[Intravenous thrombolysis in acute myocardial infarct]

In two large randomized studies (ISAM and GISSI) a reduction in hospital mortality of about 15% was observed in patients treated within 6 hours after the onset of symptoms of myocardial infarction with a 1 hour intravenous infusion of 1.5 million U of streptokinase. In GISSI, early treatment within 1 hour from symptom onset reduced in-hospital mortality by about 47% (p = 0.0001). In spite of a significant limitation of infarct size by intravenous streptokinase in ISAM there was only a trend to a lower long-term mortality in patients with inferior myocardial infarction (10.2% versus 14.2% placebo), while in patients with anterior myocardial infarction long-term mortality was slightly higher in streptokinase-treated patients (19.0% versus 17.7%). Long-term mortality after hospital discharge strikingly increased in streptokinase patients, who had suffered a large anterior wall infarction (21.1% versus 6.9% placebo, p less than 0.007). An increased risk of dying cumulated in patients with rapid reperfusion, i.e. MB-CK peaking within 9 hours after the start of treatment. The potentially unstable situation in streptokinase-treated survivors of acute myocardial infarction suggests the need for additional mechanical or surgical interventions. Randomized prospective trials with sufficient statistical power are needed to ascertain the true impact of such "definite treatment".