A comprehensive approach combining FFR, CFR, and IMR in order to predict adverse cardiovascular events in patients with non-obstructive coronary artery disease

Abstract Background Abnormal coronary circulation is linked to poor patient outcomes. The predictive values of comprehensive physiological assessments in patients with non-obstructive coronary artery disease (NOCAD) have not been fully investigated. Objectives The study aimed to evaluate the predictive value of a comprehensive approach that combines fractional flow reserve (FFR), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR) in patients with NOCAD. Methods FFR, CFR, and IMR were measured in the left anterior descending artery of 226 patients with NOCAD. The primary endpoint was defined as adverse cardiovascular events including cardiovascular death, heart failure, coronary revascularization, cerebral infarction, and peripheral vascular events. Results Optimal cutoffs predicting the endpoint were 0.89 for FFR, 2.3 for CFR and 18.0U for IMR. Among the patients, 53 were negative for all indices, 80 positive for one, and 93 positive for two or three. During a median follow-up period of two years, 29 adverse events occurred, with the distribution as follows: 1 (1.9%) in patients with all negative indices, 5 (6.2%) in those with one positive index, and 23 (24.7%) in those with two or three positive indices. Kaplan-Meier curve analysis demonstrated significantly worse event-free survival in patients with an increasing number of positive indices (χ2=18.5, P<0.001). The presence of two or three positive indices was an independent predictor of the endpoint (hazard ratio 7.280, p<0.001). Conclusions Combining FFR, CFR, and IMR is an effective method for predicting cardiovascular events in patients with NOCAD.