[Early prehospital thrombolysis in acute myocardial infarct: a moral obligation?]

Abstract

Acute myocardial infarction accounts for a large proportion of deaths from cardiovascular diseases. Occlusive thrombosis superimposed on a ruptured atheroma in an epicardial coronary artery is firmly established as the immediate cause of an acute myocardial infarction. Clinical research has focused on reducing the time to treatment, because necrosis of viable myocardial tissue mainly happens during the 30 to 90 min after coronary artery occlusion. Consequently, if the coronary artery can be reperfused during this period, extensive myocardial necrosis can be prevented and left ventricular function can be preserved. Indeed the mortality reduction by thrombolytic treatment compared with control is considerably higher in patients treated within 2 hours of symptom onset. Thrombolytic treatment during the first hour resulted in a 50% mortality reduction, which indicates 50 to 60 lives saved per 1000 patients treated. Early patency has crucial prognostic significance because the meta-analysis of all randomized trials of prehospital versus in-hospital thrombolysis shows that reducing treatment delay by 1 hour saves approximately 20 lives per 1000 patients treated. One way to reduce the delay is to bring the treatment to the patient in the prehospital setting. The safety and feasibility of prehospital thrombolysis strongly depend on the possibility of a rapid and correct diagnosis in the prehospital setting. To diagnose a myocardial infarction a standard 12-lead electrocardiogram is recorded and interpreted either on site by the emergency physician or, after telephone transmission, by a cardiologist on duty at the receiving coronary care unit. This approach has been proved to be safe. The most suitable prehospital thrombolytics are the third-generation agents given as a bolus, which have been tested in large hospital randomized control trials such as GUSTO-V and ASSENT III (reteplase and tenecteplase respectively), and the prehospital trial ASSENT III PLUS (tenecteplase). Hopefully future management of acute myocardial infarction with ST-segment elevation will include prehospital thrombolysis as a complementary part of any reperfusion strategy.