Hirudin in acute myocardial infarction. Thrombolysis and Thrombin Inhibition in Myocardial Infarction (TIMI) 9B trial.

BACKGROUND

The TIMI 9 trial evaluated whether the direct antithrombin hirudin is more effective than an indirect-acting antithrombin, heparin, as adjunctive therapy for thrombolysis in myocardial infarction.

METHODS AND RESULTS

Patients (n = 3002) with acute myocardial infarction were treated with aspirin and either accelerated-dose tissue plasminogen activator (TPA) or streptokinase. They were randomized within 12 hours of symptoms to receive either intravenous heparin (5000 U bolus followed by infusion of 1000 U/h) or hirudin (0.1 mg/kg bolus followed by infusion of 0.1 mg/ kg per hour). The infusions of both antithrombins were titrated to a target activated partial thromboplastin time (aPTT) of 55 to 85 seconds and were administered for 96 hours. Patients randomized to hirudin were significantly more likely to have an aPTT measurement in the target range (P < .0001). The primary end point (death, recurrent nonfatal myocardial infarction, or development of severe congestive heart failure or cardiogenic shock by 30 days) occurred in 11.9% of the 1491 patients in the heparin group and 12.9% of the 1511 patients in the hirudin group (P = NS). Subgroup analyses did not reveal any profile of patients who benefited more from one of the antithrombins. The rate of major hemorrhage was similar in the heparin (5.3%) and hirudin (4.6%) groups; intracranial hemorrhage occurred in 0.9% of the heparin and 0.4% of the hirudin patients.

CONCLUSIONS

Heparin and hirudin have an equal effect as adjunctive therapy to TPA and streptokinase in preventing unsatisfactory outcome in patients with acute myocardial infarction. Similar rates of major bleeding were observed for patients in the heparin and hirudin groups.