Thrombolysis and the general practitioner. 1. Practicable only under certain circumstances.

If thrombolytic treatment represents the second major advance in the management of patients with acute coronary thrombosis, will it gain more widespread acceptance in prehospital treatment than the other major advance, defibrillation? For more than 20 years it has been clear that almost half of the early deaths from myocardial infarction occur within the first two hours, and yet we have failed to provide a mechanism by which early ventricular defibrillation may be achieved. The advent of thrombolytic treatment may provide the necessary impetus for major revision of the prehospital management of acute coronary occlusion. Should family practitioners give thrombolytic agents in a patient's home? The key underlying questions are whether such treatment confers benefit, whether it could be achieved promptly-that is, within the first hour-and whether the advantages outweigh the potential hazards. Benefits of thrombolytic treatment The evidence to support the use of thrombolytic treatment is now overwhelming,` and the benefits of thrombolysis diminish as the time delay lengthens after the onset of symptoms.'' For example, in the GISSI study streptokinase treatment within the first three hours was associated with the greatest improvement in mortality (12 0% controls, 9-2% streptokinase), and a subset analysis of patients treated within the first hour showed a dramatic reduction in mortality of about 47% (15 4% controls, 8 2% streptokinase).' A similar relation with time was shown in the second international study of infarct survival (ISIS-2): treatment within the first hour resulted in 13-4% mortality with placebo and 8 1% with streptokinase treatment.' The odds of death were further reduced by the addition of aspirin, but the temporal relations were less pronounced with aspirin. Even in a study of this size (17 187 patients) the numbers of deaths after early treatment were relatively small and hence the confidence intervals do not allow firm conclusions to be drawn with respect to treatment within the first hour. Nevertheless, in view of substantial experimental evidence, injury will be minimised and recanalisation more common with early thrombolysis./"' Further clinical studies of very early treatment are required, but according to current evidence delay in treatment increases myocardial injury and the risks of death, and hence rational policies must aim at minimising the delay. Advantages versus hazards of treatment Can delays be minimised by general practitioners giving the thrombolytic agent in a patient's home? Studies in Britain9'-and elsewhere'12-4 show that patients receive treatment in hospital more rapidly after direct …