NEW YORK CITY — The American Heart Association published a scientific statement in 2026 identifying extreme heat and cold as cardiovascular risks. The statement, "Nonoptimal Temperature and Cardiovascular Health," appeared in the journal Circulation.

Extreme temperatures can trigger heart attacks, strokes, heart failure, and sudden cardiac death. Historically, cold weather has caused more cardiovascular deaths than heat, attributed to the more frequent occurrence of cold days.

However, the frequency, intensity, and duration of extreme heat events are increasing. 2024 was recorded as the hottest year since the National Oceanic and Atmospheric Administration began record-keeping in 1880. Arnab Ghosh, an associate professor of medicine at Weill Cornell Medicine and an internist at NewYork-Presbyterian/Weill Cornell Medical Center, led the development of the policy section of the American Heart Association report. "As heatwaves increase, we need coordinated action in research, clinical practice and policy to understand how we can keep people safe," Ghosh said. "Heat is a problem now; we can't wait."

The human body cools itself in hot weather through vasodilation and increased sweating, which lower blood pressure and reduce body fluid levels. The heart compensates for these changes by beating faster and pumping harder. This increased cardiac workload can pose dangers for individuals with preexisting cardiovascular disease.

Older adults face elevated cardiovascular risks from extreme heat because aging impairs the body's ability to regulate temperature. Common heart medications, including diuretics, blood pressure medications like lisinopril and losartan, calcium channel blockers, statins, and antiarrhythmics, can also increase sensitivity to sunlight and heat. Diuretics and similar heart medications cause patients to lose additional water.

Miroslaw Sochanski, a physician at CommonSpirit Health, said, "When the heat goes up, usually our body temperature goes up and then it tends to make our heart work harder, and the heart speeds up, and then it starts to have a cascade of problems if we're not conditioned." He added, "Hydration means drinking water with some electrolytes." The human body loses both water and salt through sweat during heat exposure. Beverages with high caffeine or sugar content can exacerbate dehydration.

Ghosh said, "We need a fundamentally different system that still delivers the same health benefits but is also good for the planet."