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TOPLINE:

Cardiovascular disease (CVD) burden related to heat was projected to nearly triple by 2050 under a scenario of high emissions. The increase was driven mainly by premature deaths and amplified by population aging. Low-income counties were disproportionately affected.

METHODOLOGY:

• Researchers conducted a cross-sectional analysis of 2010-2016 data from 3108 US counties and county equivalents to estimate CVD burden related to heat in 2030 and 2050.
• They compared daily average temperatures to the ideal minimum-risk temperature of each county, summed the annual excess heat, and used published risk estimates per 1°C above that level to calculate the fraction of CVD caused by heat.
• Daily mean temperatures for each county were projected for 2030 and 2050 using downscaled climate models under two greenhouse gas scenarios: Shared Socioeconomic Pathway (SSP)2-4.5 (moderate emissions) and SSP5-8.5 (high emissions).
• The heat attributable fractions were applied to age-stratified baseline CVD burden to estimate future disability-adjusted life years (DALYs), years of life lost, and years lived with disability.
• Researchers also evaluated how population aging, income, and other factors would affect the projected burden.

TAKEAWAY:

• At baseline, the national median CVD burden attributable to heat was 138.5 DALYs per 100,000, driven mainly by years of life lost rather than years lived with disability.
• Under the scenario of high emissions (SSP5-8.5) by 2050, the median heat-attributable DALY increased to 418.2 per 100,000 (about a threefold increase). The increase was again driven by years of life lost, corresponding to about 50,000-70,000 additional cardiovascular deaths per year.
• Projected population aging alone was linked to a 34% increase in heat-attributable DALYs by 2050, independent of changes in temperature.
• Low- and middle-income counties and many Southern and Midwestern states showed the largest relative increases in DALYs, whereas Pacific Northwest counties had the highest baseline burden.

IN PRACTICE:

“As the [population attributable fractions] may triple by 2050, heat mitigation must become central to cardiovascular prevention, with comprehensive adaptation policies to prioritize the most vulnerable communities,” the researchers wrote.

“Recognizing and integrating ambient heat and broader environmental determinants into cardiovascular research, policy, and clinical care is not future aspirations — they are a present responsibility,” three experts wrote in an editorial accompanying the journal article.

SOURCE:

This study was led by Gokul Parameswaran, BM BCh, of Case School of Medicine in Cleveland. It was published online on May 27 in JAMA Cardiology.

LIMITATIONS:

Researchers downscaled state-level CVD data, assuming uniform rates across all counties. They averaged county temperatures and may have missed certain local urban heat islands. Baseline CVD rates were kept fixed through 2050 without accounting for future medical advances or changes in disease patterns.

DISCLOSURES:

No specific funding source was reported for the study. One author reported receiving grants from the National Institutes of Health and consultant fees from Novo Nordisk and Bayer.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.