Long-Term Study Reveals Comparable Outcomes for iFR and FFR in Coronary Revascularization: DEFINE FLAIR Trial

The DEFINE FLAIR trial initially compared the two approaches in a cohort of patients undergoing revascularization. At the 5-year mark, the study, published in JAMA Cardiology, revealed that an iFR-based strategy was not statistically different from an FFR-based approach in guiding revascularization regarding major adverse cardiovascular events (MACE), nonfatal myocardial infarction, and unplanned revascularization.

Javier Escaned, Hospital Clinico San Carlos IDISSC, Complutense University of Madrid and CIBERCV, Madrid, Spain, and colleagues aimed to compare the long-term outcomes of iFR- and FFR-based strategies for guiding revascularization, noting that the long-term differences between these two approaches remain unclear.

The DEFINE-FLAIR multicenter study randomized patients with coronary artery disease to utilize either iFR or FFR as a pressure index to guide revascularization. Participants were drawn from five continents and had angiographically intermediate severity stenoses, undergoing hemodynamic interrogation with pressure wires. Data for this analysis were collected from March 13, 2014, to April 27, 2021.

The primary outcome measures included five-year major adverse cardiac events (MACE), which is a composite of all-cause death, nonfatal myocardial infarction, and unplanned revascularization, along with the individual components of this combined endpoint.

The following were the key findings of the study:

• At the 5-year follow-up, no significant differences were observed between the iFR group (mean age 65.5 years, 77.5% male) and the FFR group (mean age 65.2 years, 74.3% male) regarding major adverse cardiac events (MACE), with rates of 21.1% for iFR and 18.4% for FFR (hazard ratio [HR], 1.18).
• Although all-cause mortality was slightly higher in the iFR group, this increase was not attributed to myocardial infarction (6.3% in iFR versus 6.2% in FFR; HR, 1.01) or unplanned revascularization (11.9% in iFR versus 12.2% in FFR; HR, 0.98).
• Patients for whom revascularization was deferred based on either iFR or FFR exhibited similar MACE rates (17.9% for iFR versus 17.5% for FFR; HR, 1.03), with comparable rates of individual MACE components, including all-cause death.
• Among those who underwent revascularization following physiological assessment, the incidence of MACE was higher in the iFR group at 24.6%, compared to 19.2% in the FFR group (HR, 1.36).

"The 5-year follow-up results indicated that an iFR-based strategy was not statistically different from an FFR strategy in guiding revascularization concerning major adverse cardiovascular events," the researchers concluded.

Reference:

Escaned J, Travieso A, Dehbi H, et al. Coronary Revascularization Guided With Fractional Flow Reserve or Instantaneous Wave-Free Ratio: A 5-Year Follow-Up of the DEFINE FLAIR Randomized Clinical Trial. JAMA Cardiol. Published online October 16, 2024. doi:10.1001/jamacardio.2024.3314