IntroductionThe prognostic impact of QT interval prolongation has not been well studied in healthy Asians. We investigated the association between the QT interval with mortality and cardiovascular events in a healthy Southeast Asian population.MethodsThe QT interval corrected for heart rate using the Bazett’s formula (QTc) was measured in 2536 (825 men, mean age 65.7±7.5 years) Singaporean adults free of cardiovascular disease in the population-based Singapore Longitudinal Ageing Study. Outcomes were all-cause mortality and incident cardiovascular events (cardiovascular mortality, myocardial infarction (MI) and/or stroke).ResultsOver a mean 7.78 years (19695 person-years) of follow-up, there were 202 deaths (45 from cardiovascular causes), 62 cases of myocardial infarction and 64 cases of stroke. Adjusting for age, sex, and cardiovascular risk factors, QTcB prolongation remained independently associated with increased all-cause mortality (HR(per standard deviation) 1.27 (1.10–1.48), p = 0.0015), as well as increased risk of cardiovascular events (HR 1.20 (1.01–1.43), p = 0.0415) and MI/stroke (HR 1.22 (1.01–1.47), p = 0.0455), but not cardiovascular mortality alone (HR 1.05 (0.77–1.44), p = 0.7562).ConclusionsWe provide the first community-based estimates of the independent association of QT prolongation with all-cause mortality and cardiovascular events in Southeast Asians.

The Tecumseh Community Health Study is a longitudinal, ongoing prospective epidemiologic study of a natural community's health and disease status. Data have been collected on the Tecumseh population in southeast Michigan for over 30 years, beginning with a 1957 canvass of all households and adding all newcomers to the community until 1970, after which only previous residents have been followed. The Tecumseh project has conducted over 80 different studies, including both disease-specific investigations and studies concerned with the prevalence and incidence of disease in the community. The core data file for the years 1959-1969 contains data collected in Round I: 1959-1960, Round II: 1962-1965, and Round III: 1967-1969 (referred to as the Cardiovascular Studies I, II, and III, and the General Surveillance Study II). These data include information taken from baseline medical history interviews, medical examinations, clinical measurements, laboratory work, and electrocardiograms. Mortality status of all persons at the time of attempted or actual contact in Round III is also provided. The major variable groups include demographic information, family history of major diseases, systematic review of present and past symptoms and conditions, smoking and drinking habits, physical examinations, measurements and laboratory work, and electrocardiogram results.

Sex-stratified association of QTcB (categorical) with overall and cardiovascular mortality.

Association of QTc B (continuous) with overall and cardiovascular mortality.