QRST time integral values in 12-lead electrocardiograms before and after radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome

Objectives. We investigated the usefulness of QRST values obtained from 12-lead electrocardiograms (ECGs) for identification of repolarization abnormalities before and after radiofrequency ablation in patients with Wolff-Parkinson-White syndrome. Background. Marked T wave abnormalities often appear after ablation and have been attributed to continuation of repolarization abnormalities present before ablation (cardiac memory). However, to our knowledge repolarization properties before and after ablation have not been assessed quantitatively. Methods. We calculated the ECG QRST values from 53 patients with Wolff-Parkinson-White syndrome and compared these values before, immediately after and 1 day and 1 week after successful ablation in 25 patients. Results. QRST values were abnormally high in lead V1 in 7 of 28 patients with left-sided accessory pathway and abnormally low in leads III and aVF and high in lead aVL in 12, 9 and 10 of 20 patients, respectively, with right-sided accessory pathway. Preexisting QRST abnormalities were still present immediately and 1 day after ablation but were usually absent by 1 week after ablation. QRST values before, immediately after and 1 day after ablation were not significantly different in any lead. In 14 patients with ablation of left-sided accessory pathway, QRST values before, immediately after and 1 day after ablation in lead V1 and immediately after ablation in leads I, aVR and V2 were significantly different from QRST values in those leads 1 week after ablation. In six patients with ablation of right-sided accessory pathway, QRST values before, immediately after and 1 day after ablation in leads III, aVL and aVF and immediately after ablation in lead II were significantly different from QRST values in those leads 1 week after ablation. Conclusions. Electrocardiographic QRST values may provide useful quantitative information with respect to repolarization properties before and after ablation in patients with Wolff-Parkinson-White syndrome that is otherwise difficult to obtain by conventional ECG analysis.