Quantitative flow ratio and graft outcomes of coronary artery bypass grafting surgery: A retrospective study

Objective: Quantitative flow ratio (QFR) is a novel noninvasive tool for the functional assessment of coronary stenosis. Whether or not QFR could predict graft outcomes after coronary artery bypass grafting procedure is unknown. This study aimed to investigate the association of QFR value with graft outcomes after coronary artery bypass grafting surgery.

Methods: The QFR values were retrospectively obtained from patients receiving coronary artery bypass grafting surgery from 2017 to 2019 in the Graft Patency Between No-Touch Vein Harvesting Technique and Conventional Approach in Coronary Artery Bypass Graft Surgery (PATENCY) trial. QFR calculation was conducted in eligible coronary arteries, defined as those with ≥50% stenosis and a diameter ≥1.5 mm. A threshold of QFR ≤0.80 was considered functionally significant stenosis. The primary outcome was graft occlusion at 12 months evaluated by computed tomography angiography.

Results: Two thousand twenty-four patients with 7432 grafts (2307 arterial grafts and 5125 vein grafts) were included. For the arterial grafts, the risk of 12-month occlusion was significantly increased in the QFR >0.80 group than in the QFR ≤0.80 group (7.1% vs 2.6%; P = .001; unadjusted model: odds ratio, 3.08; 95% CI, 1.65-5.75; fully adjusted model: odds ratio, 2.67; 95% CI, 1.44-4.97). No significant association was observed in the vein grafts (4.6% vs 4.3%; P = .67; unadjusted model: odds ratio, 1.10; 95% CI, 0.82-1.47; fully adjusted model: odds ratio, 1.12; 95% CI, 0.83-1.51). Results were stable across sensitivity analyses with a QFR threshold of 0.78 and 0.75.

Conclusions: Target vessel QFR >0.80 was associated with a significantly higher risk of arterial graft occlusion at 12 months after coronary artery bypass grafting surgery. No significant association was found between target lesion QFR and vein graft occlusion.