Ten-year follow-up of the first megatrial testing thrombolytic therapy in patients with acute myocardial infarction: results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto-1 study. The GISSI Investigators.

Background: We conducted a 10-year follow-up of the 11 712 patients with acute myocardial infarction randomized in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto-1 study, the first large trial assessing thrombolytic therapy.
Methods and Results: Information on survival at 10 years was obtained for the 93% of all randomized patients through the census offices of their towns of residence. The difference in survival produced by streptokinase and sustained up to 1 year was still significant at 10 years (log-rank test, P=0.02), with the absolute benefit of 19 (95% CI 1 to 37) lives saved per 1000 patients treated. The time dependence of the extent of the benefit was confirmed, as the higher mortality rate reductions found in patients treated earlier were still present at 10 years. In the overall population, most of the benefit was obtained before hospital discharge (RR 0.81, 95% CI 0.72 to 0.90), since no difference in survival between thrombolyzed and control patients discharged alive was found at 10 years (RR 0.98, 95% CI 0.90 to 1.06). However, a slight albeit nonsignificant divergence of the survival curves of patients randomized within the first hour was observed [90 (95% CI 34 to 146) lives saved per 1000 at 10 years versus 72 (95% CI 37 to 107) lives saved at hospital discharge].
Conclusions: The benefits of a single intravenous infusion of 1.5 million units of streptokinase in prolonging survival of patients with acute myocardial infarction is sustained up to 10 years, with a still-evident trend in favor of the patients admitted earlier.