P6178The optimal point of CT-FFR measurement in comparison with invasive FFR

Abstract

Abstract Background Currently, invasive fractional flow reserve (FFR), has become a gold standard to select patients requiring revascularization. Coronary computed tomography angiography (CTA) -derived FFR (FFRCT/CT-FFR) can be used for the management of coronary artery disease, which would be a gatekeeper of invasive coronary angiography. In most of the previous report to evaluate the diagnostic performance of FFRCT/CT-FFR, FFRCT/CT-FFR value was measured at the same point as the invasive FFR. Clinically, FFRCT/CT-FFR should be measured without the information of invasive FFR. However, optimal measurement point for CT-FFR has not been established yet. Purpose To assess the optimal measurement point of CT-FFR in comparison with invasive FFR as a gold standard. Methods CTA images scanned at 70–99% of R-R interval with 320 slice CT were screened. In the de-novo lesions with invasive FFR data were included in this study. Since calcified lesions could affect CT-FFR value, severe calcified lesions on CTA were excluded from the analysis. The CT-FFR analysis was performed by 2 cardiologists blinded to the results of the invasive FFR using a standard desktop computer and dedicated software. CT-FFR values could be provided at any point from ostium of coronary artery to the distal with vessel diameter of 1.8mm. To determine the optimal point for measurement of CT-FFR, CT-FFR values were obtained at 3 points in each coronary artery; 1) at the same point as invasive FFR; 2) lowest CT-FFR at distal point of coronary artery; 3) at 2.0 cm distal to the lesion. The diagnostic performance at each point was compared with invasive FFR. Results Fifty vessels of 44 patients (average age 68 years, male were 32) were included. Average Agatston score was 279.4. There was significant correlation between CT-FFR at each point and invasive FFR. CT-FFR at the same point as invasive FFR showed the good correlation with invasive FFR (R=0.641, 95% CI= 0.041–0.127, p<0.0001). Compared to the lowest CT-FFR at distal (R=0.608, 95% CI= 0.069–0.160, p<0.0001), CT-FFR at 2.0 cm distal to the lesion (R=0.604, 95% CI= 0.007–0.061, p<0.0001) revealed better correlation with invasive FFR. Sensitivity, specificity, positive and negative predictive value at each point were 92.8 / 93.3 / 81.8; 75.0 / 57.1 / 94.2; 61.9 / 48.2 / 60.0; and 96.0 / 95.2 / 84.6, respectively. Diagnostic accuracy showed that CT-FFR at 2cm distal to the lesion (0.84) was similar to CT-FFR at the same point as invasive FFR (0.80), and it was better than far distal (0.68) to detect invasive FFR derived ischemia. Conclusions CT-FFR was feasible to detect invasive FFR derived ischemia at the same point. CT-FFR at 2.0 cm distal to the lesion showed higher diagnostic performance compared with CT-FFR measured at the far distal. CT-FFR measurement at 2.0 cm distal to the lesion would be a optimal position clinically.