Incremental value of physiological indices to predict high-risk plaques detected by NIRS-IVUS.

Identification of vulnerable plaques is important for reducing future cardiovascular events. This study aimed to investigate optimal modalities other than intravascular imaging in evaluating vulnerable plaques. We prospectively evaluated 105 non-culprit coronary lesions by CCTA imaging and near-infrared spectroscopy-intravascular ultrasound in 32 patients with acute coronary syndrome. Angiographically-derived ΔQFR and ΔFFR were measured as the difference in QFR and FFR across the stenosis. A receiver operating characteristic curve analysis was performed to determine the optimal cutoff values of angiographically- and CCTA-derived plaque features for a maxLCBI ≥ 400. The best cutoff values for ΔQFR and ΔFFR to predict a maxLCBI ≥ 400 were 0.05 and 0.06, respectively. ΔQFR and ΔFFR values and percent diameter stenosis on QCA or CCTA were associated with a maxLCBI ≥ 400 (both P < 0.05). The combination of ΔFFR ≥ 0.06 and plaque density predicted a maxLCBI ≥ 400 with 89.4% sensitivity and 84.5% specificity (area under the curve, 0.90; P < 0.0001). There was no significant difference in area under the curve values between ΔQFR and plaque density + ΔFFR ≥ 0.06 (0.92 vs. 0.90, P = 0.50). In the diagnosis of vulnerable plaques in acute coronary syndrome, the combination of ΔFFR and plaque density shows a diagnostic capability similar to that of ΔQFR in non-culprit lesions.