A heat wave with daily highs exceeding 30 degrees Celsius continues across the country. Medical experts warn that such weather, which causes frequent sweating and dehydration, makes people more vulnerable to acute myocardial infarction, requiring caution.
It is easy to assume that cardiovascular diseases such as myocardial infarction should only be guarded against in winter, when falling temperatures cause blood vessels to contract. In reality, however, the risk is higher in summer. The elderly and patients with chronic conditions need to be especially careful.
According to statistics from the Health Insurance Review and Assessment Service covering December 2020 to August 2025, more patients visited hospitals for acute myocardial infarction in summer (June to August) than in winter (December to February), the agency said Wednesday.
Looking at the cumulative number of patients over the five years, summer recorded 502,086, more than 13,500 higher than the 488,506 in winter. In particular, about 80% of all patients were male, with men in their 60s accounting for the largest share.
Acute myocardial infarction is a serious emergency disease in which the coronary artery supplying blood to the heart muscle is suddenly blocked by a thrombus (blood clot), causing the heart muscle to die. When cholesterol and inflammation accumulate on the blood vessel wall, an atherosclerotic plaque forms. When this plaque ruptures, a thrombus develops and blocks the coronary artery, causing the condition.
The causes of summer heart attacks include "dehydration" and "excessive air conditioning." When heavy sweating rapidly drains the body of water, blood viscosity increases, creating an environment in which thrombi are likely to form.
Excessive air conditioning can also be a problem. When someone moves suddenly from sweltering heat above 30 degrees into an indoor space with strong air conditioning, the blood vessels that had expanded to release heat contract in an instant. In this process, the pressure placed on the heart surges, which can leave the atherosclerotic plaque in the blood vessels prone to rupture, requiring caution. It is advisable to keep the difference between indoor and outdoor temperatures at around 5 degrees and to carry a light outer layer to prevent sudden changes in body temperature.
A representative warning sign is severe chest pain unlike any experienced before, as if the chest is being torn or stepped on by an elephant. It may not subside even after 30 minutes of rest, or may be accompanied by radiating pain extending to the inner left arm or the tip of the chin, along with cold sweats.
In addition, the elderly and diabetic patients may experience asymptomatic heart attacks without chest pain. Symptoms such as sudden shortness of breath, extreme lethargy, cold sweats, nausea, or tightness in the upper abdomen can appear without chest pain. In such cases, accurate diagnosis through electrocardiogram tests and blood tests is necessary.
"With acute myocardial infarction, survival rates and prognosis vary greatly depending on how quickly the blocked blood vessel is reopened after onset," said Lim Sang-yup, a professor of cardiology at Korea University Ansan Hospital. "Immediately after symptoms occur, patients should be rapidly diagnosed in the emergency room and, if necessary, undergo coronary intervention without delay."
He added, "Middle-aged and older people who have underlying conditions such as high blood pressure, diabetes, or hyperlipidemia, or who smoke, should avoid strenuous outdoor activity during a heat wave."
