Extreme Heat Is Linked to Deaths From Heart Disease

Extreme heat accounted for about 600 to 700 additional deaths from cardiovascular disease annually over a decade-long period in the United States, according to the results of a study presented at the American College of Cardiology’s 71st Annual Scientific Session.

The spike in deaths during heat waves was most prominent among men and non-Hispanic Black adults, which could suggest that climate change may exacerbate existing heart disease disparities for these groups.

Extreme heat has been on the rise in the United States, with approximately 3 times as many heat waves per year compared with the 1960s, because of climate change. Heat can cause increase strain on the heart and trigger cardiac events, such as heart attacks.

Additionally, cardiovascular disease risk factors, such as diabetes and taking heart medications, such as beta blockers and diuretics, can affect an individual’s ability to regulate body temperature.

This study is one of the first to assess trends in heart disease during extreme heat events on a nationwide scale. Previous studies focused on specific cities or relied on heat being listed as the cause of death, which likely underestimated the true toll of these events, investigators said.

“These results suggest the full extent of the adverse health effects of extreme heat is broader than previously realized,” Sameed Ahmed Khatana, MD, an assistant professor of medicine at the University of Pennsylvania, said in a statement. “Climate change and its consequences will have a very large impact on our society in terms of health, and cardiovascular health is an important component of that.”

Investigators analyzed cardiovascular mortality and temperature trends in all 3108 counties in the contiguous United States. They used data from the CDC’s National Environmental Health Tracking Network to determine each county’s baseline average daily maximum temperature between 1979 and 2007.

Investigators identified that extreme heat days occurred in the decade between 2008 and 2017, which were defined as days when the heat index reached 90ºF or higher and the maximum heat index was in the 99th percentile of the daily maximum heat index in the baseline period for that day.

Additional data from the National Center for Health Statistics were used to assess trends in cardiovascular mortality for the same decade.

Overall, the results showed that each additional day of extreme heat in a month was associated with a 0.13% increase in deaths from heart disease, which averaged approximately 600 to 700 additional deaths per year across the decade studied. However, there were different trends observed among genders and racial groups.

For men, the extreme heat was associated with a 0.21% increase in cardiovascular mortality, but there was no significant association for women. Additionally, the non-Hispanic Black population saw an increase of about 0.27% in mortality, but there was no significant association for Hispanic or non-Hispanic white populations.

These findings suggest that the cardiovascular mortality burden of heat waves was disproportionate in Black communities and among men, according to investigators.

Investigators suspect that the higher proportion of men working in sectors where it can be harder to avoid heat exposure, such as agriculture and construction, could have resulted in part of this disparity. Furthermore, the higher risk among Black populations could be related to systemic health disparities and to differences in environments that have resulted from a history of discrimination and segregation in predominantly Black neighborhoods.

“Policy leaders also need to realize that climate negotiations have a real impact on people’s health here in the US and in their own communities,” Khatana said. “The health impacts of climate change have been happening for a while and are likely to continue to get worse with rising temperatures.”

Reference

As temperatures spike, so do deaths from heart disease. EurekAlert. News release. March 23, 2022. Accessed March 24, 2022. https://www.eurekalert.org/news-releases/947178