QFR for the Revascularization of Nonculprit Vessels in MI Patients: Insights From the FIRE Trial

Background The role of quantitative flow ratio (QFR) in the treatment of nonculprit vessels of patients with myocardial infarction (MI) is a topic of ongoing discussion. Objectives This study aimed to investigate the predictive capability of QFR for adverse events and its noninferiority compared to wire-based functional assessment in nonculprit vessels of MI patients. Methods The FIRE (Functional Assessment in Elderly MI Patients With Multivessel Disease) trial randomized 1,445 older MI patients to culprit-only (n = 725) or physiology-guided complete revascularization (n = 720). In the culprit-only arm, angiographic projections of nonculprit vessels were prospectively collected, centrally reviewed for QFR computation, and associated with endpoints. In the complete revascularization arm, endpoints were compared between nonculprit vessels investigated with QFR or wire-based functional assessment. The primary endpoint was the vessel-oriented composite endpoint (VOCE) at 1 year. Results QFR was measured on 903 nonculprit vessels from 685 patients in the culprit-only arm. Overall, 366 (40.5%) nonculprit vessels showed a QFR value ≤0.80, with a significantly higher incidence of VOCEs (22.1% vs 7.1%; P < 0.001). QFR ≤0.80 emerged as an independent predictor of VOCEs (HR: 2.79; 95% CI: 1.64-4.75). In the complete arm, QFR was used in 320 (35.2%) nonculprit vessels to guide revascularization. When compared with propensity-matched nonculprit vessels in which treatment was guided by wire-based functional assessment, no significant difference was observed (HR: 0.57; 95% CI: 0.28-1.15) in VOCEs. Conclusions This prespecified subanalysis of the FIRE trial provides evidence supporting the safety and efficacy of QFR-guided interventions for the treatment of nonculprit vessels in MI patients. (Functional Assessment in Elderly MI Patients With Multivessel Disease [FIRE]; NCT03772743)