Impact of preoperative quantitative flow ratio on long term coronary artery bypass grafts patency

Abstract Background Preoperative fractional flow reserve (FFR) in the native coronaries is a known predictor of long-term graft patency after coronary artery bypass graft (CABG) surgery. Quantitative flow ratio (QFR) is an angiogram-based functional assessment tool of coronary stenoses. Its predictive value of graft patency is unknown. Purpose To investigate the impact of preoperative QFR value on long-term graft patency after CABG. Methods In this retrospective multicentric study we included consecutive patients treated with CABG between 2011 and 2022, with available coronary angiogram before and at any timepoint after CABG. Three-vessel QFR analysis of the preoperative angiography has been performed. Follow-up angiography was checked for graft patency. Only vessels entered the analysis for which baseline QFR was appropriate and which has been bypassed. Results 400 patients were included with mean age of 67±8 years. They received on average 2.0±0.9 bypasses. 788 coronaries and bypasses were analyzed, among the latter 455 were arterial and 333 were veins. 37% were placed on LAD, 26% on RCA and 26% on the LCx. Stenosis severity at baseline was 73±22% with a QFR value of 0.68±0.30. Follow-up angiographies were performed at 34±29 months. Overall graft patency was 83%, with higher occlusion rate for venous than arterial conduits (27% vs 9%, respectively; HR 3.9 [2.60-5.88]). Occlusion rate was lower for grafts implanted on QFR significant native vessels versus those, placed on non-significant ones (13% vs 30%, respectively; HR 2.86 [1.93-4.26]). Benefit was maintained for both, arterial (5% vs 22%, respectively; HR 5.23 [2.78-10.38]), as well as for venous conduits (24% vs 39%; HR 2.09 [1.21-3.50]). Conclusion QFR significantly predicts graft patency irrespective of whether the graft is arterial or venous. However, patency of venous grafts is poor, even if implanted on functionally significant native stenotic coronaries.Graft patency