Myocardial infarction: is evidence-based medicine the best?

Success of resuscitation was defined as survival for 30 days1 or to discharge from hospital2 after a first cardiac arrest, and there had to be documentation of the arrest rhythm, which was nearly always ventricular fibrillation. Each such survivor was regarded as a life saved. Survival due to fibrinolytic treatment was estimated with figures from two meta-analyses3,4 that respectively derived an average figure of 30 lives saved per 1000 patients treated3 or a time-dependent salvage of 65 per 1000 for patients treated within the first hour of onset, and 37 per 1000 (95% CI 20-55), 26 per 1000 (14-37), 29 per 1000 (19-40), 18 per 1000 (7-29), and 9 per 1000 (-5 to 22) for those treated 1-2 h, 2-3 h, 3-6 h, 6-12 h, and 12-24 h after onset, respectively.4 Delays to administration were known in both the UKHAS and SHARP studies, and survival was estimated with values from both meta-- analyses. However, results were practically identical, and reported figures were estimated according to the time-- dependent analysis in UKHAS and the average figure in SHARP. Results are summarised in the table. Overall, in the 3972 patients receiving medical care, resuscitation was successful in 257 (6.5%) and fibrinolysis prevented death in 63 (1.6%). In both studies, about 80% of the lives saved were attributable to resuscitation from cardiac arrest and about 20% to fibrinolytic treatment. Of the patients whose lives were saved by resuscitation, 36% and 39%, respectively, had had their first arrest outside hospital and so owed their lives primarily to the ambulance service. These results show the superiority of resuscitation from cardiac arrest over fibrinolytic treatment in terms of lives saved, at least for the first 1-4 weeks after the onset of myocardial infarction.