QT and JT dispersion in patients with monomorphic or polymorphic ventricular tachycardia/ventricular fibrillation

Abstract

The present study evaluates the repolarization abnormalities in patients with monomorphic sustained ventricular tachycardia (MVT) and polymorphic ventricular tachycardia/ventricular fibrillation (PMVT/VF) by measuring QT and JT dispersion on the surface electrocardiogram (ECG). QT dispersion is a predictor of ventricular arrhythmias in several clinical settings. However, the value of QT and JT dispersion in identifying patients at risk for PMVT/VF is controversial. Maximum QT (JT) interval duration and QT (JT) dispersion were compared between 20 healthy individuals, 12 patients with inducible MVT during programmed electrical stimulation and seven patients with PMVT/VF recorded during 24-hour ambulatory ECG or induced by programmed electrical stimulation. QT dispersion was 40 ± 9 ms in the control group, 63 ± 21 ms in the MVT group, and 79 ± 31 ms in the PMVT/VF group. QT dispersion in both the MVT and PMVT/VF groups were significantly greater than in the control group ( P < .001 and P < .0001, respectively); however, there was no significant difference between the MVT and PMVT/VF groups. JT dispersion was 41 ± 14 ms in the control group, 69 ± 14 ms in the MVT group and 103 ± 37 ms in the PMVT/VF group. JT dispersion differed significantly between the study groups and was significantly increased in PMVT/VF group than in the control group or MVT groups ( P < .0001 vs. the control group, P < .005 vs. the MVT group). Patients with PMVT/VF have a greater dispersion of ventricular repolarization time. Repolarization abnormalities are important for ventricular arrhythmogenesis and detectable on the surface ECG.