Heatwaves Pose Severe Risk to Cardiovascular Health in Greece, Experts Warn

As summer temperatures rise, the Greek Cardiology Society (GCS) warns of a significant increase in cardiovascular admissions and deaths, highlighting the scientifically established link between heat and heart disease. This phenomenon affects millions in Greece, with the GCS presenting new data and protection guidelines for individuals with pre-existing heart conditions.

The GCS emphasizes that heatwaves are not merely uncomfortable but proven risk factors with measurable consequences for cardiovascular health. A meta-analysis of 54 epidemiological studies across 20 countries, published in The Lancet Planetary Health, revealed that heatwaves elevate cardiovascular mortality by about 15% compared to periods with normal temperatures. The danger escalates with the duration of the heatwave; a study in BMC Public Health indicated that when temperatures exceed 35°C for four consecutive days, cardiovascular mortality increases by 10%, potentially reaching up to 51% from the fifth day onwards.

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Heatwaves increase cardiovascular mortality by about 15% compared to periods of normal temperatures.

Older adults, particularly those over 65, face heightened risks. For this age group, prolonged heatwaves of five days or more can lead to a 24% increase in mortality, significantly higher than the 18% increase observed in the general population. This vulnerability underscores the need for targeted protective measures for the elderly during extreme heat events.

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When the maximum temperature exceeds 35°C for four consecutive days, cardiovascular mortality increases by 10%, and from the fifth day, it can reach up to 51%.

Compounding the effects of heat is air pollution, which worsens during summer months. High temperatures promote the formation of tropospheric ozone and increase concentrations of fine particulate matter (PM2.5). Studies in the Journal of the American College of Cardiology show that PM2.5 exposure triggers vascular inflammation, endothelial dysfunction, and oxidative stress, accelerating atherosclerosis and increasing the risk of heart attack, stroke, and heart failure. In urban centers like those in Greece, the combination of heat and pollution, exacerbated by traffic and wildfires, creates a synergistic effect that significantly multiplies the risk for cardiovascular patients.

When the body overheats, it increases blood flow to the skin to dissipate heat, placing a strain on the heart, which must pump more blood at a faster rate, often leading to a drop in blood pressure. Dehydration from sweating further depletes fluids and electrolytes, potentially destabilizing heart rhythm and interfering with medications like diuretics and antiarrhythmics. Certain heart medications, such as beta-blockers, can hinder the compensatory increase in heart rate, while diuretics can worsen dehydration, and antihypertensive drugs may also be affected, adding complexity to managing cardiovascular health during heatwaves.

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Exposure to PM2.5 causes vascular wall inflammation, endothelial dysfunction, and oxidative stress, mechanisms that accelerate atherosclerosis and increase the risk of heart attack, stroke, and heart failure.