Benefits and risks of thrombolysis for acute myocardial infarction

Thrombolytic therapy is a major step forward in the treatment of acute myocardial infarction and may result in up to 50% mortality reduction, provided that it is administered early (chapter 1). In 80 to 85% of patients with suspected acute myocardial infarction, a coronary artery is blocked by a clot. With thrombolytic therapy the closed coronary artery is desobstructed in may cases, is infarct size limited and left ventricular function preserved. Several thrombolytic agents are available for clinical use: streptokinase, APSAC, urokinase and more recently recombinant tissue-type plasminogen activator (rt-PA or alteplase). The latter is the genetically engineered natural occurring plasminogen activator. Which agent is superior is still a matter of debate. Unlike streptokinase, APSAC and urokinase, rt-PA dissolves blood clots without degradation of circulating fibrinogen during in vitro and in animal experiments, provided that the dose does not exceed a certain threshold. This property of rt-PA is called fibrinspecificity. In this thesis the effect of rt-PA on coronary patency, infarct size, left ventricular function and clinical outcome is reported, as assessed in the clinical trials of the European Cooperative Study Group. In these trials patients with symptoms of acute myocardial infarction and fulfilling strict criteria for ST-segment change were entered. In addition, more general questions are addressed in this thesis: whether all patients with suspected acute myocardial infarction should receive thrombolytic therapy and whether coronary angiography before hospital discharge is indicated in all patients receiving thrombolytic therapy