Physiology guided coronary revascularization using a hybrid RFR-FFR strategy for Non ST elevation acute coronary syndrome

To develop a hybrid resting full-cycle ratio (RFR)- fractional flow reserve (FFR) decision-making approach for physiology-guided coronary revascularization in patients with non-ST elevation acute coronary syndrome (NSTE-ACS). This study comprised 253 NSTE-ACS patients (with 320 diseased vessels) who underwent invasive physiological evaluation at Cangzhou Central Hospital of Hebei Medical University between September 2021 and August 2023. The FFR threshold of ≤ 0.80 served as the reference standard for diagnosing functional coronary ischemia. Through exploratory analysis, a hybrid RFR-FFR method was developed to identify the "gray zones" of RFR measurements. The thresholds were set to reflect the upper boundary of high negative predictive values and the lower boundary of high positive predictive values, ensuring over 95.00% agreement with the FFR-alone methodology. Adenosine was employed solely for lesions with RFR values falling within these predefined thresholds, while the proportion of cases that could avoid adenosine in the hybrid model was quantified. When the concordance rate between the hybrid RFR-FFR model and the FFR-alone model reached 95.31%, adenosine use decreased significantly, showing a 56.56% reduction in vasodilator administration, coupled with positive and negative predictive values of 96.28% and 93.33%, respectively. As the zone requiring adenosine broadened, the correlation between the hybrid and FFR-alone strategies was strengthened, though the proportion of adenosine-free diseased vessels showed a corresponding decrease. The width of the adenosine requirement zone was 0.04 RFR points (0.89-0.92) and 0.07 RFR points (0.87-0.93) at the 90% and 95.31% agreement (concordance rate with FFR-only classification) levels, respectively. The hybrid RFR-FFR decision-making approach has the potential to reduce adenosine dependence in some patients while maintaining a high degree of consistency with the FFR alone decision-making approach. With the expansion of the adenosine requirement zone, the correlation between the hybrid strategy and the FFR-alone strategy further improved.