Comparison of low molecular weight heparin with unfractionated heparin during percutaneous coronary interventions: a meta-analysis.

To conduct a meta-analysis of the current evidence to evaluate the safety and efficacy of low molecular weight heparin (LMWH) as compared to unfractionated heparin (UFH). Several studies have demonstrated the therapeutic advantage of LMWH over UFH in the medical management of acute coronary syndromes. However, evidence comparing the 2 in percutaneous coronary interventions (PCI) is inconclusive. Previously published meta-analysis did not include some large-scale trials. We performed a systematic literature search for randomized clinical trials that compared LMWH and UFH in urgent or elective PCI. Studies that evaluated efficacy end points [composite of nonfatal myocardial infarction (MI) and death with or without target vessel revascularization] and bleeding end points were included. Studies were excluded if they involved coadministration of thrombolytics. Data were extracted on an intention-to-treat basis. Heterogeneity of the studies was analyzed by Cochran Q statistics. The Mantel-Haenszel fixed-effect model was used to calculate combined relative risks for outcomes where studies were homogenous and the random effect model when the studies were heterogenic. Fourteen studies involving 12,394 patients were included. The efficacy and bleeding risk of LMWH in patients undergoing PCI were comparable with UFH. A subgroup analysis of studies using intravenous or intraarterial administration of LMWH, demonstrated them to be safer than UFH with comparable efficacy. LMWH is at least as efficacious and safe as UFH in patients undergoing PCI. Additionally, evidence suggests that LMWH, when used intravenously, is associated with lower bleeding risks when compared with UFH.