Predictors of thrombus burden and no-reflow of infarct-related artery in patients with ST-segment elevation myocardial infarction: importance of platelet indices.

Preprocedural high-thrombus burden (HTB) of infarct-related artery (IRA) is a harbinger of procedural complications following primary percutaneous coronary intervention (PCI) in patients with ST-elevation myocardial infarction (STEMI). The HTB of IRA can lead to poor outcomes by various mechanisms, including no-reflow phenomenon, increased myocardial necrosis and with subsequent reduced survival benefit at follow-up. In this study, we investigated the relationship between all platelet indices on admission and thrombus burden and the no-reflow phenomenon after primary PCI of IRA in patients with STEMI. We retrospectively enrolled 475 patients with STEMI undergoing primary PCI. Study population was divided into two groups according to the thrombolysis in myocardial infarction thrombus grade of IRA as low-thrombus burden or HTB. There were no statistically significant differences in platelet indices, including platelet count, platelet-large cell ratio (P-LCR), mean platelet volume (MPV) and platelet distribution with (PDW) among the groups. However, in the subgroup analysis, P-LCR, MPV and PDW were significantly higher in the no-reflow patients than reflow patients despite similar platelet count (P for all < 0.001). The cutoff value of P-LCR for predicting no-reflow was 26.5% with a sensitivity of 67.0% and a specificity of 62% (area under the curve, 0.689; 95% confidence interval, 0.614-0.765; P < 0.001). Furthermore, P-LCR, MPV and PDW had similar AUC (0.689, P < 0.001; 0.688, P < 0.001; and 0.677, P < 0.001; respectively) for predicting no-reflow phenomenon after primary PCI. As a result, all of the platelet indices have no effect on thrombus load of IRA, however, these parameters seem to impair epicardial perfusion after primary PCI.