Enoxaparin versus unfractionated heparin with fibrinolysis for ST-elevation myocardial infarction.
BACKGROUND
Unfractionated heparin is often used as adjunctive therapy with fibrinolysis in patients with ST-elevation myocardial infarction. We compared a low-molecular-weight heparin, enoxaparin, with unfractionated heparin for this purpose.


METHODS
We randomly assigned 20,506 patients with ST-elevation myocardial infarction who were scheduled to undergo fibrinolysis to receive enoxaparin throughout the index hospitalization or weight-based unfractionated heparin for at least 48 hours. The primary efficacy end point was death or nonfatal recurrent myocardial infarction through 30 days.


RESULTS
The primary end point occurred in 12.0 percent of patients in the unfractionated heparin group and 9.9 percent of those in the enoxaparin group (17 percent reduction in relative risk, P<0.001). Nonfatal reinfarction occurred in 4.5 percent of the patients receiving unfractionated heparin and 3.0 percent of those receiving enoxaparin (33 percent reduction in relative risk, P<0.001); 7.5 percent of patients given unfractionated heparin died, as did 6.9 percent of those given enoxaparin (P=0.11). The composite of death, nonfatal reinfarction, or urgent revascularization occurred in 14.5 percent of patients given unfractionated heparin and 11.7 percent of those given enoxaparin (P<0.001); major bleeding occurred in 1.4 percent and 2.1 percent, respectively (P<0.001). The composite of death, nonfatal reinfarction, or nonfatal intracranial hemorrhage (a measure of net clinical benefit) occurred in 12.2 percent of patients given unfractionated heparin and 10.1 percent of those given enoxaparin (P<0.001).


CONCLUSIONS
In patients receiving fibrinolysis for ST-elevation myocardial infarction, treatment with enoxaparin throughout the index hospitalization is superior to treatment with unfractionated heparin for 48 hours but is associated with an increase in major bleeding episodes. These findings should be interpreted in the context of net clinical benefit. (ClinicalTrials.gov number, NCT00077792.).
Thrombolysis in Myocardial Infarction (TIMI) Study Group, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. eantman@rics.bwh.harvard.edu
Elliott M
EM
Antman
David A
DA
Morrow
Carolyn H
CH
McCabe
Sabina A
SA
Murphy
Mikhail
M
Ruda
Zygmunt
Z
Sadowski
Andrzej
A
Budaj
Jose L
JL
López-Sendón
Sema
S
Guneri
Frank
F
Jiang
Harvey D
HD
White
Keith A A
KA
Fox
Eugene
E
Braunwald
D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D017984:Enoxaparin / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006470:Hemorrhage / Q000139:chemically induced; D006493:Heparin / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D020300:Intracranial Hemorrhages / Q000139:chemically induced; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000401:mortality; D012008:Recurrence; D012306:Risk; D016896:Treatment Outcome
D000925:Anticoagulants; D017984:Enoxaparin; D005343:Fibrinolytic Agents; D006493:Heparin