Optimal Measurement Sites of Coronary-Computed Tomography Angiography-derived Fractional Flow Reserve: The Insight From China CT-FFR Study.

OBJECTIVES: To investigate the optimal measurement site of coronary-computed tomography angiography-derived fractional flow reserve (FFRCT) for the assessment of coronary artery disease (CAD) in the whole clinical routine practice.

MATERIALS AND METHODS: This retrospective multicenter study included 396 CAD patients who underwent coronary-computed tomography angiography, FFRCT, and invasive FFR. FFRCT was measured at 1 cm (FFRCT-1 cm), 2 cm (FFRCT-2 cm), 3 cm (FFRCT-3 cm), and 4 cm (FFRCT-4 cm) distal to coronary stenosis, respectively. FFRCT and invasive FFR ≤0.80 were defined as lesion-specific ischemia. The diagnostic performance of FFRCT to detect ischemia was obtained using invasive FFR as the reference standard. Reduced invasive coronary angiography rate and revascularization efficiency were calculated. After a median follow-up of 35 months in 267 patients for major adverse cardiovascular events (MACE), Cox hazard proportional models were performed with FFRCT values at each measurement site.

RESULTS: For discriminating lesion-specific ischemia, the areas under the curve of FFRCT-1 cm (0.91) as well as FFRCT-2 cm (0.91) were higher than those of FFRCT-3 cm (0.89) and FFRCT-4 cm (0.88), respectively (all P<0.05). The higher reduced invasive coronary angiography rate (81.6%) was found at FFRCT-1 cm than FFRCT-2 cm (81.6% vs. 62.6%, P<0.05). Revascularization efficiency did not differ between FFRCT-1 cm and FFRCT-2 cm (80.8% vs. 65.5%, P=0.019). In 12.4% (33/267) MACE occurred and only values of FFRCT-2 cm were independently predictive of MACE (hazard ratio: 0.957 [95% CI: 0.925-0.989]; P=0.010).

CONCLUSIONS: This study indicates FFRCT-2 cm is the optimal measurement site with superior diagnostic performance and independent prognostic role.