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.