) lesions have shown that 90% have plaque from the LMCA to the left anterior descending (LAD), 65% have plaque from the LMCA into the left circumflex (LCX), and that the carina is rarely diseased (Circ Cardiovasc Interv. 2010;3:105-12). Methods. We used using computational fluid dynamics (CFD) to assess WSS and plaque distribution at the distal LMCA bifurcation in 23 consecutive pts. Coronary computed tomography (CT) was the initial screening test followed by coronary angiography and Virtual Histology Intravascular Ultrasound (VH-IVUS). Vascular numerical analysis assisted by computer-aided design measured WSS in 3 regions; [1] LM into proximal LAD, [2] LMCA into proximal LCX, and [3] flow divider (carina). VH-TCFA was defined as necrotic core >10% of plaque area within a plaque burden of >40% and >30째 abutting the lumen in >3 consecutive frames. Results. Eighteen pts were amenable for WSS analysis. As shown in the Figure, peak WSS tended to be lower from LMCA into proximal LAD than from LMCA into proximal LCX (p=0.055) and was lower from distal LMCA into either proximal LAD or LCX than at the flow divider (p=0.001 and p=0.01, respectively). In 5 pts with VH-LM-TCFA, WSS was low and similar in both the LAD and LCX (3.66짹3.61 Pa in LAD vs 4.23짹2.79 Pa in LCX, p=0.399), but was higher in one side of the LMCA bifurcation than the other (10 LCX and 3 LAD) in non-TCFA. Conclusion. CFD calculation of WSS accurately predicts reported patterns of atherosclerotic plaque distribution at the distal LMCA bifurcation and may be associated with VH-TCFA distribution.