Associations between changes in city and address specific temperature and QT interval--the VA Normative Aging Study

Area of Science:

• Environmental Health
• Cardiology
• Gerontology

Background:

• Mechanisms linking ambient temperature, especially daily variability, to cardiovascular disease remain unclear.
• The heart rate-corrected QT interval (QTc) is a marker of ventricular repolarization and a predictor of cardiovascular events.

Purpose of the Study:

• To investigate the association between daily temperature metrics and QTc duration in older men.
• To explore the impact of daily mean temperature and temperature variability on ventricular repolarization.

Main Methods:

• A prospective cohort study of 487 older men (VA Normative Aging Study, 2000-2008) with up to three visits.
• Time-varying linear mixed-effect regression analyzed QTc associations with various moving averages of daily temperature (mean and standard deviation).
• Evaluated effect modification by season, diabetes, coronary heart disease, obesity, and age.

Main Results:

• Higher mean temperatures were associated with longer QTc at 21- and 28-day moving averages.
• Increased daily temperature standard deviation was linked to longer QTc across moving averages (4-28 days).
• A 1.9°C IQR increase in 4-day SD of temperature correlated with a 2.8 msec longer QTc; associations were stronger in colder months and in those with diabetes or CHD.

Conclusions:

• Elevated mean temperature and increased temperature variability are associated with prolonged QTc in older men.
• These associations are particularly pronounced in colder months and in individuals with pre-existing conditions like diabetes and coronary heart disease.
• Findings suggest a potential mechanism underlying temperature-related cardiovascular morbidity and mortality in the elderly.