Functional Assessment Using QFR for the Revascularization of Non-Culprit Lesions in AMI Patients

Nowadays, evidence from studies and meta-analyses has demonstrated the benefits of complete revascularization compared to culprit-vessel-only revascularization in patients with acute myocardial infarction (AMI). The identification and treatment of non-culprit lesions can be guided by conventional angiography, intracoronary imaging, or coronary physiology; the optimal modality, however, is still unclear.

Quantitative flow ratio (QFR) is a type of functional assessment derived from angiography that doesn’t require a coronary guidewire. Various studies have assessed this tool, including FAVOR III (Functional Assessment by Virtual Online Reconstruction), which demonstrated that QFR-based revascularization reduces the incidence of major cardiovascular events. However, the role of QFR in treating non-culprit lesions in AMI patients remains uncertain.

The objective of this multicenter, randomized study was to assess the predictive capability of QFR for adverse events and to evaluate the non-inferiority of QFR-guided management for treating non-culprit lesions.

The primary endpoint (PEP) was a composite of cardiac death, target vessel myocardial infarction (TVMI), and ischemia-driven target vessel revascularization (id-TVR). The secondary endpoint (SEP) included the individual components of the PEP.

The FIRE (Functional Assessment in Elderly MI Patients With Multivessel Disease) study randomized 1145 AMI patients into two groups: culprit-vessel-only revascularization (n=725) and complete physiology-guided revascularization (n=720). The mean age of the participants was 81 years, and most subjects were men. The most frequent clinical presentation was non-ST segment elevation MI (about 60%), followed by ST segment elevation MI.

The most frequently affected vessel was the left anterior descending artery, followed by the right coronary artery, the circumflex artery, and the left main coronary artery. QFR was measured in 903 non-culprit vessels of 685 patients in the culprit-only group. In total, 366 (40.5%) of the non-culprit vessels showed a QFR value ≤0.80, with a significantly higher incidence of the PEP (22.1% vs. 7.1%; P <0.001).

A QFR ≤0.80 emerged as an independent predictor of the PEP (hazard ratio [HR]: 2.79; 95% confidence interval [CI]: 1.64-4.75). In the complete revascularization group, QFR was used in 320 (35.2%) non-culprit vessels to guide revascularization. There were no significant differences in the PEP when comparing the treatments of non-culprit vessels guided by QFR-based functional assessment (HR: 0.57; 95% CI: 0.28-1.15).

Conclusion

This study demonstrated that QFR can be safely used to identify non-culprit lesions requiring revascularization in AMI patients with multivessel disease.