SAN FRANCISCO, CA—The combination of unfractionated heparin (UFH) and clopidogrel was associated with a reduced risk of in-hospital morality, with benefits consistent across all age groups, a study presented at ACC.13, the American College of Cardiology’s 62nd Annual Scientific Session has found.

“Clinical decision about whether to offer new anticoagulant agents or UFH therapy to patients who fail to receive any reperfusion therapy is still a matter of uncertainty,” said Professor Edina Cenko, of the Department of Experimental, Diagnostics and Specialized Medicine, Section of Cardiology, University of Bologna, Bologna, Italy, and colleagues.

Approximately 33% of patients with ST-segment elevation myocardial infarction (STEMI) do not receive reperfusion therapy. To investigate the relative benefits of enoxaparin vs. UFH in association with clopidogrel in STEMI patients not undergoing reperfusion, the investigators used the dataset of the International Survey of Acute Coronary Syndromes in Transitional Countries (ISACS-TC) to review current practice.

Of the 1,440 consecutive patients with STEMI enrolled from 2007–2011, 584 (40.6%) did not receive reperfusion therapy. At admission, 223 patients were treated with enoxaparin and 292 patients with UFH. All patients received aspirin and/or clopidogrel.

Significant interaction between UFH and clopidogrel (P<0.001) was observed; therefore, they performed a separate analysis for clopidogrel users and non-users. Use of UFH was associated with a lower risk of in-hospital death in clopidogrel users; adjusted OR 0.38 (0.20–0.71; P=0.002) and propensity risk score adjusted OR 0.42 [0.23-0.77].

“The effect of UFH was favorable only in concomitant treatment with clopidogrel,” they noted. The mortality rate was not statistically significant for unfractionated heparin alone, enoxaparin alone, or enoxaparin plus clopidogrel.

“Observational studies do not control for unmeasured differences in patient characteristics,” Prof. Cenko stated. “Propensity analyses reduce the bias to an acceptable level.”