The Prognostic Value of ADP-Induced Platelet Aggregation for Bleeding Complications in Low - Intermediate Risk Patients with Acute Coronary Syndrome Taking Clopidogrel After Percutaneous Coronary Intervention.

BACKGROUND: Platelet aggregation may predict the bleeding outcomes after percutaneous coronary intervention (PCI). METHODS: Consecutive patients with non-high risk acute coronary syndrome and indication for PCI were enrolled. Maximum adenosine diphosphate-induced platelet aggregation (ADP-PGmax) was assessed by light transmission aggregometry. Study endpoints were the incidence of haemorrhage, categorised by Thrombolysis in Myocardial Infarction criteria, and significant entry-site complications during hospitalisation and six-month follow-up period. Platelet aggregation test was organised at 24h after PCI and 1 month after discharge respectively. The optimal platelet aggregation was detected defining enhanced clopidogrel response, and associations of measurements with endpoints were assessed. RESULTS: A total of 278 patients were included in analyses. Study endpoints were observed in 24 (8.6%) patients [major bleeding, n=4 (1.4%); minor bleeding, n=11 (4.0%); significant entry-site complication, n=9 (3.2%)]. In multivariate analysis, follow-up ADP-PGmax[odds ratio (OR)=0.96;95% confidence interval (CI),0.93-0.99;p=0.008) and renal insufficiency (OR=3.29; 95%CI, 1.23-8.85; p=0.018) were predictors of bleeding events. The optimal cutoff value for follow-up ADP-PGmax was 24.5% (area under the curve=0.72; 95% CI, 0.59-0.85; p<0.001). Bleeding occurred in 26.2% (16/61) of patients with enhanced clopidogrel response and 3.7% (8/217) of other patients (OR=9.26; p<0.001). CONCLUSION: Enhanced clopidogrel responsiveness was associated with an increased risk of bleeding and entry-site complication. Platelet function testing at an appropriate time after clopidogrel administration helps to identify patients at high risk of bleeding.