Unfractionated heparin–clopidogrel combination in ST-elevation myocardial infarction not receiving reperfusion therapy

Objective: We sought explore the relative benefits of unfractionated heparin (UFH) compared with enoxaparin, alone or in combination with clopidogrel, in ST-segment elevation myocardial infarction (STEMI) patients not undergoing reperfusion therapy. Methods: This is a propensity score study from The International Survey on Acute Coronary Syndromes in Transition Countries (ISACS-TC/NCT01218776) on patients admitted between October 2010-June 2013. There were a total of 1175 STEMI patients who did not receive mechanical or pharmacological reperfusion. Of these, 1063 were eligible for the aim of the study, being treated with UFH (522/1175;44.4%) or enoxaparin (541/1175;46%). Clopidogrel in combination with UFH or enoxaparin was given to 751 (63.9%) patients. The primary endpoint was in-hospital mortality. Secondary endpoints were intracranial hemorrhages, and clinically relevant bleedings. Results: After adjustment for any confounders, UFH was associated with a lower risk of in-hospital mortality in clopidogrel users (multivariate adjusted regression analysis: odds ratio [OR]:0.62, 95%Confidence Interval [CI] 0.41-0.94) as compared with clopidogrel non-users (OR: 0.94, 95%CI 0.55-1.60). The observed effect was not associated with combined enoxaparin and clopidogrel therapy. Major bleeding events were comparable in the enoxaparin group and UFH group (0.4% and 1.5% respectively, p=0.06). The risk of major hemorrhage was nearly similar with combined UFH-clopidogrel therapy (1.4%) as compared with UFH alone (1.9%), p=0.67. Conclusion: UFH - Clopidogrel combination was associated with a large mortality reduction in STEMI patients not undergoing reperfusion therapy and did not significantly increase the risk of major bleeding.