Extremely abnormal prolongation of the electrocardiographic QT interval is associated with malignant ventricular arrhythmias and sudden cardiac death. However, the implications of variations in QT-interval length within normal limits for mortality in the general population are still unclear.
We performed a meta-analysis to investigate the relation of QT interval with mortality endpoints. Inverse-variance weighted random-effects models were used to summarize the relative risks across studies. Twenty-three observational studies were included.
The pooled relative risk estimates comparing the highest with the lowest categories of QT-interval length were 1.35 (95% confidence interval = 1.24–1.46) for total mortality, 1.51 (1.29–1.78) for cardiovascular mortality, 1.71 (1.36–2.15) for coronary heart disease mortality, and 1.44 (1.01–2.04) for sudden cardiac death. A 50 milliseconds increase in QT interval was associated with a relative risk of 1.20 (1.15–1.26) for total mortality, 1.29 (1.15–1.46) for cardiovascular mortality, 1.49 (1.25–1.76) for coronary heart disease mortality, and 1.24 (0.97–1.60) for sudden cardiac death.
We found consistent associations between prolonged QT interval and increased risk of total, cardiovascular, coronary, and sudden cardiac death. QT-interval length is a determinant of mortality in the general population.
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From the aDepartment of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD; bWelch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Medical Institutions, Baltimore, MD; cDivision of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD; and dDepartment of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain.
Submitted 19 November 2010; accepted 14 March 2011; posted 27 June 2011.
Supported by the National Center for Cardiovascular Research (CNIC Translational Cardiology grant 2008–03), the National Institutes of Health (grants ES015597 and HL091062), the Donald W. Reynolds Cardiovascular Clinical Research Center at Johns Hopkins University and the Fondation Leducq.
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Correspondence: Eliseo Guallar, Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Bloomberg School of Public Health, 2024 E. Monument Street, Room 2–639, Baltimore, MD 21205. E-mail: email@example.com.