Persistent platelet activation is related to very early cardiovascular events in patients with acute coronary syndromes.

INTRODUCTION Persistent platelet function while on antiplatelet therapy affects outcomes in patients with acute coronary syndromes (ACS). AIM To evaluate whether platelet reactivity measured by collagen-epinephrine (CEPI) or collagen-ADP (CADP) closure times (CT) with Platelet Function Analyzer 100 (PFA-100) is related to very early, in-hospital cardiovascular events in patients with ACS. METHODS The study included 91 patients with ACS undergoing percutaneous coronary intervention (PCI) with stent implantation who were treated with aspirin and clopidogrel. Patients were stratified in accordance with both CEPI-CT (<190 s or >190 s), reflecting aspirin resistance, and our own cut-off point for CADP-CT measured at a mean of 6 days after admission. In-hospital events included re-infarction, cardiac arrest, recurrent angina, severe arrythmias, pulmonary oedema and cardiogenic shock. RESULTS Patients were divided into 4 study groups: group 1 with CADP-CT <104 s (n=10, 11.0%), group 2 with CEPI-CT <190 s (n=10, 11.0%), group 3 with CADP-CT <104 s and CEPI-CT <190 s (n=9, 9.9%) and a control group with both CT values above the cut-off limits (n=62, 68.1%). The baseline clinical characteristics and received treatment of each subgroup were similar. A test for a trend between controls, group 1 or 2 and group 3 disclosed statistical significance (p <0.001). When analysed separately, only patients from group 3 had a higher incidence of negative outcomes compared to controls (p <0.005; relative risk RR - 9.0; 95% CI 2.4-33.9). CONCLUSIONS Enhanced platelet function after PCI when measured under high shear rates by both PFA-100 cartridges is independently associated with the most unfavourable in-hospital clinical outcome.