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ST segment changes as a surrogate end point in coronary thrombolysis.

The role ofthrombolysis in the treatment of acute myocardial infarction is now established by the GISSI study, which was presented at the time ofthe American College of Cardiology scientific sessions in New Orleans in March 1990. The enormous size and costs required to measure the difference in mortality in comparative trials impose many limitations and in future small specific subsets will need to be studied. There is increasing interest in examining surrogate end points for coronary artery patency in such studies. The extent of the improvement in left ventricular function shown after reperfusion is disproportionately small compared with the associated reduction in mortality, suggesting that reperfusion has an as yet unidentified benefit. The patency of the infarct related vessel therefore remains the main goal of treatment and coronary arteriography remains the "gold standard" for the assessment ofreperfusion. Identification ofreperfusion is important in the assessment of the efficacy of new thrombolytic agents, differing regimens of administration of available agents (such as bolus dosing), or the role of adjunctive medication such as antiplatelet treatment. The identification of arteries that remain occluded is also important because it predicts a higher mortality in some patients, who might benefit from early additional intervention such as intracoronary thrombolysis or salvage angioplasty. The complications associated with early angiography have been overestimated because they may include those of angioplasty with its additional risk of bleeding complications and coronary artery occlusion. Further assessment of the risk-benefit ratio of angiography in acute myocardial infarction is required, because the management of patients may be improved by the identification of the number of diseased vessels, the patency or occlusion of the infarct related artery, and early assessment of left ventricular function. A recent trial to compare the angiographically demonstrated patency rates achieved after the administration of either anistreplase or streptokinase focused attention on the ethical aspects of performing invasive procedures early after myocardial infarction in the presence of thrombolysis."2 We need to know more about the risks of local haemorrhage, bleeding at distant sites, and the morbidity associated with angiography.