For people with coronary heart disease, beta-blockers improve survival and quality of life, and aspirin and other antiplatelet drugs reduce the risk of heart attack.
But these protective measures can backfire during hot weather, when heart attacks are more likely. A new study shows that some of the people who suffer non-fatal heart attacks related to hot weather take these heart drugs.
“Patients taking these two drugs are at increased risk,” said Kai Chen, assistant professor of epidemiology (environmental health) at the Yale School of Public Health and first author of the study. “During heat waves, they really need to take precautions.”
These precautions include cooling strategies such as using air conditioning or visiting a community cooling center.
External environmental factors such as air pollution and cold weather can trigger heart attacks. A growing body of evidence suggests that hot weather can do the same. But epidemiologists are still working to determine which groups of people are most vulnerable to environmental extremes.
Using the registry, the authors reviewed 2,494 cases of nonfatal heart attacks in Augsburg, Germany, during the hot months (May through September) between 2001 and 2014.
In previous research, they showed that heat or cold made heart attacks worse, and estimated that the number of heat-related heart attacks would increase as the planet warmed by 2-3 degrees Celsius.
The current study builds on that research by examining patients’ medication use prior to their heart attack.
They compared the temperature on the day of the heart attack with the same days of the week during the same month and analyzed the data to allow patients to self-manage. In other words, if a person had a heart attack on the third Thursday in June, the authors compared the effect of temperature on that day with the effect of temperature on other “control” Thursdays in June.
Two dangerous drugs
It is known that users of beta-blockers or antiplatelet drugs are more likely to have a heart attack on the hottest days compared to control days. Use of antiplatelet drugs was associated with a 63% increased risk, and beta-blockers with a 65% increased risk. Those who used both drugs had a 75% higher risk. People who do not use those drugs do not have heart attacks on hot days.
Research does not prove that these drugs cause heart attacks, nor does it make people more vulnerable to heart attacks. Although they may increase the risk of heart attacks due to hot weather, patients’ underlying heart conditions may explain both the prescriptions and the high susceptibility to heart attack in hot weather.
However, one sign suggests that drugs may be to blame.
When researchers compared younger patients (ages 25 to 59) with older ones (ages 60 to 74), they found that, as expected, the younger group was healthier and had lower rates of coronary heart disease. Younger patients taking beta-blockers and antiplatelet drugs were also more likely to have heat-related heart attacks than older patients, even though the elderly were more likely to have heart disease.
Another clue that these two types of drugs may make people more vulnerable: For the most part, other heart drugs have not been shown to be linked to heat-related heart attacks. (Statins were an exception. When taken by young adults, statins more than tripled the risk of heart attack on hot days.)
“We hypothesize that some medications make it harder to regulate body temperature,” Chen said. He plans to try to address these relationships in future research.
The results suggest that with climate change, heart attacks may become a greater risk for some people with cardiovascular disease.
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Kai Chen et al. Nature cardiovascular research (2022). DOI: 10.1038/s44161-022-00102-z
Presented by the Yale School of Public Health
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