Background
Coronary artery bypass graft (CABG) surgery is often the revascularization method of choice for patients with multi-vessel disease. Graft patency is influenced by patient factors and surgical technique. Among these different factors, competitive flow in the bypassed coronary arteries is a strong predictor of graft occlusion, impacting long-term outcomes. The more stenosed the native vessel, the less competitive flow there is, making it crucial to bypass only vessels with significant stenoses. Fractional flow reserve (FFR) is a widely used method for this purpose, and literature shows that lower FFR values in the native vessels correlate with higher grat patency rates. Non-invasive methods like three- dimensional coronary models and angiography-derived FFR software, such as Medis Quantitative Flow Ratio® (QFR®), offer cost-effective and accurate alternatives to invasive assessments. This study examines the ability of QFR® to predict long-term graft patency.
Method
Patients who underwent CABG preceded by coronary angiography at CHUV between January 2012 and December 2021 were enrolled if they had a subsequent coronary angiography after CABG. Patients data, including clinical and surgical details, were collected from medical records. Preoperative coronary angiographies were analyzed using Medis QFR® software to assess the severity of native vessel stenoses. Patency was then assessed based on follow-up angiography reports. In a sub-groupe analysis, patients were divided into two groups based on whether they only underwent a CABG surgery, or also a concomitant valve surgery.
Results
In total, 92 patients with 198 grafted vessels were included. Among these, 164 vessels were analyzable. QFR® was not a significant predictor of graft patency, with no statistical difference between occluded and patent vessels (0.70 vs 0.69, P = 0.5449). Similar results were observed for both isolated and combined surgery groups.
Conclusion
In this study, QFR® was not a significant predictor of graft patency, but several limitations are to consider such as the small sample size, affecting statistical power. Despite this, the study demonstrates the technical feasibility of QFR® in these vessels, a notable finding given the retrospective design. Future studies with larger cohorts and longer follow-up are needed to validate these findings and further explore QFR’s clinical utility.