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

UNLABELLED

In evolving myocardial infarction the extent of ST segment deviation reflects the existing ischemic myocardial injury and thus conveys very useful early prognostic information. In recent years, the sum of ST segment elevation resolution (sum STR) has been proven to be an excellent early prognostic indicator. However, the predictive power of sum STR has never been systematically compared with that of other methods of evaluation of ST segment deviation recovery. We, therefore, proposed to compare the prognostic power of ST segment changes evaluated by either sum STR or by ST segment resolution in 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 deviation present at a given time point after thrombolysis (lead STE).

METHODS AND RESULTS

In conjunction with the Intravenous nPA for Treatment of Infarcting Myocardium Early (InTIME) II Study, which compared mortality in patients with acute myocardial infarction randomized within 6 hours of symptom onset to receive either Lanoteplase or Alteplase, all 3593 German and Polish patients 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 thrombolytic therapy. The areas under the receiver-operating characteristic (ROC) curves 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), and at 180 min 0.678, 0.703, and 0.755 (p < 0.001), respectively. In multivariate analysis lead STE was an independent predictor of outcome even when adjustment was made for sum STR, lead STR, and clinical variables. Cardiac mortality 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 deviation existing in the one ECG lead with the greatest deviation on the ECG recorded 90 or 180 minutes after thrombolysis enables the identification of the major subsets of patients who are either at very low or exceptionally high risk of mortality.