The change in platelet count in patients with acute coronary syndrome 6 months after coronary stent implantation.

After coronary stent implantation, patients with acute coronary syndrome commonly take clopidogrel, and few patients develop severe thrombocytopenia related to clopidogrel. However, we found in our clinical practice that platelet counts of most patients decrease slightly after taking clopidogrel for 6 months. To address this discrepancy, we studied the change in platelet count after coronary stent implantation in patients with acute coronary syndrome. Ninety-five patients were selected for this study, and their pre-stent platelet counts were compared with those 6 months after stent implantation. All patients had low/intermediate-risk non-ST segment elevation myocardial infarction/unstable angina and underwent delayed coronary interventional treatment. No patient suffered from thrombocytopenia (<100 × 10/l) during the 6-month observation period. Six months after stent implantation, platelet counts significantly decreased in the majority of patients (73/95, 76.9%) and increased only in the minority of patients (22/95, 23.1%). A multivariate analysis showed that the change in platelet count was positively correlated with the change in leukocyte and fibrinogen value, and negatively correlated with number of stents. The platelet count decreased in the majority of patients after stent implantation, which may be caused by the removal of stress factors or stent-related platelet consumption. Clopidogrel may partly prevent stent-related platelet consumption.