Objectifying the impact of incomplete revascularization by repeat angiographic risk assessment with the residual SYNTAX score after left main coronary artery percutaneous coronary intervention

Objectives We investigated the prognostic accuracy of a standardized quantification of incomplete revascularization after percutaneous coronary intervention (PCI) of the unprotected left main coronary artery (ULMCA) named residual SYNTAX score (rSS). Background Prognostic implications of coronary lesions left untreated after ULMCA PCI are confounded by the lack of a uniform definition of incomplete revascularization. Methods Baseline SYNTAX score (bSS), rSS, and the difference between bSS and rSS (ΔSS) were assessed in predicting the risk of 2‐year cardiac mortality of 400 patients undergoing ULMCA PCI. Results The rSS and bSS showed comparable discrimination (rSS area under the curve [AUC] 0.72, 95% confidence interval [95% CI] 0.61–0.83; bSS AUC 0.73, 95% CI 0.62–0.84). Hosmer–Lemeshow statistics were 0.60 for rSS (P = 0.44) and 2.45 (P = 0.12) for bSS, reflecting better calibration ability of the rSS. The ΔSS provided the worst discrimination and calibration characteristics (AUC 0.55; 95% CI 0.44–0.66; Hosmer–Lemeshow statistic 3.13, P = 0.08). The rSS was independently associated with the 2‐year adjusted‐risk of cardiac mortality (hazard ratio 1.07, 95% CI 1.03–1.12, P = 0.001). The risk information from both the rSS and bSS slightly improved the discrimination ability compared with risk information from each single risk assessment (AUC 0.74, 95% CI 0.62–0.86) with a net reclassification improvement of +14.2% and +13.6% over rSS and bSS alone, respectively. Conclusions The rSS carries a prognostic value as independent predictor of 2‐year cardiac mortality. Compared with a single assessment of the SYNTAX score, information coming from repeat assessment of the angiographic risk may improve the ability to discriminate and reclassify patients undergoing ULMCA PCI. © 2013 Wiley Periodicals, Inc.