Impending Crisis: Anticipated Rise in Heat-Related Cardiovascular Fatalities

It is anticipated that the United States will experience an increase in cardiovascular fatalities attributed to extreme heat in the span from 2036 to 2065. Researchers, with funding from the National Institutes of Health, associate the expected upsurge with an increase in the number of summer days experiencing heat indices topping 90 degrees. The projection is based on historical data and future climate modeling, underscoring the urgency of implementing cooling strategies and recognizing the worldwide ramifications.

The NIH-sponsored research forecasts that the greatest impact will be on the elderly and African American populations.

An increase in deaths linked to cardiovascular conditions as a result of intense heat is projected during the years 2036 to 2065 in the United States, as per a National Institutes of Health-backed study. The research, published in the American Heart Association’s journal Circulation, foresees that individuals over the age of 65 and African Americans will be disproportionately impacted.

At-Risk Groups and Elevated Heat Indices

Currently, extreme heat events contribute to under 1% of deaths related to cardiovascular conditions. However, predictive models suggest a shift due to an expected increase in the number of summer days with perceived temperatures of 90 degrees or above. This heat index, which combines temperature with humidity to reflect the actual experienced heat, is set to become a critical measure of temperature extremes. The most at-risk populations include the elderly and African Americans, many of whom suffer from pre-existing medical conditions or confront socioeconomic hurdles that affect their health, such as lack of access to air conditioning or residence in urban heat islands.

“Extreme heat’s impact on health is predicted to intensify in the coming decades,” indicates Sameed A. Khatana, M.D., M.P.H., one of the study’s authors, a cardiologist, and an assistant professor at the University of Pennsylvania in Philadelphia. “The disproportionate effect of heat on different demographics also highlights concerns of health equity and the potential intensification of existing health disparities.”

Research Approach and Conclusions

The researchers analyzed county-level mortality data from cardiovascular disease across the contiguous United States during May to September from 2008 to 2019, a period that recorded over 12 million such fatalities. They also utilized environmental projections indicating that each summer, the heat index reached 90 degrees approximately 54 times. The analysis connected these extreme temperature occurrences with an annual average of 1,651 cardiovascular deaths nationwide. The Southern and Southwestern regions saw more significant effects compared to the Northwest and Northeast.

Projections and Consequences for the Future

Researchers employed environmental and demographic predictive analyses for the years 2036–2065, estimating that the number of summer days with temperatures feeling like 90 degrees or hotter could range between 71 to 80. Based on these projections, the annual number of heat-related cardiovascular fatalities could rise 2.6-fold for the general populace—from 1,651 to 4,320—assuming minimal greenhouse gas emissions. Should emissions escalate, the deaths could more than triple to 5,491.

For the elderly and African American adults, the future scenario appears more severe. For those 65 and older, fatalities might almost triple, rising from 1,340 to 3,842 with current emission levels—or to 4,894 should emissions increase. For African Americans, the death toll could more than triple, from 325 to between 1,512 and 2,063.

The study also took into account varying factors like age, pre-existing health conditions, and geographic location when comparing current and future populations.

While many adapt to extreme heat through natural cooling mechanisms like sweating, those with chronic health conditions, including diabetes and heart disease, may react differently, increasing the risk of heart attacks, arrhythmias, or strokes.

“Although a small fraction of the adult population currently suffers cardiovascular incidents due to heat, this study highlights the importance of preventive measures for those at risk,” states Lawrence J. Fine, M.D., of the Division of Cardiovascular Sciences at the NHLBI, NIH.

Preventive Measures and Worldwide Impact

The study outlines several cooling measures employed by urban areas, including tree planting for shade, establishing air-conditioned centers, and using materials on streets and roofs that reflect heat. Further research is essential to determine the effectiveness of such interventions on public health.

“Beyond considering the United States, these predictive models also cast light on the potential global effects of extreme heat, particularly in warmer regions already dealing with significant health disparities,” notes Flora N. Katz, Ph.D., from the NIH Fogarty International Center.

For additional information on this research:

Anticipated Surge in U.S. Cardiovascular Deaths Driven by Extreme Heat
Skyrocketing Cardiovascular Deaths from Extreme Heat Forecasted

Reference: “Projected Change in the Burden of Excess Cardiovascular Deaths Associated With Extreme Heat by Midcentury (2036–2065) in the Contiguous United States” by Sameed Ahmed M. Khatana et al., Circulation, 30 October 2023.
DOI: 10.1161/CIRCULATIONAHA.123.066017

The research received partial funding from NHLBI grant K23 HL153772.

Frequently Asked Questions (FAQs) about Heat-related cardiovascular mortality

More about Heat-related cardiovascular mortality

• Projected Surge in Heat-Related Cardiovascular Deaths
• NIH Study on Climate Impact and Health Equity
• Cardiovascular Health and Extreme Heat
• Adapting Urban Environments for Heatwaves
• Global Implications of Rising Heat Indices