Clinical significance of thrombocytopenia during a non-ST-elevation acute coronary syndrome - The platelet glycoprotein IIb IIIa in unstable angina: Receptor suppression using integrilin therapy (PURSUIT) trial experience

Background-The significance of thrombocytopenia in patients experiencing an acute coronary syndrome (ACS) has not been examined systematically. We eva luated this condition in a large non-ST-elevation ACS clinical trial, with particular interest paid to its correlation with clinical outcomes. Methods and Results-Patients presenting without persistent ST elevation dur ing an ACS were randomized to receive a double-blind infusion of the platel et glycoprotein (GP) IIb/IIIa inhibitor eptifibatide or placebo in addition to other standard therapies including heparin and aspirin. The primary end point was death/nonfatal myocardial infarction (MI) at 30 days, whereas bl eeding and stroke were the main safety outcomes. Thrombocytopenia (nadir pl atelet count <100 x 10(9)/L or <50% of baseline) occurred in 7.0% of enroll ed patients. The time to onset was a median of 4 days in both treatment arm s. Patients with thrombocytopenia were older, weighed less, were more likel y nonwhite, and had more cardiac risk factors. These patients experienced s ignificantly more bleeding events: they were more than twice as likely to e xperience moderate/severe bleeding after adjustment for confounders. Univar iably, ischemic events (stroke, MI, and death) occurred significantly (P<0. 001) more frequently in patients with thrombocytopenia; multivariable regre ssion modeling preserved this association with death/nonfatal MI at 30 days . Neither the use of heparin or eptifibatide was found to independently inc rease thrombocytopenic risk, Conclusions-Although causality between thrombocytopenia and adverse clinica l events could not be established definitively, thrombocytopenia was highly correlated with both bleeding and ischemic events, and the presence of thi s condition identified a more-at-risk patient population.