Comparison of the predictive value of ST segment elevation resolution at 90 and 180 min after start of streptokinase in acute myocardial infarction. A substudy of the hirudin for improvement of thrombolysis (HIT)-4 study.

AIMS Previous studies revealed that >/=70% or <30% ST segment elevation resolution 180 min after the start of thrombolysis is a strong predictor of either favourable or poor outcome. The aim of this study was to compare the prognostic value of ST segment elevation resolution at 90 and 180 min after the start of streptokinase infusion. METHODS AND RESULTS The Hirudin for Improvement of Thrombolysis (HIT)-4 study of 1208 patients compared streptokinase therapy in conjunction with either r-hirudin or heparin. Complete ST segment elevation resolution (>/=70%) at 90 and 180 min identified 25% and 50%, respectively, of all patients with a 30 day cardiac mortality of less than 2%. Forty-four percent of patients had no ST segment elevation resolution (<30%) at 90 min and the 30 day cardiac mortality was 7.3%. At 180 min, the no ST segment elevation resolution group decreased to 15% of all patients while the mortality risk increased to 13.6%. CONCLUSIONS ST segment elevation resolution is a useful tool for early risk stratification and the strategy of rescue angioplasty. Complete ST segment elevation resolution within 180 min of the start of streptokinase therapy indicates excellent survival prospects in 50% of patients. A half of these low risk patients can be identified at 90 min. A high risk group appears to be best characterized by no ST segment elevation resolution at 180 min rather than at 90 min.