Cardiovascular disease (CVD) remains the leading cause of death worldwide, with approximately one in three deaths attributable to CVD. According to a 2024 World Heart Federation report, more than 20 million deaths were due to CVD in 2021.
Despite significant advances in heart disease prevention, treatment and intervention, climate change threatens to reverse these gains.
NASA has found that over the past century, the Earth's average temperature has risen by more than 2 degrees Fahrenheit, causing long-term changes in weather patterns, disturbances to ecosystems, and rising sea levels. Amazingly, the hottest 10 years on record have all occurred in the past decade.
Climate change and cardiovascular health
A new study conducted by researchers at Beth Israel Deaconess Medical Center (BIDMC) delves deeper into the relationship between environmental stresses related to climate change and cardiovascular disease. The research team conducted a systematic review of 492 observational studies to investigate this important question.
Findings revealed a strong association between extreme temperatures, hurricanes, and increased CVD mortality and morbidity.
Vulnerable populations, including seniors, racial and ethnic minorities, and low-income people, have been disproportionately affected.
Effects of Environmental Stress
“Climate change is already affecting our cardiovascular health,” said Dhruv S. Kazi, associate director of the Richard A. and Susan F. Smith Center for Outcomes Research at BIDMC and corresponding author of the study.
“Exposure to extreme heat can have adverse effects on heart rate and blood pressure, ozone and wildfire smog can cause systemic inflammation, and experiencing a natural disaster can cause mental stress.”
“Hurricanes and floods may disrupt the delivery of health services due to power outages and supply chain disruptions. In the longer term, climate change is projected to reduce agricultural productivity and the nutritional value of the food supply, which may also have negative effects on cardiovascular health.”
The research team examined approximately 21,000 peer-reviewed studies published between 1970 and 2023.
These studies assessed associations between acute cardiovascular events, CVD mortality, and health care utilization and a range of climate change-related phenomena, including extreme temperatures, wildfires, air pollution, ground-level ozone, extreme weather events, sea-level rise, saltwater intrusion, and climate-related migration.
Extreme weather events linked to risk of cardiovascular disease
Of the 492 global observational studies included in the review, 182 investigated extreme temperatures, 210 focused on the effects of ground-level ozone, 45 looked at wildfire smoke, and 63 investigated extreme weather events such as hurricanes, dust storms, and droughts.
These studies included 30 high-income countries, 17 middle-income countries, and one low-income country.
The researchers found that exposure to extreme temperatures was strongly associated with increased cardiovascular disease incidence and mortality, and that the effects varied by temperature and duration of exposure.
Extreme weather events such as tropical storms, hurricanes, floods and landslides are also associated with an increased risk of cardiovascular disease, often for months or even years after the extreme weather event.
One study of Hurricane Sandy, which caused nearly $20 billion in damages in New York City alone in 2012, showed that the risk of death from cardiovascular disease remained elevated for up to 12 months after the storm.
Addressing knowledge gaps
The researchers also found that there are significant gaps in knowledge about the impact of climate change on cardiovascular disease risk in low-income countries.
Only one study was conducted in a low-income country, and only five were based in Africa, an area where climate change is expected to have disproportionate effects.
“Although there is a paucity of data on outcomes in low-income countries, our study shows that several environmental stressors, which are already increasing in frequency and intensity with climate change, are associated with increased cardiovascular disease risk,” noted lead author Mary B. Rice, M.D., a pulmonologist and critical care physician at BIDMC.
Recommendations for health systems
These findings suggest that clinicians should be aware of climate-related cardiovascular risks in their communities, whether related to extreme temperatures, wildfire smoke, or extreme weather events.
For example, in areas prone to hurricanes or flooding, clinicians should help develop emergency response plans to ensure patients have uninterrupted access to medications and medical care if needed.
Health systems should also assess the resilience of their infrastructure to climate change.
“Climate change is already adversely affecting cardiovascular health in the United States and around the world,” the researchers concluded. “Urgent action is needed to reduce cardiovascular risks associated with climate change, especially among the most vulnerable populations.”
The study is published in JAMA Cardiology.
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