Longitudinal Community-Based Study of QT Interval and Mortality in Southeast Asians

Introduction
The 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.
Methods
The 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).
Results
Over 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).
Conclusions
We provide the first community-based estimates of the independent association of QT prolongation with all-cause mortality and cardiovascular events in Southeast Asians.