As summer temperatures rise across the United States, the American Heart Association is alerting the public that extreme heat poses a serious threat to cardiovascular health. According to the National Weather Service, extreme heat is the leading weather-related cause of death in the country, surpassing more visually dramatic disasters like hurricanes and tornadoes. A report in the Journal of the American Medical Association found that more than 2,300 people died from heat exposure in 2023, and research published in the American Heart Association’s journal Circulation projects that heat-related cardiovascular deaths could more than double in the coming decades.
“Heat forces the heart to work harder,” said Dr. Manesh R. Patel, volunteer president of the American Heart Association and chief of the division of cardiology at Duke Health. “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.” The body’s natural cooling mechanism—sweating—leads to fluid loss and dehydration, while the heart must pump more blood to regulate temperature, placing significant stress on the cardiovascular system.
To reduce risk, the American Heart Association recommends limiting outdoor activity between noon and 3 p.m., when temperatures peak, and wearing lightweight, light-colored clothing along with a hat and sunglasses. Staying hydrated is crucial: drinking water before, during, and after time outdoors, while avoiding alcohol and caffeinated drinks that can contribute to dehydration. Taking breaks in the shade or a cool indoor space allows the body to recover.
Recognizing warning signs can save lives. Heat exhaustion symptoms include headache, cool pale clammy skin, fast but weak pulse, dizziness, weakness, muscle cramps, and nausea. If these occur, move to a cooler place, cool down with cold water, and rehydrate; medical attention may be necessary. Heat stroke is a medical emergency—call 9-1-1 if body temperature exceeds 103°F, skin is hot and red, pulse is rapid and strong, or there is confusion or loss of consciousness.
Physical activity remains important for heart health, but should be shifted to cooler times of day or moved indoors to air-conditioned spaces. The American Heart Association offers more tips on staying heart-healthy in the heat at heart.org. For additional resources, including an infographic on hydration, visit the American Heart Association's hydration page.
