Randomized clinical trial of urokinase versus heparin in unstable angina

The aim of this study was to evaluate the clinical effect of urokinase (UK) in unstable angina (UA). This study was a multicenter, single-blind, heparin-controlled, randomized clinical trial. Entry criteria was that effort angina was significantly aggravated within 96 hours and angina attack at rest within 24 hours. In addition to the control group, thrombolytic therapy was divided into two groups according to the dose of UK. The high-dose group was 18,000 IU/kg, and the total dose was no more than 1.5 million IU (no bolus of heparin in this dose). The low-dose group was 14,000 IU/kg, and the total dose was no more than 1 million IU. All patients were treated by aspirin 300 mg/day and heparin 3000 U IV bolus before thrombolytic therapy (except for the high-dose group), then subcutaneous heparin 7,500 U q12h. The primary endpoint for the comparison between the thrombolytic and control groups was death and AMI (cardiac event) within 30 days of enrollment. Five hundred and fifty-six patients with UA were selected, and 272 and 284 patients were enrolled in thrombolytic group and control groups, respectively. The 30-day incidence of cardiac events was a little higher, but not significantly, in the thrombolytic group than in the control group (7.0% vs. 5.3%, ns), but the rate for cardiac events was much lower in the low-dose UK group than in the high-dose UK group. The difference was significant (3.3% vs. 10.0%, P < 0.05). Even if the rate was also lower than in the control group, this difference was not significant (3.3% vs. 5.3%, P > 0.05). The time interval between enrollment and the AMIs was quite different in these two groups. The majority of AMIs (73.7%) occurred within 24 hours, including 37% of AMIs that occurred within 2 hours after the beginning of thrombolytic therapy in the UK group. However, only small number of AMIs (20%) occurred within 24 hours of enrollment in the control group. The increase in AMI risk on the first day of thrombolytic therapy in this study might be closely related to thrombolysis and to the lack of strong antithrombin therapy. The risk of AMI might be remarkably reduced by using low-dose UK in combination with antithrombin therapy before thrombolytic therapy.