Length of the QT interval: determinants and prognostic implications in a population-based prospective study of older men

ObjectiveWe examined potential determinants and prognostic value of the corrected QT interval (QTc).DesignA total of 4252 British men aged 60 to 79 years had a resting 12-lead electrocardiogram. Potential determinants of the QTc were assessed using multivariable regression. Men were followed up for 7 years.ResultsA 1 standard deviation increase in QTc (26 milliseconds) was associated with increased all-cause mortality (hazard ratio, 1.13; 95% confidence interval, 1.05-1.22). Longer QTc was associated with increasing age, preexisting coronary heart disease, and a range of drugs. Shorter QTc was present in diabetics and smokers. Corrected QT interval was related inversely with serum potassium and calcium and positively with serum urate, sodium, and systolic blood pressure. The relation of QTc to all-cause mortality was independent of adjustment for these factors.ConclusionsAge, preexisting coronary heart disease, certain medications and biochemical factors, and diabetes are independently associated with QTc. Corrected QT interval is an independent predictor of all-cause mortality.