Geometry-Dependent Wall Shear Stress in Standardized 50% Coronary Stenoses: Effects of Pressure and Hematocrit in a Parametric CFD Study

Angiographically equivalent coronary lesions may not produce equivalent local biomechanical environments. This study tested whether a standardized stenosis generates different wall shear stress (WSS) distributions across geometries under matched pressure conditions. Steady-state computational fluid dynamics simulations used idealized left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) models derived from human morphometric parameters. Each contained a 50% diameter-reduction stenosis, 18 mm long and 35% eccentric. Diastolic pressures of 70, 90, and 130 mmHg and hematocrit levels of 25%, 45%, and 65% were evaluated using hematocrit-dependent effective Newtonian properties and a distal-to-proximal pressure ratio of 0.86. Blood flow was modeled under steady-state conditions with rigid arterial walls. A patient-derived LAD was included as a secondary analysis. At 130 mmHg and 65% hematocrit, WSS at the corresponding principal stenotic point reached 88.79 Pa in the RCA, 52.21 Pa in the LAD, and 32.18 Pa in the LCX. Changes in the prescribed hematocrit-dependent effective blood properties produced different WSS responses across the geometries. The patient-derived LAD showed comparable relative WSS responses. Thus, in these simulations, equivalent stenosis and pressure ratios did not produce biomechanically equivalent WSS environments. These findings indicate that artery-specific geometry contributes to local wall-shear exposure. Its potential relevance to plaque vulnerability and coronary risk should be assessed in future patient-specific studies incorporating plaque characteristics and clinical outcomes.