As summer temperatures soar across the United States, the American Heart Association (AHA) is issuing a stark warning: extreme heat is not just uncomfortable—it 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 even hurricanes and tornadoes in annual fatalities.
A report published in the Journal of the American Medical Association revealed that more than 2,300 people died from heat exposure in the U.S. in 2023. Further, research in the AHA journal Circulation projects that heat-related cardiovascular deaths could more than double in the coming decades, underscoring the growing danger as global temperatures rise.
“Heat forces the heart to work harder,” said Dr. Manesh R. Patel, volunteer president of the American Heart Association and chief 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 physiological response to heat involves sweating to cool the body, which can lead to fluid loss and dehydration. Simultaneously, the heart must pump more blood to regulate body temperature, placing significant stress on the cardiovascular system. This strain can trigger adverse events, particularly in individuals with pre-existing heart conditions.
To mitigate these risks, the AHA recommends several precautionary measures. Avoiding outdoor activity between noon and 3 p.m., when temperatures peak, is advised. Wearing lightweight, light-colored clothing, a hat, and sunglasses, along with applying sunscreen, can help. Staying hydrated by drinking water before, during, and after time outdoors is crucial, while alcohol and caffeinated beverages should be avoided as they can contribute to dehydration.
Taking breaks in the shade or a cool indoor space allows the body to recover. Recognizing the warning signs of heat-related illness can be life-saving. Symptoms of heat exhaustion include headache, cool and clammy skin, a fast but weak pulse, dizziness or fainting, weakness or muscle cramps, and nausea or vomiting. If these occur, individuals should stop physical activity, move to a cooler place, cool down with cold water, and rehydrate. Medical attention may be necessary.
Heat stroke is a medical emergency requiring immediate action. Signs include a body temperature above 103°F, hot and red skin, a rapid and strong pulse, confusion, headache, loss of consciousness, or nausea. If these are observed, call 9-1-1 without delay.
Despite the risks, physical activity remains essential for heart health, even in summer. The AHA suggests shifting exercise to early morning or evening hours, or moving workouts indoors to air-conditioned spaces such as gyms or community centers. Activities like walking, swimming, biking, or even gardening count toward staying active.
For more information on staying heart-healthy in the heat, visit heart.org. Additional resources, including infographics on hydration, are available through the AHA's official channels.
