Fractional Flow Reserve and Fractional Flow Reserve Gradient From CCTA for Predicting Future Coronary Events

Background: Coronary computed tomography angiography–derived fractional flow reserve (FFR_CT) is a per-vessel index reflecting cumulative hemodynamic burden while coronary events occur in focal lesions. Objectives: The authors sought to evaluate the additive prognostic value of the local gradient of FFR_CT (FFR_CT gradient) in addition to FFR_CT to predict future coronary events. Methods: The current study included 245 patients (634 vessels) who underwent coronary computed tomography angiography within 6 to 36 months before the index angiography, of which 209 vessels had future coronary events and 425 vessels did not. Future coronary events were defined as a composite of vessel-specific myocardial infarction or urgent revascularization during a mean interval of 1.5 years. Pre-existing disease patterns were classified according to FFR_CT of ≤0.80 and FFR_CT gradient of ≥0.025/mm. Results: Both FFR_CT (per 0.01 decrease; adjusted HR: 1.040; 95% CI: 1.029-1.051; P < 0.001) and FFR_CT gradient (per 0.01 increase; adjusted HR: 1.144; 95% CI: 1.101-1.190; P < 0.001) were significantly associated with the risk of future coronary events. Lesions with FFR_CT gradient of ≥0.025/mm showed significantly higher risk of future coronary events than those with FFR_CT gradient of <0.025/mm in both the FFR_CT >0.80 (49.2% vs 30.1%; HR: 2.069; 95% CI: 1.265-3.385; P = 0.004) and FFR_CT ≤0.80 groups (60.9% vs 38.3%; HR: 1.988; 95% CI: 1.317-2.999; P =0 .001). Adding FFR_CT gradient into the model with FFR_CT alone showed significantly increased predictability of future coronary events (global chi-square: 45.8 vs 39.9; P = 0.015). Conclusions: Patients with high FFR_CT gradient showed increased risk of future coronary events irrespective of FFR_CT. Integrating both FFR_CT and FFR_CT gradient showed incremental predictability of future coronary events compared with FFR_CT alone.