Estimate of sample size For the following conditions: α = 0.05 (2 tailed), power: 80% (β = 0.20) and assuming a composite event incidence rate (death, reinfarction and disabling CVA) based on previous registries (21.7% in the fibrinolysis group and 12.8% in the PA group), a sample size of 282 patients per group is needed to demonstrate that difference (8.9% in absolute terms and 40% in relative terms). Assuming a loss to follow-up rate of 1%, the total number is 570 patients