BACKGROUND: Increased QTc dispersion has been associated with an increased
risk for ventricular arrhythmias and cardiac death in selected patient
populations. We examined the association between computerized
QTc-dispersion measurements and mortality in a prospective analysis of the
population-based Rotterdam Study among men and women aged > or = 55 years.
METHODS AND RESULTS: QTc dispersion was computed with the use of the
Modular ECG Analysis System as the difference between the maximum and
minimum QTc intervals in 12 and 8 leads (ie, the 6 precordial leads, the
shortest extremity lead, and the median of the 5 other extremity leads).
After exclusion of those without a digitally stored ECG, the population
consisted of 2358 men and 3454 women. During the 3 to 6.5 years (mean, 4
years) of follow-up, 568 subjects (9.8%) died. The degree of QTc
dispersion was categorized into tertiles. Data were analyzed using the Cox
proportional hazards model, with adjustment for age. For QTc dispersion in
8 leads, those in the highest tertile relative to the lowest tertile had a
twofold risk for cardiac death (hazard ratio, 2.5; 95% confidence interval
[CI], 1.6 to 4.0) and sudden cardiac death (hazard ratio, 1.9; 95% CI, 1.0
to 3.7) and a 40% increased risk for total mortality (hazard ratio, 1.4;
95% CI, 1.2 to 1.8). Additional adjustment for potential confounders,
including history of myocardial infarction, hypertension, and overall QTc,
did not materially change the risk estimates. Hazard ratios for QTc
dispersion in 12 leads were comparable to those found for QTc dispersion
in 8 leads. CONCLUSIONS: QTc dispersion is an important predictor of
cardiac mortality in older men and women.