Adjunctive Low Molecular Weight Heparin During Fibrinolytic Therapy in Acute ST-Segment Elevation Myocardial Infarction: A Meta-Analysis Of Randomized Control Trials

Background: Recent data suggests that low molecular weight heparins (LMWHs) may be superior to unfractionated heparin (UFH) as an adjunct to fibrinolytic therapy in patients with acute ST-segment elevation myocardial infarction (STEMI). Hypothesis: We evaluated cardiac outcomes and the risk of major bleeding with LMWHs vs UFH in the management of STEMI. Methods: Seven randomized trials of patients with acute STEMI treated with fibrinolytic therapy and adjunctive LMWHs through the index hospitalization or weight-based UFH for at least 48 hours were identified. We analyzed both primary endpoints (death and nonfatal recurrent myocardial infarction through 30 days), and secondary endpoints (death, recurrent myocardial infarction, and major bleeding during index hospitalization at 7 days). Outcomes were computed using the Mantel-Haenszel fixed-effect model. A 2-sided alpha error of <0.05 was considered significant. Results: Compared to UFH, LMWH significantly reduced reinfarction (p<0.001) during hospitalization at 7 days and the effect remained consistent at 30 d (p<0.001). When analyzed for mortality at 7 days and 30 days follow-up, there were no statistically significant differences observed between the 2 groups. Additionally the LMWH group had higher risk of major bleeding (p<0.001). Conclusions: The present meta-analysis suggests in patients receiving fibrinolytic therapy for STEM[, LMWHs as an adjunctive therapy is superior to UFH in reducing reinfarction during hospitalization at 7 days and at 30 days. The mortality was not significant between the 2 groups during hospitalization at 7 days and at 30 days. However, UFH is superior to LMWHs in the reduction of major bleeding at 7 days index hospitalization.