Improved diagnostic accuracy of vessel-specific myocardial ischemia by coronary computed tomography angiography (CCTA).

Background: Discrepancies between stenosis severity assessed at coronary computed tomography angiography (CCTA) and ischemia might depend on vessel type. Coronary plaque features are associated with ischemia. Thus, we evaluated the vessel-specific correlation of CCTA-derived diameter stenosis (DS) and invasive fractional flow reserve (FFR) and explored whether integrating morphological plaque features stratified by vessel might increase the predictive yield in identifying vessel-specific ischemia.

Methods: Observational cohort study including patients undergoing CCTA for suspected coronary artery disease, with at least one vessel with DS ​≥ ​50 ​% at CCTA, undergoing invasive coronary angiography and FFR. Plaque analysis was performed using validated semi-automated software. Coronary vessels were stratified in left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA). Per vessel independent predictors of ischemia among CCTA-derived anatomical and morphologic plaque features were tested at univariable and multivariable logistic regression analysis. The best cut-off to predict ischemia was determined by Youden's index. Ischemia was defined by FFR≤0.80.

Results: The study population consisted of 192 patients, of whom 224 vessels (61 ​% LAD, 19 ​% LCX, 20 ​% RCA) had lesions with DS ​≥ ​50 ​% interrogated by FFR. Despite similar DS, the rate of FFR≤0.80 was higher in the LAD compared to LCX and RCA (67.2 ​% vs 43.2 ​% and 44.2 ​%, respectively, p ​= ​0.018). A significant correlation between DS and FFR was observed only in LAD (p ​= ​0.003). At multivariable analysis stratified by vessel, the vessel-specific independent predictors of positive FFR were percent atheroma volume (threshold>17 ​%) for LAD, non-calcified plaque volume (threshold >130 ​mm³) for LCX, and lumen volume (threshold <844 ​mm³) for RCA. Integrating DS and vessel-specific morphological plaque features significantly increased the predictive yield for ischemia compared to DS alone (AUC ranging from 0.51 to 0.63 to 0.76-0.80).

Conclusions: Integrating DS and vessel-specific morphological plaque features significantly increased the predictive yield for vessel-specific ischemia compared to DS alone, potentially improving patients' referral to the catheterization laboratory.