Accelerated streptokinase and enoxaparin in ST-segment elevation acute myocardial infarction (the ASENOX study)

Abstract

Background: The streptokinase (SK) regimen (1.5 MU/60 min) has remained unchanged in the ST-segment elevation acute myocardial infarction (STEMI) for the last 20 years.

Aim: To compare the efficacy of an accelerated SK (ASK) regimen combined with enoxaparin (Enox) or heparin (UFH) with the standard SK and UFH combination in STEMI.

Methods: 633 consecutive patients, aged 21-74 years, admitted within 6 hours after the onset of STEMI, were divided in three groups: (1) ASKEnox (n=165): Enox 40 mg. i.v. followed by SK 1.5 MU over 20 min, either as a full dose or a double infusion of 0.75 MU over 10 min. separated by 50 min. After SK infusion, Enox was administered 1 mg/kg s.c. every 12 hours for 5-7 days; (2) ASKUFH (n=264): the same ASK regimen plus UFH 1,000 IU/h for 48-72 hours, (3) SSKUFH (n=204): SK 1.5 MU/60 min. plus UFH 1,000 IU/h for 48-72 hours. All patients received aspirin. Three coronary reperfusion (CR) criteria were used: 1. rapid cessation of chest pain; 2. rapid reduction of ST-segment elevation by more than 50% of the initial value; 3. rapid increase in plasma CK and CK-MB with a peak in the first 12 hours.

Results: The rates of CR in the ASKEnox (77.6%) and the ASKUFH (73.5%) groups were similar but both were significantly higher than that observed in the SSKUFH group (62.2%) (p=0.002 and 0.013, respectively). The 30-day mortality rates were similar in the ASKEnox (6.06%) and the ASKUFH (6.81%) groups but both were significantly lower than in the SSKUFH group (12.74%) (p=0.048 and 0.044, respectively). SK-induced hypotension was more frequent in the ASKEnox (39.4%) and ASKUFH (38.3%) groups compared with the SSKUFH group (20.6%) (p<0.0001), but it was transient and well tolerated. Haemorrhagic stroke occurred in two patients from the SSKUFH and one patient from the ASKUFH groups.

Conclusions: ASKEnox and ASKUFH regimens are safe and result in a significantly higher rate of CR and a lower in-hospital mortality compared with the traditional SSKUFH regimen.