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.