QT dispersion: an indication of arrhythmia risk in patients with long QT intervals.

TLDR

Recovery time homogeneity protects against arrhythmias, whereas dispersion is arrhythmogenic; a single ECG QT interval cannot reveal dispersion, but the difference between maximum and minimum QT intervals may be relevant. The study tested whether QTc dispersion differs between patients with arrhythmogenic long‑QT syndromes or drug‑induced arrhythmias and those with sotalol‑induced prolonged QT without arrhythmias. QTc dispersion was measured in 10 arrhythmogenic long‑QT patients and 14 sotalol‑treated patients without arrhythmias. QTc dispersion was significantly greater in the arrhythmogenic QT group than in the sotalol QT group, distinguished patients with ventricular arrhythmias from those without, and supports that QT dispersion reflects spatial differences in myocardial recovery time, potentially aiding arrhythmia risk assessment and antiarrhythmic drug efficacy.

Abstract

Homogeneity of recovery time protects against arrhythmias whereas dispersion of recovery time is arrhythmogenic. A single surface electrocardiographic QT interval gives no information on recovery time dispersion but the difference between the maximum and minimum body surface QT interval may be relevant. This hypothesis was tested by measuring the dispersion of the corrected QT interval (QTc) in 10 patients with an arrhythmogenic long QT interval (Romano Ward and Jervell and Lange-Nielsen syndromes or drug arrhythmogenicity) and in 14 patients without arrhythmias in whom the QT interval was prolonged by sotalol. QTc dispersion was significantly greater in the arrhythmogenic QT group than in the sotalol QT group. In patients with prolonged QT intervals, QT dispersion distinguished between those with ventricular arrhythmias and those without. This supports the hypothesis that QT dispersion reflects spatial differences in myocardial recovery time. QT dispersion may be useful in the assessment of both arrhythmia risk and the efficacy of antiarrhythmic drugs.