Abstract 4013: Heparin Therapy During Fibrinolysis in ST-Segment Elevation Myocardial Infarction: Registry Data Support Clinical Trial Results
Background Antithrombotic therapy in patients with acute ST-segment elevation myo-cardial infarction (STEMI) given fibrinolysis (lytic) is intended to improve outcomes. The clinical benefit of the low-molecular-weight heparin (LMWH) enoxaparin vs unfractionated heparin (UFH) was confirmed recently in the EXTRACT randomized clinical trial. Observational studies of unselected populations may provide complementary information to that from clinical trials.
Hypothesis In the ‘real-world’ setting, adjunctive therapy with LMWH is associated with lower outcomes vs UFH in STEMI patients treated with lytics.
Methods This analysis is based on 2515 patients with STEMI enrolled in the Global Registry of Acute Coronary Events between April 1999 and March 2005. All patients received a lytic within 6 hours of symptom onset (none had major contraindications to lytic therapy). The rates of hospital major bleeding (using the GRACE criteria) and 30-day death or recurrent myocardial infarction (MI) were analyzed. Data from 738 patients who received both UFH and LMWH were excluded from the analysis.
Results The rates of death were similar in both groups. The rates of MI or death/MI were lower in patients who received LMWH compared with those given UFH. Following multivariable analysis adjusting for the GRACE risk score and treatment type (LMWH, UFH), use of LMWH was associated with a lower incidence of death/MI (hazard ratio 0.54, 95% CI 0.39 – 0.75) when compared to no heparin. The incidence of hospital bleeding was similar in the two groups.
Conclusions The combined endpoint of death and MI in this multinational observational study of unselected patients was higher than that in the EXTRACT trial (12% with UFH vs 9.9% with enoxaparin). STEMI patients who received lytic therapy and were treated with LMWH had better outcomes than those given UFH.