Thrombolytic therapy for evolving myocardial infarction needs an approach that integrates benefit and risk

Thrombolytic therapy is a major step forward in the treatment of acute myocardial infarction and results in substantial reduction of mortality. However, in individual patients the benefits and bleeding risk are difficult to estimate, especially when benefit seems snail oi outweighed by the risk of intracranial bleeding For this and other reasons less than half the patients with evolving myocardial infarction are treated with thrombolytic therapy. We propose to approach the decision 'to treat or not to treat' in a systematic way, integrating estimated benefit and intracranial bleeding risk in individual patients. According to a decision-model developed with currently available medical knowledge, thrombolytic therapy appears beneficial in the majority of patients with evolving myocardial infarction provided that ST segment elevation is present and treatment can be started within 12 h of onset of symptoms. Thrombolytic therapy is wan anted in the absence of risk factors for intracranial haemorrhage, even if the risk of cardiac death in the first year without thrombolytic therapy is as low as 2.3% (Patients, with small inferior wall infarctions). For patients with increased intracranial bleeding risk, the cardiac baseline risk without thrombolytic therapy and treatment delay become important variables to take into account when selecting thrombolytic therapy. Precise thresholds for these variables are presented.