Residual platelet reactivity on aspirin therapy and recurrent cardiovascular events. A meta-analysis

Background: Recently, a growing body of evidence on the possible role of residual platelet reactivity (RPR) in affecting clinical events has accumulated. The aim of this study was to systematically assess the relationship between RPR on acetylic salicylic acid (ASA) therapy and the occurrence of recurrent events in a meta-analysis of prospective studies. Methods: A systematic literature search of MEDLINE, EMBASE, Science Citation Index, the Cochrane Systematic Review Database and bibliographies of retrieved articles through May 2007 was conducted. Studies were included if they analysed RPR in coronary heart disease patients in relation to the occurrence of adverse coronary events during follow-up. Results: Eleven prospective studies, incorporating 1952 patients with coronary heart disease followed for a time ranging from 6 days to 4 years, met the inclusion criteria. The pooled analysis demonstrated a significantly increased relative risk of adverse clinical events during follow-up for patients with RPR on ASA therapy (RR: 3.11, 95% CI 1.88-5.15; p < 0.0001). Moreover, the association between RPR and cardiovascular recurrences remained to be statistically significant even when subgroup analyses performed according to the duration of follow-up, ASA dosage, characteristics of the study population, and laboratory method were conducted. Conclusions: The present meta-analysis documents a significant association between RPR on ASA treatment and recurrent cardiovascular events. More prospective studies are needed to determine the independent prognostic importance of RPR during aspirin therapy and possible benefit of individually tailored anti-platelet treatment strategies in these patients.