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(Circulation. 1997;95:401-404.)
© 1997 American Heart Association, Inc.

Articles

Depolarization-Repolarization Inhomogeneity After Repair of Tetralogy of Fallot

The Substrate for Malignant Ventricular Tachycardia?

Michael A. Gatzoulis, MD; Jan A. Till, MD; Andrew N. Redington, FRCP

the Royal Brompton Hospital, National Heart and Lung Institute, Imperial College, London, UK.

Correspondence to Prof Andrew N. Redington, Royal Brompton Hospital/National Heart and Lung Institute, Sydney St, London SW3 6NP, UK.

Background We have previously shown that QRS prolongation (180 ms) is a risk marker for sustained ventricular tachycardia (VT) late after repair of tetralogy of Fallot (rTOF). We have now examined the dispersion of QT and its components QRS and JT, in an attempt to determine whether any association exists between these measurements and the presence of VT in these patients.

Methods and Results QRS duration and QT/QRS/JT dispersion were measured manually from standard ECGs in 10 syncopal rTOF patients (21.4±4.6 years after repair; group 1) with QRS180 ms and with documented VT and were compared with 9 rTOF patients with QRS 180 ms and no VT (group 2), 40 rTOF patients with QRS <180 ms and no clinical arrhythmias (group 3), and 40 nontetralogy control subjects (20 with right bundle-branch block [group 4] and 20 with normal ECG patterns [group 5]). Mean QT dispersion (62±36 ms) in the tetralogy patients was greater than in the nontetralogy control subjects (34±10 ms, P<.001). There were significant differences in all measured parameters between groups 1 and 3 and more importantly between groups 1 and 2. QRS dispersion in group 1 also correlated with QRS duration but not with JT dispersion.

Conclusions Our data suggest that both depolarization and repolarization abnormalities are associated with VT after rTOF. Furthermore, increased QT, QRS, and JT dispersions, combined with a QRS180 ms, refine risk stratification for VT in these patients.

Key Words: tetralogy of Fallot • arrhythmia • syncope • electrocardiography