Enoxaparin is superior to unfractionated heparin in patients with ST elevation myocardial infarction undergoing fibrinolysis regardless of the choice of lytic: an ExTRACT-TIMI 25 analysis

Aims We compared outcomes of ST-elevation myocardial infarction (STEMI) patients randomized to a strategy of either enoxaparin or unfractionated heparin (UFH) to support fibrinolysis. Methods and results In the Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment-Thrombolysis in Myocardial Infarction Study 25 (ExTRACT-TIMI 25) trial, 20 479 patients undergoing fibrinolysis for STEMI with a fibrin-specific agent (N = 16 283) or streptokinase (SK) IN = 4139) were randomized to enoxaparin throughout their hospitalization or UFH for at [east 48 h. The primary end point of death or nonfatal recurrent MI through 30 days occurred in 12.0% of patients in the UFH and 9.8% in the enoxaparin groups when treated with fibrin-specific lytics [odds ratio(adjusted) (ORadj) 0.78; 95% Cl 0.70-0.87; P < 0.001] and 11.8 vs. 10.2%, respectively, when treated with SK (ORadj 0.83; 95% CI 0.66-1.04; P = 0-10; P-interaction = 0.58). Major bleeding rates including intracranial hemorrhage within the fibrin specific cohort were 1.2 and 2.0% in the UFH and enoxaparin groups, respectively (P < 0.001) and 2.0% in UFH and 2.4% in enoxaparin patients in the SK cohort (P = 0.16). Interaction tests between antithrombin- and lytic-type were non-significant (P = 0.20). Death, nonfatal MI, or major bleeding was significantly reduced with enoxaparin in the fibrin-specific cohort (ORadj 0.82; 95% Cl 0.74-0.91; P < 0.001) and favoured enoxaparin in the SK cohort (ORadj 0.89; 95% Cl 0.72-1.10; P = 0.29; P-interaction = 0.53). Conclusion The benefits of an enoxaparin strategy over UFH were observed in both SK and fibrin -specific-treated STEMI patients. Therefore, an enoxaparin strategy is preferred over UFH to support fibrinolysis for STEMI regardless of lytic agent.