Association Between Adherence to Fractional Flow Reserve Treatment Thresholds and Major Adverse Cardiac Events in Patients With Coronary Artery Disease

Abstract

Importance: Fractional flow reserve (FFR) is an invasive measurement used to assess the potential of a coronary stenosis to induce myocardial ischemia and guide decisions for percutaneous coronary intervention (PCI). It is not known whether established FFR thresholds for PCI are adhered to in routine interventional practice and whether adherence to these thresholds is associated with better clinical outcomes.

Objective: To assess the adherence to evidence-based FFR thresholds for PCI and its association with clinical outcomes.

Design, setting, and participants: A retrospective, multicenter, population-based cohort study of adults with coronary artery disease undergoing single-vessel FFR assessment (excluding ST-segment elevation myocardial infarction) from April 1, 2013, to March 31, 2018, in Ontario, Canada, and followed up until March 31, 2019, was conducted. Two separate cohorts were created based on FFR thresholds (≤0.80 as ischemic and >0.80 as nonischemic). Inverse probability of treatment weighting was used to account for treatment selection bias.

Exposures: PCI vs no PCI.

Main outcomes and measures: The primary outcome was major adverse cardiac events (MACE) defined by death, myocardial infarction, unstable angina, or urgent coronary revascularization.

Results: There were 9106 patients (mean [SD] age, 65 [10.6] years; 35.3% female) who underwent single-vessel FFR measurement. Among 2693 patients with an ischemic FFR, 75.3% received PCI and 24.7% were treated only with medical therapy. In the ischemic FFR cohort, PCI was associated with a significantly lower rate and hazard of MACE at 5 years compared with no PCI (31.5% vs 39.1%; hazard ratio, 0.77 [95% CI, 0.63-0.94]). Among 6413 patients with a nonischemic FFR, 12.6% received PCI and 87.4% were treated with medical therapy only. PCI was associated with a significantly higher rate and hazard of MACE at 5 years compared with no PCI (33.3% vs 24.4%; HR, 1.37 [95% CI, 1.14-1.65]) in this cohort.

Conclusions and relevance: Among patients with coronary artery disease who underwent single-vessel FFR measurement in routine clinical practice, performing PCI, compared with not performing PCI, was significantly associated with a lower rate of MACE for ischemic lesions and a higher rate of MACE for nonischemic lesions. These findings support the performance of PCI procedures according to evidence-based FFR thresholds.

Figure 1.. Cohort Creation

Selection of patients undergoing single-vessel fractional flow reserve (FFR) of non–left main lesions between April 1, 2013, and March 31, 2018, is presented. The final cohort contained 9106 unique individuals. CABG indicates coronary artery bypass grafting; PCI, percutaneous coronary intervention; and STEMI, ST-elevation myocardial infarction.

Figure 2.. Major Adverse Cardiac Events After Percutaneous Coronary Intervention (PCI)

The cumulative incidence of major adverse cardiac events in the propensity-weighted cohorts of patients is overlaid and depicted. Curves depict the incidence of events in patients with an ischemic fractional flow reserve (FFR) who had PCI (median follow-up, 3.08 years; interquartile range [IQR], 1.96-4.34) and did not have PCI (median follow-up, 2.77 years; IQR, 1.72-4.15) and with a nonischemic FFR who had PCI (median follow-up, 3.41 years; IQR, 2.18-4.73) and did not have PCI (median follow-up, 2.98 years; IQR, 1.87-4.31). The number at risk in the weighted samples is depicted for each group. Major adverse cardiac events were defined by death, myocardial infarction, unstable angina, or urgent coronary revascularization.