Predictive value of combining the SYNTAX score with reactive hyperemia index in patients with acute coronary syndrome undergoing percutaneous coronary intervention

OBJECTIVE: To investigate the predictive value of SYNTAX (Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) score (SS) combined with reactive hyperemia index (RHI) in predicting 2-year major adverse cardiovascular events (MACE) in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). BACKGROUND: Both SS and RHI are good predictors of MACE; however, it is unknown whether combining SS and RHI could improve predictability of MACE in patients with ACS undergoing PCI. METHODS: We undertook a prospective study in 401 ACS patients that underwent PCI. The RHI-SYNTAX score (RSS) was calculated by categorizing and summing up the RHI and SS of individual patients. Patients with RHI < 1.67 are given 1 point, RHI ≥ 1.67 given 0 points, and those with SS ≤ 22 scored as 0 and SS > 22 as 1 point. Patients were classified into three groups: low RSS (group 0), moderate RSS (group 1), and high RSS (group 2). RESULTS: Among patients in the low, moderate, and high groups, the 2-year rates of MACE were 5.50, 10.66, and 23.33%, respectively (p < .0001). Total revascularization rates were 1.83, 2.54, and 8.89%, respectively (p = .015). Ischemic stroke rates were 0.00, 3.67, and 5.56%, respectively (p = .031). By multivariate analysis, the RSS was an independent predictor of 2-year MACE (hazard ratio: 2.09, 95% CI: 1.36-3.21, p = .001). Receiver-operator characteristic analysis indicated that the area under the curve significantly improved from 0.63 to 0.69, when RHI was added to SS (p < .0001). CONCLUSIONS: RSS is correlated with 2-year MACE in patients presenting with ACS undergoing PCI.