Extent of ST-segment deviation in the single ECG lead of maximum deviationpresent 90 or 180 minutes after start of thrombolytic therapy best predicts outcome in acute myocardial infarction

In evolving myocardial infarction the extent of ST segment deviation reflec ts the existing ischemic myocardial injury and thus conveys very useful ear ly prognostic information. In recent years, the sum of ST segment elevation resolution (sum STR) has been proven to be an excellent early prognostic i ndicator. However, the predictive power of sum STR has never been systemati cally compared with that of other methods of evaluation of ST segment devia tion recovery. We, therefore, proposed to compare the prognostic power of S T segment changes evaluated by either sum STR or by ST segment resolution i n only the one lead showing the maximal deviation (lead STR) or only by the existing ST segment deviation in the single ECG lead of maximum ST deviati on present at a given time point after thrombolysis (lead STE). Methods and results In conjunction with the Intravenous nPA for Treatment of Infarctin g Myocardium. Early (InTIME) II Study, which compared mortality in patients with acute myocardial infarction randomized within 6 hours of symptom onse t to receive either Lanoteplase or Alteplase, all 3593 German and Polish pa tients participated in an ST segment resolution substudy. A 12-lead ECG was recorded at baseline and at 90 and at 180 minutes after start of thromboly tic therapy. The areas under the receiver-operating characteristic (ROC) cu rves to compare the power to predict 30 day cardiac mortality for sum STR, lead STR, and lead STE were at 90 min 0.686, 0.714, and 0.761 (p<0.002), an d at 180 min 0.678, 0.703, and 0.755 (p<0.001), respectively. In multivaria te analysis lead STE was an independent predictor of outcome even when adju stment was made for sum STR, lead STR, and clinical variables. Cardiac mort ality rates at 30 days for lead STE risk groups, classified as low, medium, or high (percent of patients in brackets), were at 90 min 1.0% (43%), 4.0% (32%), and 12.8% (25%), and at 180 min 1.5% (55%), 3.8% (31%), and 15.2% ( 14%), respectively. Conclusions Simple measurement of the ST segment deviat ion existing in the one ECG lead with the greatest deviation on the ECG rec orded 90 or 180 minutes after thrombolysis enables the identification of th e major subsets of patients who are either at very low or exceptionally hig h risk of mortality.