Impaired coronary flow after primary percutaneous coronary intervention (PPCI) is associated with short- and long-term morbidity and mortality in patients with acute ST-segment elevation myocardial infarction (STEMI). Recent studies have demonstrated that platelet-to-lymphocyte ratio (PLR) is associated with adverse cardiovascular outcomes. The aim of this study was to assess the relation between admission PLR and angiographic reflow after PPCI. A total of 520 patients with acute STEMI (age 60 +/- 13 years; 74% men) occurring within 12 hours of the onset of symptoms who underwent PPCI were enrolled. The PLR and other laboratory parameters were measured before PPCI. The patients were divided into 2 groups based on the postintervention Thrombolysis in Myocardial Infarction (TIMI) flow grade: normal-reflow group (defined as postintervention TIMI grade 3 flow) and none-reflow group (consisted of both patients with angiographic no-reflow defined as postintervention TIMI grades 0 to 1 flow and slow flow defined as postintervention TIMI grade 2 flow). There were 117 patients (22.5%) in the none-reflow group (age 68 +/- 13 years and 77% men) and 403 patients in the normal-reflow group (age 58 +/- 12 years and 63% men). The none-reflow group had significantly higher PLR compared with the normal-reflow group (219 79 vs 115 +/- 59, p <0.001). In logistic regression analysis, PLR (odds ratio 1.818, 95% confidence interval 1.713 to 1.980, p <0.001) and total stent length (OR 1.052, confidence interval 1.019 to 1.086, p = 0.002) were independent predictors of none-reflow after PPCI. In conclusion, preintervention PLR is a strong and independent predictor of slow flow/no-reflow after PPCI in patients with acute STEMI. (C) 2014 Elsevier Inc. All rights reserved.