INCREASED DISPERSION OF VENTRICULAR RECOVERY-TIME AS A NEW REPOLARIZATION ABNORMALITY IN THE WOLFF-PARKINSON-WHITE SYNDROME

The aim of our study was to assess whether the presence of ventricular preexcitation affects the spatial distribution of ventricular recover y time. Recent reports support the hypothesis that QT and QTc dispersi ons (QTd and QTcd) can be reliably adopted as a non-invasive parameter to estimate regional discrepancies of ventricular repolarization. The ECGs of 32 healthy subjects with Wolff-Parkinson-White syndrome and o f 29 normal individuals have been analysed using a Digitizer (Calcomp 9000), in order to obtain, for each subject, a mean QRS (M-QRS), QT (M -QTe), QTc (M-QTec), JT (M-JT), JTc (M-JTc) from all the measured inte rvals of the 12 standard ECG leads. QRS, QT and QTc dispersions (QRSd, QTd, QTcd) were defined as the difference between the maximal and min imal QRS, QTe and Qtec values calculated in the various leads. We atta ined the following results: patients with WPW syndrome exhibited, with respect to controls, longer M-QRS (P<0.001) and M-QTec (P<0.001) valu es, despite similar M-QTe (P=NS), M-JT (P=NS and M-JTc (P=NS). QRSd di d not differ in the two groups (P=NS), while QTd and QTcd both resulte d significantly greater in pre-excited subjects (P<0.001). In the WPW group, QRSd was not related either to QTd (r=0.325, P=NS) or to QTcd ( r=0.148, P=NS), while in the controls there was a significant relation between QRSd and both QTd (r=0.522, P=0.004) and QTcd (r=0.379, P=0.0 42). Our findings suggest that the presence of ventricular pre-excitat ion does not determine a prolongation of the mean ventricular recovery time, but increases regional discrepancies of the re-polarization pro cess. This assumption is supported by the observation of greater value s of QTd and QTcd associated with a similar QRSd.