Long-Term Clinical Outcomes of Nonhyperemic Pressure Ratios: Resting Full-Cycle Ratio, Diastolic Pressure Ratio, and Instantaneous Wave-Free Ratio

Abstract

Background: Nonhyperemic pressure ratios (NHPRs) such as instantaneous wave-free ratio, resting full-cycle ratio, or diastolic pressure ratio have emerged as invasive physiologic indices precluding the need for hyperemic agents. The current study sought to evaluate the long-term prognostic implications of NHPRs compared with fractional flow reserve (FFR).

Methods and Results: NHPRs were calculated from resting pressure tracings by an independent core laboratory in 1024 vessels (435 patients). The association between NHPRs and the risk of 5-year vessel-oriented composite outcomes (VOCO, a composite of cardiac death, vessel-related myocardial infarction, and ischemia-driven revascularization) were analyzed among 864 deferred vessels. Lesions with positive NHPRs (instantaneous wave free ratio, resting full-cycle ratio, and diastolic pressure ratio ≤0.89) or FFR (≤0.80) showed significantly higher risk of VOCO at 5 years than those with negative NHPRs or FFR, respectively. Discriminant ability for 5-year VOCO was not different among NHPRs and FFR (C-index: 0.623-0.641, P for comparison=0.215). In comparison of VOCO among the groups with deferred concordant negative (NHPRs-/FFR-), deferred discordant (NHPRs+/FFR- or NHPRs-/FFR+), and revascularized vessels, the cumulative incidence of VOCO were 7.5%, 14.4%, and 14.8% (log-rank P<0.001), respectively. The deferred discordant group showed similar risk of VOCO with the revascularized vessel group (hazard ratio, 0.981; 95% CI 0.434-2.217, P=0.964).

Conclusions: Currently available invasive pressure-derived indices showed similar prognostic implications for vessel-related events at 5 years. Deferred lesions with discordant results between NHPRs and FFR did not show higher risk of vessel-related events at 5 years than revascularized vessels.