The prognostic value of QTc interval and QT dispersion following myocardial infarction in patients treated with or without dofetilide.

BACKGROUND

Acute myocardial infarction (MI) is associated with an increased risk of death, with a 1-year mortality close to 10% in patients discharged from hospital alive. During the first year following MI, close to 50% of deaths are assumed to be due to arrhythmic events.

HYPOTHESIS

The study was undertaken to determine the interaction between dofetilide treatment and pretreatment QTc interval and QT dispersion regarding mortality in patients with left ventricular (LV) dysfunction and a recent MI.

METHODS

The study population consisted of 894 patients with a recent MI and LV systolic dysfunction, who were randomized to receive dofetilide or placebo. The study was a substudy of the Danish Investigations of Arrhythmia and Mortality on Dofetilide-MI (DIAMOND-MI).

RESULTS

During a minimum of 1-year follow-up, 261 (29%) patients died. Baseline QTc interval did not hold any prognostic value on mortality for placebo-treated patients. When pretreatment QTc interval was <429 ms, dofetilide resulted in a 45% reduction of mortality (hazard ratio 0.55, 95% confidence limits 0.34-0.88, p<0.02) compared with placebo. When QTc interval was >429 ms, dofetilide did not influence mortality significantly. This study revealed no statistically significant relation between QT dispersion, dofetilide treatment, and mortality.

CONCLUSION

In patients with a recent MI, LV dysfunction, and a short baseline QTc interval, dofetilide is associated with significant survival benefit. This benefit is not seen with a longer QTc interval. QT dispersion is not a risk factor in this population.