Effect of dofetilide on QT dispersion and the prognostic implications of changes in QT dispersion for patients with congestive heart failure.

AIMS

Drug-induced changes in QT dispersion may be a way of detecting harmful repolarisation abnormalities for patients receiving antiarrhythmic drugs affecting ventricular repolarisation.

METHODS AND RESULTS

In 463 congestive heart failure (CHF) patients enrolled in the Danish Investigations Of Arrhythmia and Mortality On Dofetilide-CHF (DIAMOND-CHF) study, both pre-treatment and on-treatment day 2-6 QT dispersion was available from standard 12-lead ECGs. Patients were randomised in a double-blind manner to receive either placebo or dofetilide, a new class III antiarrhythmic drug. During a median follow-up of 19 months (minimum 1 year), 179 patients (39%) died (135 patients from cardiac causes). Changes in QT dispersion did not predict all-cause or cardiac mortality for patients treated with dofetilide in multivariate survival analysis (Risk ratio: 1.02, 95% confidence interval: 0.97-1.08, P>0.4). This finding was independent of pre-treatment QT dispersion. Dofetilide caused a small QT dispersion increment of 8 ms, not different from the changes seen in the placebo group (3 ms).

CONCLUSION

For patients with CHF and reduced left ventricular systolic function, changes in QT dispersion following treatment with dofetilide do not predict all-cause or cardiac mortality. The dofetilide-induced QT dispersion changes are small and comparable to those seen in placebo treated patients.