Heat Waves and Cold Waves Increase Risk of Heart Attacks and Cardiovascular Issues

A new analysis confirms that both extreme heat and extreme cold significantly increase the risk of heart attacks, strokes, and other cardiovascular events, with air pollution amplifying these dangers.

According to findings presented at the European Society of Cardiology’s Preventive Cardiology 2026 congress in Ljubljana, Slovenia, researchers from the Medical University of Bialystok in Poland analyzed over eight million residents in Eastern Poland between 2011 and 2020. Their study, part of the Polish Smog EP-PARTICLES cohort, found that heatwaves and coldwaves were both associated with significant increases in major adverse cardiovascular and cerebrovascular events (MACCE), including cardiovascular death, ST-segment elevation myocardial infarction, and ischemic stroke.

The data showed 573,538 MACCE events, 377,373 cardiovascular deaths, and 831,246 all-cause deaths recorded over the study period. While both temperature extremes raised risk, the patterns differed: heat-related cardiovascular strain often involved increased heart demand, dehydration, and blood clotting, whereas cold exposure was linked to vasoconstriction and elevated blood pressure, which can trigger cardiac events in vulnerable individuals.

Critically, air pollution worsened outcomes in both scenarios. Exposure to fine particulate matter (PM2.5) over hours to weeks was found to increase the likelihood of heart attacks, strokes, arrhythmias, and worsening heart failure, particularly when combined with temperature extremes. The researchers noted that these effects were more pronounced in women and younger individuals, highlighting a need for targeted public health strategies.

Supporting evidence from the U.S. Centers for Disease Control and Prevention (CDC) reinforces these findings, advising that patients with cardiovascular disease should monitor daily heat risk and air quality indices. The CDC recommends creating personalized heat action plans, checking local air quality when the AQI exceeds 100, and reviewing medications — such as certain antihypertensives — that may increase heat sensitivity during warmer months.

A separate study cited by Mount Sinai Health System in March 2026 estimated that cold-related cardiovascular deaths account for approximately 40,000 annual fatalities in the United States, underscoring that while heat waves receive more public attention, cold weather remains a leading contributor to temperature-related heart disease mortality.

Experts urge coordinated efforts to address both climate-driven temperature extremes and air pollution as interconnected threats to cardiovascular health. Preventive measures include staying hydrated during heat, avoiding overexertion, using air filtration indoors during high pollution days, and following medical guidance tailored to seasonal risks.

As climate variability increases the frequency and intensity of both heatwaves and coldwaves, integrating environmental monitoring into cardiovascular care may become essential for reducing preventable illness and death.