Impact of Epicardial plaQUe Composition and geomeTry on Coronary hEmodynamics and Flow in Patients With Coronary Artery Disease (iEquate).

Invasive coronary physiology including fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and coronary flow reserve (CFR) are guideline-endorsed tools to guide the management of coronary artery disease (CAD). Complex factors impact and confound these assessments, and discordance between modalities complicates clinical management. iEquate is a prospective observational trial that combines multi-modality coronary physiology and optical coherence tomography (OCT) to identify the determinants of pressure-wire derived myocardial ischemia and iFR-FFR discordance. All patients referred for invasive angiography who met the pre-selection criteria were screened for inclusion and exclusion criteria. Patients underwent physiological assessment using iFR and FFR, and CFR was performed as indicated. OCT was performed on all suitable lesions. Data were collected on baseline demographics, angiographic results, OCT findings, coronary physiology, and procedural details. Multivariate analysis was performed. A total of 124 vessels were analyzed from 107 patients. The mean age was 67.6 ( ± 10.8) years, and 23 patients (21.5%) were female. Eighty (74.8%) presented with stable angina, and the most common vessel assessed was the left anterior descending artery (n = 84, 67.7% of patients). The incidence of iFR-FFR discordance was 20.7%, with 48% of these iFR+FFR-. Calcific plaque was associated with discordance (OR 6.15 [95% CI [1.05-36.13]; p = 0.04), largely with a iFR+FFR- pattern (OR 7.62 [95% CI 0.38-152.15]; p = 0.184). Other morphological features were not predictive of FFR, iFR, or CFR findings. Mean CFR was significantly lower in the iFR+FFR- subgroup compared to FFR+iFR- (mean difference 1.4; p < 0.01). iFR-FFR discordance is common, and impaired vasodilatory capacity (assessed using CFR) may account for some of these cases. In this study, calcific plaque was associated with discordance, while other OCT-derived plaque morphological characteristics were not associated with invasive coronary physiology findings. Cross-sectional plaque eccentricity is associated with lower FFR values.