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Published on: November 24, 2014
Limited performance questions retrospective use of quantitative flow ratio in coronary artery bypass grafting
Hannes Abfalterer1, Dominik Janker1, Lorenz Rüf1
1Department of Cardiac Surgery, Medical University of Innsbruck, Innsbruck, Austria.
Insights
Quantitative flow ratio (QFR) predicts arterial graft patency in coronary artery bypass grafting. However, retrospective QFR analysis showed low feasibility and poor diagnostic performance, limiting its clinical application.
Area of Science:
- Cardiovascular Medicine
- Interventional Cardiology
- Medical Imaging Analysis
Background:
- Arterial graft patency is crucial for long-term outcomes after coronary artery bypass grafting (CABG).
- Hemodynamic assessment of coronary artery stenosis can impact graft survival.
- Quantitative flow ratio (QFR) is a method to assess coronary artery stenosis hemodynamics.
Purpose of the Study:
- To evaluate the association between QFR of native coronary target vessels and postoperative arterial graft patency.
- To assess the feasibility and diagnostic performance of retrospective QFR analysis in patients with prior CABG.
Main Methods:
- Retrospective analysis of 596 patients with prior CABG and at least one arterial graft.
- Preoperative angiography used for retrospective QFR analysis of native coronary target vessels.
- Coronary targets with QFR ≤0.80 defined as hemodynamically relevant; >0.80 as irrelevant.
Main Results:
- Higher arterial graft patency rates observed for grafts anastomosed to coronary branches with QFR ≤0.80 (p=0.017).
- QFR ≤0.80 was an independent predictor of arterial graft patency (HR: 0.475, p=0.015).
- Retrospective QFR analysis had low feasibility (80.22% of target vessels not analysable) and poor diagnostic performance (AUC=0.595).
Conclusions:
- While QFR ≤0.80 is associated with improved arterial graft patency, its retrospective application is limited by low feasibility and diagnostic performance.
- Caution is advised when using retrospective QFR in similar datasets due to observed constraints.
Background:
Hemodynamic assessment of coronary artery stenosis has impact on arterial graft patency. Quantitative flow ratio (QFR) obtains hemodynamic information of coronary artery stenosis.
Methods:
Patients with history of isolated coronary artery bypass grafting (with ≥1 arterial graft) and at least one postoperative coronary re-assessment were retrospectively investigated. The preoperative angiography was used for retrospective QFR analysis of the native coronary target vessel, to which the arterial bypass graft was anastomosed. Analysis was performed by certified investigators, who were blinded towards postoperative arterial graft patency status. Coronary targets with QFR values of ≤0.80 were defined as hemodynamically relevant, whereas values of >0.80 were defined as hemodynamically irrelevant.
Results:
Out of 5,692 patients, 596 patients had a postoperative coronary assessment and were therefore eligible for inclusion. In 196 arterial target vessels QFR analysis was possible. Kaplan-Meier analysis revealed higher graft patency rates for arterial grafts anastomosed to coronary branches with QFR values ≤0.80 (log-rank: p = 0.017). In multivariable Cox regression analysis, QFR ≤ 0.80 remained an independent predictor for arterial graft patency (HR: 0.475, 95% CI: 0.261-0.867; p = 0.015), while visually estimated stenosis from preoperative coronary angiography did not (p = 0.160). With an area under the curve of 0.595, 95% CI (0.503-0.688), the performance of the model was poor to at most moderate. Most target vessels [546 (80.22%)] were not analysable in retrospective fashion.
Conclusion:
Though target vessel QFR ≤ 0.80 was associated with higher arterial graft patency, our trial observed low feasibility (high drop out rates) and poor diagnostic performance of QFR used in retrospective fashion. Caution is warranted for retrospective use of QFR in datasets with similar constraints.
