Background: Low-molecular-weight heparin (LMWH) offers pharmacological and practical advantages over unfractionated heparin (UFH). Whether these advantages translate into greater infarct-related artery patency and fewer adverse clinical events in patients with ST-elevation myocardial infarction (STEMI) receiving fibrinolytic therapy remains under study.
Methods and results: We compared angiographic and clinical outcomes in patients treated with LMWH (n=1429) versus UFH (n=1431) in CLARITY-TIMI 28, a randomized trial of clopidogrel versus placebo in STEMI patients aged 18 to 75 years undergoing fibrinolysis. After comprehensive adjustment for baseline characteristics, therapeutic interventions, and a propensity score, treatment with LMWH was associated with a significantly lower rate of a closed infarct-related artery or death or myocardial infarction before angiography (13.5% versus 22.5%, adjusted OR 0.76, P=0.027). Treatment with LMWH was also associated with a significantly lower rate of cardiovascular death or recurrent myocardial infarction through 30 days (6.9% versus 11.5%, adjusted OR 0.68, P=0.030). The lower event rates were observed in patients allocated to clopidogrel and in those who underwent percutaneous coronary intervention. Rates of TIMI major bleeding through 30 days (1.6% versus 2.2%, P=0.27) and intracranial hemorrhage (0.6% versus 0.8%, P=0.37) were similar in the LMWH and UFH groups. Patients who received both clopidogrel and LMWH, in addition to a standard fibrinolytic and aspirin, had a particularly high rate of infarct-related artery patency (90.9%) and particularly low rates of cardiovascular death (3.2%), recurrent myocardial infarction (3.0%), and major bleeding (1.8%).
Conclusions: In patients with STEMI receiving fibrinolytic therapy, use of LMWH with other standard therapies, including clopidogrel and aspirin, is associated with improved angiographic outcomes and lower rates of major adverse cardiovascular events.