Pre–Coronary Artery Bypass Grafting Computed Tomography–Based Fractional Flow Reserve Predicts Graft Failure: Implications for Planning Invasive Treatment of Coronary Artery Disease

Abstract

Objective The aim of the study is to evaluate whether a pre–coronary artery bypass grafting (CABG) coronary computed tomography-based fractional flow reserve (FFR-CT) result at the site of a future anastomosis would predict the graft failure in patients undergoing CABG. Methods In 43 patients who had coronary computed tomography angiography (CCTA) prior to the CABG, follow-up CCTA were acquired >12 months post-CABG procedure. The FFR-CT values were simulated on the basis of the pre-CABG CCTA. Based on follow-up CCTA, the anastomosis sites and the graft patency were determined. The graft failure was defined as either its stenosis >50% or occlusion. Results Ninety eight (44 saphenous, 54 left or right internal mammary artery) grafts were assessed. Eighteen grafts from 16 patients were dysfunctional on follow-up CCTA. The FFR-CT values at the location of future anastomosis were higher in dysfunctional than in normal grafts (0.77 [0.71–0.81] vs 0.60 [0.56–0.66], respectively, P = 0.0007). Pre-CABG FFR-CT (hazard ratio = 1.1; 95% CI: 1.012–1.1, P = 0.0230), and bypass graft to right coronary artery (hazard ratio = 3.7; 95% CI: 1.4–9.3 vs left anterior descending artery) were independent predictors of graft dysfunction during follow-up. The optimal threshold of FFR-CT to predict graft failure was >0.68 (sensitivity 88.9% (95% CI: 65.3–98.6), specificity 63.7% (95% CI: 52.2–74.2), positive predictive value 35.6% (95% CI: 28.3%–43.5%), negative predictive value 96.2% (95% CI: 87.2%–99.0%)). Conclusions Pre-CABG functional FFR-CT predicts future coronary bypass graft failure. This shows utility of FFR-CT for guiding coronary revascularization and also suggests significance of physiological assessment prior to CABG.