Heatwaves and Heart Attacks : Understanding the Elevated Risk

New research has recently underscored the alarming connection between extreme heat and an increased risk of fatal heart attacks. The study, published in the American Heart Association’s journal Circulation, suggests that cardiovascular deaths from extreme heat in the United States alone could surge by 162 percent by the mid-century, assuming effective greenhouse gas emission reduction policies are in place. In a scenario with minimal emission reduction efforts, this risk could even spike by 233 percent between 2036 and 2065. The impact is projected to be more pronounced among older adults and non-Hispanic Black adults, emphasizing the potential exacerbation of existing health disparities.^(1,2)

This concerning trend aligns with previous studies demonstrating the cardiovascular effects of extreme temperatures. In a separate Circulation study focused on the Chinese province of Jiangsu, researchers discovered a significant association between heart attack deaths and extreme temperatures, both hot and cold, as well as high levels of particulate matter pollution. As climate change continues, these findings underscore the urgent need for comprehensive strategies to mitigate its impact on public health. Addressing climate change is not only an environmental imperative but also a crucial step in safeguarding cardiovascular health and promoting health equity.⁽³⁾

The nexus between greenhouse gas emissions, air pollution, and their profound impacts on health has become increasingly evident. Greenhouse gases, primarily carbon dioxide, contribute to climate change, creating a cascade of health challenges. Concurrently, air pollution, characterized by particulate matter (PM), poses its own set of dire consequences. The Centers for Disease Control and Prevention define PM as airborne particles originating from sources like smoke, dust, and dirt.⁽⁴⁾

In fact, the month of July in the year 2023 marked a significant milestone, becoming the hottest month in 174 years according to the National Oceanic and Atmospheric Administration (NOAA).⁽⁵⁾ Wildfires in Canada further aggravated pollution levels across the U.S., emphasizing the interconnectedness of climate change and air quality.

Dr. Robert Brook, an American Heart Association volunteer and expert on air pollution, highlighted the alarming statistics.⁽⁶⁾ Fine particulate matter air pollution (PM2.5) alone is responsible for over six million deaths annually. Dr. Brook emphasized that the recent study on extreme heat days reveals a broader dimension of harm caused by air pollutants, extending beyond PM2.5.⁽⁷⁾ As greenhouse gas emissions intensify, amplifying the frequency of extreme heat events, the threat to well-being becomes even more pronounced.

This intersection of environmental factors not only demands urgent mitigation strategies, but also underscores the need for comprehensive public health measures to address the multifaceted impact of climate change on human health.

While the dangers of air pollution are commonly associated with respiratory health, there is a growing acknowledgment among healthcare providers that its insidious effects extend to the heart. The intricate interplay of the body’s vital organs means that what harms one can significantly impact another. According to many expert cardiologists, PM2.5 particles, minuscule airborne particles, pose a dual risk by infiltrating deep into the lungs and entering the bloodstream.

Once within the body, these particles trigger inflammation and oxidative stress, culminating in damage to blood vessels and the heart. Experts have further emphasized that exposure to PM2.5 is linked to the development and progression of atherosclerosis—the accumulation of plaque in arteries, heightening the risk of heart attacks. Days marked by high pollution levels, where PM2.5 exceeds recommended thresholds, significantly elevate these risks.^(8,9)

To empower individuals in assessing their risk, platforms like AirNow.gov provide real-time air quality data by zip code, enabling people to make informed decisions, especially on days when PM2.5 levels pose a substantial threat to heart health.⁽¹⁰⁾  This underscores the importance of proactive measures and awareness to mitigate the pervasive impact of air pollution on cardiovascular well-being.

Extreme temperatures and heightened air pollution levels disproportionately jeopardize specific demographic groups, elevating their vulnerability to fatal heart attacks. This at-risk population encompasses individuals with pre-existing heart conditions like coronary artery disease and hypertension, non-Hispanic Black adults, older adults, pregnant individuals, and those with diabetes. The October 2023 Circulation study sheds light on the augmented risks faced by older adults and Black individuals in the United States, highlighting the intricate interplay of medical conditions, environmental factors, and racial disparities. ^(11,1)

According to the lead author of the study, factors such as limited access to air conditioning, reduced tree cover, and the exacerbation of the ‘urban heat island effect’ contribute to the heightened vulnerability of Black residents. The urban heat island effect manifests as built-up areas experiencing more significant temperature increases than their less-developed surroundings. Furthermore, living conditions, including social isolation prevalent among certain older adults, have been linked to an increased likelihood of death during extreme heat events.

This profound intersection of environmental, medical, and socio-economic factors further increase the urgent need for targeted interventions, policies, and community-based initiatives to safeguard the health of these vulnerable populations amidst the escalating challenges posed by climate change.

Extreme temperatures, whether soaring heat or biting cold, pose a tangible threat to heart health, with researchers and cardiologists concurring on the heightened risk of fatal heart attacks. However, the definition of what constitutes extreme heat or cold lacks a universal standard, often depending on geographical location and local conditions.

There is a pressing need to acknowledge the adverse effects of extreme weather, including high air pollution, on heart health. Planning ahead to mitigate these stresses becomes imperative.

While there is no one-size-fits-all definition, a general baseline can be established. Extremely hot weather involves temperatures significantly surpassing the area’s average for a given season, consistently exceeding the 90th percentile. Conversely, extremely cold weather entails temperatures significantly below the area’s average, consistently falling below the 10th percentile.

This nuanced understanding of extreme temperatures is crucial for individuals and healthcare providers to develop informed strategies to minimize the cardiovascular risks associated with fluctuating weather conditions.

Physiological responses to extreme heat, such as sweating and blood vessel dilation, are the body’s adaptive mechanisms to survive. However, this adaptation can intensify the heart’s workload, particularly during activities that demand high cardiovascular output. Even routine tasks become more taxing in extreme heat, elevating the risk of a cardiovascular event. Dehydration, a common consequence of hotter temperatures, further amplifies this risk. Dehydration can also induce syncope, leading to unconsciousness due to inadequate blood flow to the brain. Moreover, reduced blood flow to the heart can further increase the likelihood of blood clot formation, potentially triggering a heart attack.

Experts have emphasized the importance of knowing one’s own limits during extreme weather and adopting a cautious approach to physical activities. To stay protected, doctors recommend staying hydrated by drinking plenty of water and seeking shade or air-conditioned spaces to avoid overheating. Modifying outdoor workouts, such as reducing speed and distance, is also advised in order to adapt to extreme conditions. Listening to your body, dressing in loose, lightweight clothing, and avoiding peak heat hours (10 a.m. to 4 p.m.) further contribute to a safer experience.

Therefore, understanding the heightened risk of heart attacks during heatwaves is crucial for proactive health management. By following expert-recommended precautions, individuals can navigate extreme temperatures with greater safety and reduce the risk of cardiovascular events. Remaining vigilant and adopting preventive measures can empower individuals to safeguard their heart health amidst the rising threat of extreme heat and its impact on cardiovascular well-being.

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