Body surface distribution of abnormally low QRST areas in patients with Wolff-Parkinson-White syndrome. Evidence for continuation of repolarization abnormalities before and after catheter ablation.

Abstract

BACKGROUND Whether the Wolff-Parkinson-White syndrome (WPW) is associated with repolarization abnormalities is controversial. The QRST isointegral map (I-map) is theoretically independent of the activation sequence and dependent on repolarization properties. There have been no reports concerning the effects of radiofrequency (RF) catheter ablation of accessory pathway (AP) on repolarization properties analyzed by I-mapping. METHODS AND RESULTS I-maps were constructed from data recorded in 38 patients with WPW to investigate repolarization properties and their body surface distribution in a physiological state, without pharmacological influences, and in 13 ablated patients to elucidate the effects of RF ablation on repolarization properties. Patients were divided into three groups: group A, 15 patients with type A WPW (left-sided AP); group B, 10 patients with type B (right-sided AP); and group C, 13 patients who were successfully ablated. Group C consisted of three subgroups: subgroup CA, 7 patients with type A WPW; subgroup CB, 3 patients with type B WPW; and subgroup CC, 3 patients with concealed WPW. Controls consisted of 608 normals. Although I-maps of WPW were highly (r = .87) correlated with the mean normal I-map, the location of the minimum in groups A and B differed significantly from that in normals. The minimum was located over the upper right anterior chest in normal subjects, over the back in 82% of 22 patients with type A WPW including ablated patients (groups A+CA), and over the mid to lower right anterior chest in 62% of 13 patients with type B WPW including ablated patients (groups B+CB). Groups A+CA and B+CB had an abnormally low QRST area ("-2SD area") over the back and right anterior chest, respectively. The abnormally located minimum and the "-2SD area" were present in 7 of 10 ablated patients with manifest WPW (groups CA+CB). After RF ablation, the distribution of the minimum, initially abnormal, became normal over a period of days or weeks, and the "-2SD area" disappeared over 1 week in all 7 patients. Correlation coefficients between I-maps and the mean normal I-map increased after RF ablation. CONCLUSIONS (1) WPW is often associated with abnormalities in repolarization properties. (2) Repolarization abnormalities were located over the back in type A WPW and over the right mid to lower chest in type B WPW: (3) The abnormalities remain immediately after RF ablation and gradually normalize. These findings support the concept that ST-T abnormalities in 12-lead ECGs following RF ablation are attributable to "cardiac memory."