Objectives: The aim of this study was to assess clinical outcomes after combined pressure and flow assessment of coronary lesions.

Background: Although fractional flow reserve (FFR) remains the invasive reference standard for revascularization, approximately 40% of stenoses have discordant coronary flow reserve (CFR). Optimal treatment for these disagreements remains unclear.

Methods: A total of 455 subjects with 668 lesions were enrolled from 12 sites in 6 countries. Only lesions with reduced FFR and CFR underwent revascularization; all other combinations received initial medical therapy.

Results: Fourteen percent of lesions had FFR<=0.8 but CFR>=2.0 while 23% of lesions had FFR>0.8 but CFR<2.0. During 2-year follow-up, the primary endpoint of composite all-cause death, myocardial infarction, and revascularization in lesions with FFR<=0.8 but CFR>=2 (10.8% event rate) compared with lesions with FFR>0.8 and CFR>=2 (6.2% event rate) exceeded the prespecified +10% noninferiority margin (P = 0.090). Target vessel failure models using both continuous FFR and continuous CFR found that only higher FFR was associated with reduced target vessel failure (Cox P = 0.007) after initial medical treatment. Central core laboratory review accepted 69.8% of all tracings with mean differences of <0.01 for FFR and <0.02 for CFR, indicating no material impact on clinical measurements or outcomes.

Conclusions: All-cause death, myocardial infarction, and revascularization after 2 years was not noninferior between lesions with FFR<=0.8 but CFR>=2 and lesions with FFR>0.8 and CFR>=2. These results do not support using invasive CFR>=2 to defer revascularization for lesions with reduced FFR if the patient would otherwise be a candidate on the basis of the entire clinical scenario and treatment preference.