Computational fluid dynamics analysis of the relationship between wall shear stress pattern and plaque distribution at the distal left main bifurcation area

Abstract

Purpose: Atherosclerosis in distal left main coronary artery (LMCA) preferentially propagates to left anterior descending artery (LAD) rather than left circumflex artery (LCX). The mechanism, however, of it has not been well investigated. Methods: We used computational fluid dynamics (CFD) to assess the relationship between wall shear stress (WSS) and plaque distribution at distal LMCA bifurcation area (n=270 segments) in patients with chest pain. Multislice computed tomography was used for the initial screening test followed by coronary angiography and virtual histology intravascular ultrasound. Vascular numerical analysis, including WSS, was performed in 6 regions: distal LMCA, proximal LAD, proximal LCX, outer wall of LMCA to proximal LAD (zone 1), outer wall of LMCA to proximal LCX (zone 2), and the flow divider (carina, zone 3) (Figure). ![Figure][1] Results: Peak and average WSS significantly decreased in zones 1 than zone 2 or zone 3 (3.05±2.16, 4.83±3.19, 8.91±7.59, Pa, p<0.001; 0.98±0.94, 1.73±1.33, 3.60±2.95, Pa, p<0.001, respectively). Peak and average WSS were also significantly decreased in distal LMCA than proximal LAD or LCX (4.10±2.55, 5.71±4.79, 7.29±5.23, Pa, p=0.003; 1.41±1.00, 2.21±1.94, 2.84±2.11, p=0.002, Pa, respectively). Persistent lower peak WSS in zone 1 was observed irrespective of plaque type, bifurcation angle, and LCX vessel size (Figure). Conclusions: Regardless of bifurcation angle degree, plaque type, and LCX vessel size, a significantly lower WSS pattern at zone 1 may contribute to the mechanism of predominant plaque distribution more often found originating in LCMA and distributing to proximal LAD rather than LCX. [1]: pending:yes