ObjectivesThis study sought to assess the impact of residual coronary artery disease (CAD), using the residual SYNTAX score (rSS), on in-hospital outcomes after primary percutaneous intervention (PPCI). The study also aimed to determine independent predictors for high rSS. Residual CAD has been associated with worsened prognosis in patients undergoing PCI for non-ST acute coronary syndromes. The rSS is a systematic angiographic score that measures the extent and complexity of residual CAD after PCI. Materials and MethodsData from 243 consecutive patients undergoing PPCI for ST-elevation myocardial infarction (STEMI) were analyzed. The rSS was derived from post-PPCI angiography. Patients were dichotomized into low (<8) and high rSS (8) groups and outcomes were compared between groups. The primary outcome of net adverse cardiovascular events (NACE) consisted of a composite of in-hospital death, congestive heart failure (CHF), recurrent MI and bleeding. ResultsThe mean rSS was 4.7 (7.2). A high rSS was associated with the primary outcome (P<0.0001), in-hospital death (P=0.0026), periprocedural death (P<0.0001), CHF (P<0.0004) and acute kidney injury (P<0.0019). A high rSS was also an independent predictor of the primary outcome with an OR of 3.82. Independent predictors of a high rSS included a history of diabetes (OR 2.8), previous MI (OR 5.75), 2-vessel disease (VD) (OR 15.48, vs. 1-VD) and 3-VD (OR 57.06, vs. 1-VD). ConclusionsResidual CAD, as assessed by the rSS, confers a worsened prognosis in patients undergoing PPCI. Diabetes, previous MI and multi-vessel disease were independent predictors of a high rSS. (c) 2016 Wiley Periodicals, Inc.