Six-month survival in 20,891 patients with acute myocardial infarction randomized between alteplase and streptokinase with or without heparin. GISSI-2 and International Study Group. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto.

This 6-month follow-up of the patients recruited into the GISSI-2 Study and the International Study substantially confirmed the in-hospital results. The aim was to compare the effectiveness and safety of alteplase (tPA) and streptokinase (SK), and of heparin and no heparin, in patients with acute myocardial infarction in an open multicentre randomized trial with a 2 x 2 factorial study design. Six-months' mortality rates were similar for patients randomized to tPA or SK (12.3% vs 11.7%, RR = 1.06, 95% CI 0.97-1.15) and for patients randomized to heparin or no heparin (11.9% vs 12.1%, RR = 0.98, 95% CI 0.90-1.07). Mortality rates were also similar between randomized treatments in the pre-defined subgroups: sex, age above and below 70 years, with and without previous myocardial infarction, Killip class at entry and randomization within 3 h or between 3 and 6 h from onset of symptoms. Reinfarction and cerebrovascular accidents were similar in all treatment groups. Adjusted analysis (Cox model) indicated that age and higher Killip class were the most important predictors of a poor prognosis. Previous myocardial infarction, female sex and longer delay from onset of symptoms were also indicators. Patients treated with SK plus heparin have a statistically significant better survival than the others, although the statistical significance of the remaining absolute difference disappears once the substantial proportion of patients dying in the first 12 h is excluded, when, by design, no heparin was given.