USE OF CHANGES IN ST SEGMENT ELEVATION FOR PREDICTION OF INFARCT ARTERY RECANALIZATION IN ACUTE MYOCARDIAL-INFARCTION

Background: The role of the ECG in evaluating reperfusion status after thrombolytic treatment in acute myocardial infarction is not clear. D ramatic ST segment changes have been observed during recanalization of an infarct-related artery, but ST criteria have not been definitively established for prediction of coronary artery patency. Differences in ST segment changes in relation to infarct localization have not been evaluated and further investigation is required into reciprocal ST dep ression, which provides information independent from ST elevation. The refore, the aim of this study was to evaluate how early changes in ST segment elevations and depressions predict vessel patency after fibrin olysis for patients with anterior and inferior/lateral infarcts. Metho ds and Results: Two hundred patients with a Pardee wave in the ECG and chest pain of less than 6 h duration were given thrombolytic treatmen t. The result of the therapy was assessed simultaneously with coronary angiography. Patients were divided into two groups. I (50 patients) w ithout recanalization (TIMI grade 0, 1 or 2), and II (150 patients) wi th successful recanalization (TIMI grade 3). Before and after therapy, analysis of the 12 lead ECG included maximum ST elevation measurement (H-1, H-2 respectively), the sum of ST elevation (Sigma H-1, Sigma H- 2), the sum of ST segment depressions (Sigma h(1), Sigma h(2)), and th e ratios of ST segment changes (R(1)=H-2:H-1, R(2)=Sigma H-2:Sigma H-1 , R(3)=Sigma h(2):Sigma h(1)). The mean interval from the first to the second ECG was 3.5 +/- 1 h. Successive values of R(1) and R(2) were e xamined to find that which best distinguished between the two groups. The best values for prediction of reperfusion were: (1) For anterior w all infarct Specificity Sensitivity R(1) less than or equal to 0.6 83. 3% 88.7% R(2) less than or equal to 0.5 83.3% 92.0% (2) For inferior a nd lateral infarct R(2) < 0.5 100% 93.8% R(2) < 0.5 100% 92.8% In 13 p atients with a complete right ol left bundle branch block in the fir s t or second ECG, the result of treatment was predicted in 11 patients using criteria for factor R(1) and in 12 patients using criteria ia fo r R(2). Analysis of ST segment depressions revealed a significant corr elation between normalization of ST segment depressions and elevations (R(3) vs R(1):r=0.60, P<0.05; R(3) vs R(2) r=0.59, P<0.05). Multivari ate discriminant analysis showed an independent value of R(3) for disc rimination between the two groups, but only in patients with inferior/ lateral infarcts. The overall accuracy of the common algorithm in pred icting reperfusion was significantly better in patients with inferior/ lateral infarcts (Chi(2) test, P=0.0078). When separate algorithms wer e used, there was no significant difference between patients with ante rior or inferior/lateral infarcts because of the significant improveme nt in prediction of reperfusion in patients with anterior infarcts (Mc Nemar's test: P=0.041). Conclusions: We conclude that analysis of ST s egments on the standard 12-lead ECG offers valuable help in the early identification of successful rcanalization of infarct-related arteries after thrombolytic therapy in patients with acute myocardial infarcti on. Use of the ratio of ST segment normalization according to the sepa rate criteria for anterior and inferior/latelal infarcts gives the tes t a high sensitivity and specificity, even in the presence of interven tricular conduction disturbances.