Influence of the Geometry of the Left Main Coronary Artery Bifurcation on the Distribution of Sudanophilia in the Daughter Vessels

Abstract

The proximal portions of the left anterior descending (LAD) and left circumflex (LCx) coronary arteries are among the sites most predisposed to atherosclerotic disease. This predisposition might be a consequence of their location immediately distal to the left main (LM) coronary artery bifurcation, which may increase the susceptibility of these segments by promoting an adverse fluid dynamic environment within them. The detailed geometry of the bifurcation influences this environment and would therefore affect the susceptibility of the proximal daughter vessels to disease. This hypothesis was tested by examination of the relationship between the geometry of the LM bifurcation and the distribution of sudanophilia in the proximal portions of the LAD and LCx. The geometric parameters at the LM bifurcation, including all three angles and LM length, were obtained from multiangle photographs of 17 vascular casts by use of objective computer-based algorithms. A robust index, the relative proximal involvement (RPI), was developed to measure the localization of disease to the proximal portions of the daughter vessels. The RPI of the LAD segment correlated best with an interaction term that included the planarity of the LM bifurcation and the LCx-LAD branch angle (P = .013). In addition to supporting the concept of geometric risk factors, these observations also suggest that interactions between the hemodynamic influences of multiple geometric variables may play a role in the mediation of tissue susceptibility by geometric factors.