PROLONGED STREPTOKINASE INFUSION IN PATIENTS WITH UNSTABLE ANGINA - RESULTS OF A RANDOMIZED, PLACEBO-CONTROLLED CLINICAL-TRIAL

Background The purpose of this study was to assess the efficacy both o f prolonged (48 h) and of short-duration (1 h) administrations of stre ptokinase in patients with unstable angina. In unstable angina, thromb osis is a dynamic process that waxes and wanes for hours and even days . The majority of previous studies have investigated the efficacy of s hort-duration thrombolytic regimens. Methods One hundred patients with acute unstable angina were randomly allocated to receive placebo, 1 5 00 000 U streptokinase during 1 h or 250 000 U streptokinase during 1 h and then a prolonged infusion of 100 000 U for the next 48 h. All of the treatments included intravenous heparin administration for 72 h.R esults No death occurred in the study population, One of 34 patients t reated with placebo (2.9%), three of 33 treated with streptokinase dur ing 1 h (9.0%) and three of 33 treated with streptokinase during 48 h (9.0%) had a myocardial infarction. Refractory angina occurred in nine , three and seven patients receiving placebo, streptokinase during 1 h and streptokinase during 48 h, respectively. Kaplan-Meier analysis sh owed that the total probability for a patient to be free of cumulative events did not differ among the three groups of patients (NS). Fourte en patients (41%) receiving placebo, 15 patients (45%) receiving strep tokinase during 1 h and 14 patients (42%) receiving streptokinase duri ng 48 h had ischaemic episodes detected by Holter monitoring during th e first 72 h after hospital admission (NS). Two patients receiving str eptokinase during 48 h required blood transfusion, and a greater incid ence of minor bleeding (P <0.05) and adverse events (P <0.02) was obse rved in patients receiving prolonged streptokinase administration than in those receiving streptokinase during 1 h or placebo. Conclusions I n patients with acute unstable angina, the administration of two diffe rent regimens of streptokinase significantly reduces the probability n either of developing cardiac events during hospitalization nor of isch aemia detected by Holter monitoring in the early phase after hospital admission. Although the sample size of the study provided sufficient p ower to exclude only a large difference in effect size, it did allow u s to detect a significantly higher incidence of bleeding in the group of patients treated with prolonged streptokinase infusion.