Predicting outcome after thrombolysis in acute myocardial infarction according to ST-segment resolution at 90 minutes: A substudy of the GUSTO-III trial

Background Resolution of ST-segment elevation after thrombolysis for acute myocardial infarction has been shown to have prognostic significance 3 hours (180 minutes) after the initiation of therapy. Whether prognostically useful information can be achieved as early as 90 minutes after thrombolysis is unknown. Methods An electrocardiographic substudy of 2352 patients from the Global Use of Strategies To Open occluded coronary arteries (GUSTO-III) trial was undertaken to compare outcomes according to ST-segment resolution at 90 minutes versus 180 minutes after administration of thrombolytic therapy. Results Of 2352 patients in the substudy, 2241 had a baseline and 90-minute electrocardiogram, and 22 18 had a baseline and 180-minute ECG. Complete ST-segment resolution occurred in 44.2% of patients at 90 minutes and 56.5% of patients at 180 minutes. ST-segment resolution at both 90 and 180 minutes was associated with lower 30-day and 1-year mortality. Multivariate analysis revealed ST-segment resolution at 90 minutes to be an equally strong predictor, of 30-day mortality as resolution at 180 minutes. Patients who were at particularly high risk for mortality were those aged >70 years, those who presented with Killip class >1, and those with anterior infarctions. Conclusions The presence of ST-segment resolution on standard 1 2-lead electrocardiographic monitoring 90 minutes after thrombolysis is a useful independent predictor of mortality at 30 days and 1 year. The potential for obtaining prognostic results as early as 90 minutes after thrombolysis sets a new precedent for optimum electrocardiographic monitoring times in these patients.