The Heart Suffers in Heat Waves... Myocardial Infarction Is More Dangerous in Summer [Kok! Health]

80% of Patients Are Men, Highest in Their 60s

Seek Emergency Care for "Tearing Chest Pain" or Cold Sweats

Two-Hour Golden Window—Delays Can Lead to Heart Muscle Necrosis

Heat waves do more than just bring intense heat—they also put a strain on the heart and blood vessels. While many people associate myocardial infarction with the cold winter months, data from the past five years tells a different story. There are actually more cases in the summer than in winter. This is why it is especially important to pay attention to heart health as the early summer heat intensifies.

According to statistics from the Health Insurance Review and Assessment Service, from December 2020 to August 2025, the number of patients visiting the hospital for acute myocardial infarction was higher in the summer months (June to August) than in the winter months (December to February). Over the five-year period, the cumulative number of patients in the summer reached 502,086, compared to 488,506 in winter—an increase of more than 13,500 during the summer. Around 80% of all patients were men, with the highest proportion found among men in their 60s.

Image depicting a man experiencing symptoms of a myocardial infarction. Photo by Getty Images Korea

Acute myocardial infarction is a medical emergency in which a blood clot (thrombus) blocks a coronary artery that supplies blood to the heart muscle, causing the heart tissue to die. Cholesterol and inflammation accumulate on the artery wall, forming an atherosclerotic plaque. When this plaque ruptures, a blood clot forms, and the resulting thrombus blocks the coronary artery, leading to the onset of the condition.

There are two main reasons for the increase in cases during the summer: dehydration and excessive air conditioning. Dehydration is the primary trigger. As sweat causes fluid loss, plasma volume decreases and the blood becomes more viscous. This results in a relative concentration of red blood cells and platelets, making the blood more prone to clot formation. At the same time, the heart rate increases to compensate for the reduced blood volume, which further burdens the heart. This is why it is essential to stay hydrated during the summer.

Air conditioning is another factor. Going directly from sweltering heat above 30 degrees Celsius into a strongly air-conditioned indoor space causes blood vessels, which have expanded to release heat, to constrict rapidly. This sudden change sharply increases the pressure on the heart, making atherosclerotic plaques inside the blood vessels more likely to rupture. It is recommended to keep the temperature difference between indoors and outdoors within about 5 degrees Celsius, and to wear a light outer layer to minimize abrupt changes in body temperature.

The most common warning sign is chest pain. This typically manifests as an intense pain described as "tearing" or "like being stepped on by an elephant," which is different from any previous experience. The pain often does not subside even after 30 minutes of rest, and may radiate to the inside of the left arm or the tip of the jaw. Cold sweats often accompany these symptoms.

However, not all patients experience chest pain. Elderly individuals and those with diabetes may have silent myocardial infarction without chest pain. Instead, symptoms such as sudden shortness of breath, extreme fatigue, cold sweats, nausea, or a feeling of tightness in the upper abdomen may appear first. In such cases, an accurate diagnosis through electrocardiogram and blood tests is necessary.

Treatment is a race against time. While medications called thrombolytics can dissolve blood clots in the coronary arteries, procedures that physically reopen blocked arteries are more effective. The most common intervention is percutaneous coronary intervention, in which a balloon or metal mesh stent is used to widen the artery. Generally, the blocked artery must be reopened within two hours to minimize heart muscle damage.

Clinical Yeop Lim, Professor of Cardiology at Korea University Ansan Hospital. Korea University Ansan Hospital

Clinical Professor Youngup Lim, Department of Cardiology at Korea University Ansan Hospital, said, "For acute myocardial infarction, the survival rate and prognosis vary greatly depending on how quickly the blocked artery is reopened after onset. If symptoms occur, it is crucial to receive a prompt diagnosis in the emergency room and, if necessary, to proceed without delay to percutaneous coronary intervention." He added, "Middle-aged and older adults with underlying conditions such as hypertension, diabetes, or hyperlipidemia, or those who smoke, should avoid strenuous outdoor activity during heat waves."

This content was produced with the assistance of AI translation services.