QT-Interval Duration and Mortality Rate

Abstract

Abnormal prolongation and shortening of the electrocardiographic QT-interval duration, similar to those seen in hereditary forms of long and short QT syndromes, are associated with increased risk for ventricular arrhythmias and sudden cardiac death.^1-5 The effect of less extreme variations in QT-interval duration on mortality, however, is controversial. Some studies have shown associations between smaller increases in QT-interval duration and total mortality, cardiovascular mortality, and sudden cardiac death,^6-17 but these associations have not been replicated consistently in all studies.^18-20 Furthermore, although a short duration of the QT interval also may be associated with increased mortality, most studies have used broad categorizations of QT-interval durations that make it difficult to estimate precisely the dose-response relationships between QT interval and mortality. The purpose of this analysis was to investigate the association between QT-interval duration and total mortality and mortality due to cardiovascular disease (CVD), coronary heart disease (CHD), and non-CVD causes in a representative sample of the general US population using flexible methods to identify potential variations in mortality risks along the full spectrum of QT-interval durations.