Assessment of Guidewire-Induced Deviation in Fractional Flow Reserve: Impact of Lesion Morphology and Pressure Guidewire Malposition.

Coronary artery disease (CAD) is one of the leading causes of mortality worldwide. Fractional flow reserve (FFR) is a diagnostic metric for evaluating ischemic coronary stenoses, necessitating invasive pressure measurements using a guidewire during maximal hyperemia. The stenosis morphology and the presence of a guidewire influence coronary hemodynamics, warranting further investigation to improve FFR accuracy. This study systematically examines the effect of a pressure guidewire on FFR across different stenosis morphologies under clinically relevant boundary conditions (BCs). Six idealized models of coronary stenosis were developed, representing area stenoses (AS: percentage reduction in the cross-sectional area) of 64%, 75%, 84%, and 91%, based on the dimensions of the left anterior descending (LAD) artery. Computational fluid dynamics (CFD) simulations were conducted using coronary BCs validated against both in vivo and in silico data in the literature. Guidewire-induced FFR deviation (dFFR) exhibited a linear correlation with the blockage ratio-guidewire area relative to minimum lumen area-with deviations exceeding 0.04 for AS greater than 80%. dFFR values were comparable for AS of 64% and 75% across different shapes, but shape-related variation increased (> 0.02) at AS of 84% and 91%. Lesion length (LL) significantly influenced FFR based on morphology: a threefold increase in LL reduced FFR by 0.06 in crescent-shaped stenosis, while having minimal impact in the fully eccentric circular case (AS 84%). However, dFFR remained largely unaffected by LL. Finally, the effects of guidewire malposition on dFFR were negligible in non-circular stenoses (< 0.01) but considerable in circular stenoses (> 0.04 for AS 84%).