[The relation between QT dispersion and incidence of ventricular premature beats in patients after myocardial infarction].

The relation between increased QT dispersion and ventricular arrhythmias in patients after myocardial infarction is not definitely confirmed. The diurnal variation and long-term changes in QT dispersion can be a substantial cause of conflicting results presented in follow-up studies that tested the prognostic significance of QT dispersion. The present study was designed to determine the relation between incidence of ventricular premature beats (VPBs) and magnitude of QT dispersion measured in sinus beats before VPBs occurrence. The study group consisted of 306 postinfarction patients including 153 patients with VPBs and 153 patients without VPBs on a routine ECG. QT dispersion was calculated as the difference between the maximum and the minimum QT intervals across a 12-lead ECG. In the group of patients with VPBs the mean value of QT dispersion was greater than in the group without VPBs (81 +/- 40 ms versus 56 +/- 33 ms, p < 0.0001). The results of univariate analysis indicated that QT dispersion > 60 ms, corrected QT interval > 465 ms, QRS complex > 100 ms and RR interval < or = 800 ms were all associated with VPBs incidence. Discriminant analysis of these variables revealed that QT dispersion > 60 ms was the strongest indicator of VPBs recorded on a routine ECG (F = 47.88; p < 0.0001). Increased QT dispersion is an electrocardiographic marker of susceptibility to ventricular premature beats in patients after myocardial infarction.