Exposure to cold weather significantly increases the risk of heart attacks, according to a recent study published in the Journal of the American College of Cardiology and presented at the European Society of Cardiology Congress (ESC 2024).
The research highlights the importance of understanding how colder temperatures, potentially worsened by global climate changes, can impact heart health.
The study, led by Dr. Wenli Ni, a postdoctoral research fellow at Harvard University, found that hospital admissions for heart attacks, also known as myocardial infarctions (MI), tend to rise after exposure to lower air temperatures and during cold spells.
A cold spell was defined in the study as at least two consecutive days where the average daily temperature was colder than the 10th percentile of recorded temperatures over the study period.
“This nationwide study reveals that short-term exposures to lower air temperature and cold spells are associated with an increased risk of myocardial infarction hospitalization after 2 to 6 days, suggesting that individuals may be particularly vulnerable to acute cardiac events during periods of cold stress,” said Dr. Ni.
Heart attacks happen when blood flow to a part of the heart is blocked, usually by a blood clot, preventing oxygen from reaching the heart muscle.
This blockage can cause serious damage or death to the affected part of the heart. Previous research has shown that cold temperatures can place a greater burden on the cardiovascular system than hot temperatures, but this study adds new insight by focusing on the delayed effects of cold exposure.
The research was conducted in Sweden, a country known for its cold climate and frequent cold spells.
The study tracked 120,380 individuals from the SWEDEHEART registry, examining how short-term exposure to lower air temperatures and cold spells influenced the risk of heart attack hospital admissions during Sweden’s cold season, from October to March, between 2005 and 2019.
The results showed that exposure to cold air was linked to an increased risk of heart attacks, including both types known as NSTEMI and STEMI, two to six days after the cold exposure. Interestingly, the study also found that the risk of heart attacks actually decreased during the first one to two days after a cold spell.
The researchers suggest this temporary protective effect might be due to changes in behavior during cold weather, such as staying indoors or delaying medical care because of disruptions caused by the weather.
However, these behaviors might only delay the onset of heart attacks, leading to an increase in hospitalizations a few days later.
“This temporal pattern may indicate a delayed onset of cold-related impacts on MI risk, aligning with prior research underscoring delayed cardiovascular effects of cold exposure,” Dr. Ni explained.
Understanding this delay could be crucial for developing preventive measures to protect people during cold weather.
The study also found that the effects of cold weather on heart attacks were similar for both first-time and recurrent heart attacks, although the difference between these two groups was not statistically significant.
In an editorial comment accompanying the study, Dr. Kai Chen from Yale School of Public Health and Dr. Khurram Nasir from Houston Methodist emphasized the need to reconsider how health care professionals address the relationship between environmental factors and heart health.
They stressed the importance of preparing health care systems to manage the challenges posed by increasingly unpredictable weather patterns, which could impact cardiovascular health in the future.
By better understanding the link between cold weather and heart attacks, health care providers can develop targeted strategies to protect vulnerable populations, especially during cold spells, and ensure that health systems are equipped to handle these risks.
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