Long-Term Outcomes After Fractional Flow Reserve vs Intravascular Ultrasound to Guide PCI: The FLAVOUR Trial Extended Follow-Up

Abstract

Background: The optimal treatment strategy for patients with intermediate coronary stenosis remains uncertain.

Objectives: The aim of this study was to investigate the long-term outcomes of a randomized, open-label, multinational trial comparing fractional flow reserve (FFR)-guided vs intravascular ultrasound (IVUS)-guided treatment strategies.

Methods: Patients aged ≥19 years with de novo intermediate coronary stenosis (40%-70%) and target vessel diameters ≥2.5 mm were randomized 1:1 to FFR- or IVUS-guided treatment across 18 sites in Korea and China. The primary endpoint was a composite of all-cause death, myocardial infarction, and any revascularization occurring after the index procedure. Secondary endpoints included individual components of the primary outcome and per vessel outcomes according to treatment type. Extended follow-up continued through September 2024.

Results: Between July 2016 and August 2019, 1,682 patients were assigned to the FFR-guided (n = 838) and IVUS-guided (n = 844) groups. Over a median follow-up period of 6.3 years (Q1-Q3: 5.6-6.9 years), the primary outcome occurred in 339 patients (22.0%), with no statistically significant difference between groups (179 [23.1%] for FFR vs 160 [20.9%] for IVUS; HR: 1.15; 95% CI: 0.93-1.42; P = 0.208). The revascularization rate after the index procedure was higher in the FFR group (113 [14.9%] vs 87 [11.8%]; HR: 1.32; 95% CI: 1.00-1.75; P = 0.049), particularly for target vessel revascularization (72 [9.6%] vs 44 [6.2%]; HR: 1.67; 95% CI: 1.15-2.43; P = 0.007). Landmark analysis at 2 years and per vessel analyses indicated that the higher revascularization rate after the index procedure was driven primarily by late (2-7 years) revascularizations in vessels in which percutaneous coronary intervention (PCI) was initially deferred. Nevertheless, the overall rate of target vessel PCI, including procedures at index and during follow-up, was significantly lower in the FFR group (38.8% vs 60.5%; P < 0.001), with no statistically significant differences in the annual cumulative incidence of death or myocardial infarction between groups.

Conclusions: FFR-guided and IVUS-guided treatment strategies resulted in comparable long-term outcomes, with no significant difference in patient-oriented composite outcomes. Although FFR-guided treatment was associated with a higher incidence of late target vessel revascularization, the overall target vessel PCI rate, accounting for both the index procedure and revascularization during follow-up, remained significantly lower in the FFR-guided treatment group, with comparable rates of hard outcomes between the 2 groups.

Keywords: coronary artery disease; fractional flow reserve; intravascular ultrasound; long-term outcomes; percutaneous coronary intervention.