Intravenous low-molecular-weight heparins compared with unfractionated heparin in percutaneous coronary intervention: quantitative review of randomized trials.

BACKGROUND: Despite its limitations, unfractionated heparin (UFH) is the recommended anticoagulant during percutaneous coronary intervention (PCI). Few randomized trials have compared low-molecular-weight heparin (LMWH) and UFH, and most lacked the power to detect a difference between the 2 anticoagulants in terms of safety or efficacy. Our objective was to perform a meta-analysis of randomized trials comparing the efficacy and safety of LMWH vs UFH as anticoagulants in the setting of PCI. METHODS: We used MEDLINE, randomized trials presented at major cardiology conferences, and journal article bibliographies from January 1998 and September 2006. Two reviewers independently identified randomized studies comparing the intravenous administration of LMWH vs UFH among patients undergoing PCI. Data on sample size, baseline characteristics, and outcomes of interest were independently extracted and analyzed. RESULTS: Thirteen trials including 7318 patients met the inclusion criteria. A total of 4201 patients (57.4%) received LMWH, and 3117 patients (42.6%) received UFH. Intravenous LMWH use was associated with a significant reduction in the risk of major bleeding compared with UFH (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.40-0.82; P = .002). A trend toward a reduction in minor bleeding was also observed among LMWH-treated patients (OR, 0.75; 95% CI, 0.47-1.20; P = .24). Similar efficacy was observed between LMWH and UFH regarding the double end point of death or myocardial infarction (OR, 0.99; 95% CI, 0.79-1.24; P = .93). There were no significant differences in death, myocardial infarction, and urgent revascularization between patients receiving LMWH and those receiving UFH. CONCLUSION: The use of intravenous LMWH during PCI is associated with a significant reduction in major bleeding events compared with UFH, without compromising outcomes on hard ischemic end points.