Extreme Heat Puts Heart Health at Risk, American Heart Association Warns

As summer heat intensifies across the U.S., the American Heart Association is warning that soaring temperatures don't just make people uncomfortable - they can put serious strain on the heart and increase the risk of life-threatening complications. Although tragic deaths from major disasters like hurricanes and tornados may get the most news coverage, extreme heat is actually the leading weather-related cause of death in the United States, according to the National Weather Service.

A report in the Journal of the American Medical Association found that more than 2,300 people died from heat exposure in the U.S. in 2023. Research published in the American Heart Association's journal Circulation projecting that heat-related cardiovascular deaths could more than double in the coming decades.

"Heat forces the heart to work harder," said Manesh R. Patel, M.D., FAHA, volunteer president of the American Heart Association and chief of the division of cardiology, chief of the division of pharmacology and vice president of Heart and Vascular Services for Duke Health, Durham, North Carolina. "When your body is trying to cool down, your heart rate increases and your blood vessels expand. For people with heart disease, and even those who are otherwise healthy, that added strain can become dangerous quickly."

When temperatures climb, the body sweats to cool itself which can lead to fluid loss and dehydration. At the same time, the heart must pump more blood to regulate body temperature. Together, these changes can put significant stress on the cardiovascular system.

The American Heart Association recommends taking simple but important steps to stay safe: avoid peak heat hours by limiting outdoor activity between noon and 3 p.m., when temperatures are typically at their highest; dress smart by choosing lightweight, light-colored clothing and wearing a hat and sunglasses, and using sunscreen to protect your skin; stay hydrated by drinking water before, during and after time outdoors, while avoiding alcohol and caffeinated drinks; and take breaks in the shade or a cool indoor space to give your body time to recover.

Knowing the warning signs can save lives. Heat exhaustion symptoms may include headache, cool pale clammy skin, fast but weak pulse, dizziness or fainting, weakness or muscle cramps, and nausea or vomiting. If you experience any of these symptoms, slow down physical activity, move to a cooler place, cool down immediately by dousing yourself with cold water, and re-hydrate. You may need to seek medical attention. Heat stroke is a medical emergency. Call 9-1-1 immediately if you notice body temperature above 103°F, hot red dry or damp skin, rapid strong pulse, confusion headache or loss of consciousness, or nausea.

Physical activity remains essential for heart health, even in the summer months. Try walking, swimming, biking, skating, building a backyard obstacle course or organizing a neighborhood soccer game. However, in the heat of summer it may be best to shift exercise to early morning or evening hours, when it's cooler, or move workouts indoors to air-conditioned spaces such as gyms or community centers. Learn more about staying heart-healthy in the heat at heart.org.