COMBINED TIME-DOMAIN AND SPECTRAL TURBULENCE ANALYSIS OF THE SIGNAL-AVERAGED ECG IMPROVES ITS PREDICTIVE ACCURACY IN POSTINFARCTION PATIENTS

The predictive accuracy of time-domain (TD) late potential analysis of the signal-averaged electrocardiogram in postmyocardial infarction (M I) is limited by the high incidence of false positives in inferior MI. However, frequency-domain spectral turbulence (ST) analysis suffers f rom a high incidence of false positives, especially in anterior MI. A prospective study was conducted of 262 patients with acute MI to inves tigate the hypothesis that combined TD and ST analyses of the signal-a veraged electrocardiogram could improve its predictive accuracy for se rious arrhythmic events in the post-MI period. Abnormal TD criteria we re RMS40 less than 25 mu V at 25 Hz plus RMS40 less than 16 mu V at 40 Hz, and abnormal ST criteria were a turbulence score of 3 or 4. Seven teen patients had arrhythmic events during 10.5 +/- 2.4 months of foll ow-up evaluation (13 sudden cardiac death judged to be due to arrhythm ia and 4 nonfatal sustained ventricular tachycardia). The total predic tive accuracy of combined TD and ST (92%) was higher than TD (87%), wh ereas ST had the lowest total predictive accuracy of 78%. The negative predictive accuracy of all three analyses was high (96-97%). However, the positive predictive accuracy of TD (28%) was higher than ST (14%) . Combined TD and ST significantly improved the positive predictive ac curacy of the test to 35% in the total group and to 40% in patients wi th first anterior or inferior Mi. The best results were obtained in pa tients with first anterior MI, where the positive predictive accuracy of combined analysis was 50%.