For people with coronary heart disease, beta blockers can improve survival and quality of life, while aspirin and other antiplatelet medications can reduce the risk of a heart attack.
But those protections could backfire during hot weather, when heart attacks are more likely. A new study found that, among people suffering nonfatal heart attacks associated with hot weather, an outsize portion are taking these heart drugs.
The study appears online in Nature Cardiovascular Research.
“Patients taking these two medications have higher risk,” said Kai Chen, PhD, an assistant professor in the department of epidemiology (environmental health) at the Yale School of Public Health and first author of the study. “During heat waves, they should really take precautions.”
Using a registry, the authors looked at 2,494 cases in which individuals experienced a nonfatal heart attack in Augsburg, Germany, during hot months (May through September) between 2001 and 2014.
In previous research, they had shown that exposure to either heat or cold made heart attacks more likely, and they calculated that heat-related heart attack rates would rise once the planet has warmed by 2 to 3 degrees Celsius over preindustrial times.
The current study built on that research by examining patients’ medication use prior to their heart attack.
It turned out that users of beta blockers or antiplatelet medications were likelier to have heart attacks during the hottest days compared with other days. Antiplatelet medication use was associated with a 63% increase in risk, and beta blockers with a 65% increase. People taking both drugs had a 75% higher risk. Nonusers of those medications were not more likely to have a heart attack on hot days.
The study doesn’t prove that these medications caused the heart attacks, nor that they make people more vulnerable to heart attack. Although it’s possible that they did increase the risk of heart attacks triggered by hot weather, it’s also possible that patients’ underlying heart disease explains both the prescriptions and the higher susceptibility to heart attack during hot weather.
Still, there is at least one clue that these two medication types may render people more vulnerable: For the most part, other heart medications didn’t show a connection to heat-related heart attacks. (An exception was statins. When taken by younger people, statins were associated with an over threefold risk of a heart attack on hot days.)
“We hypothesize that some of the medications may make it hard to regulate body temperature,” Chen said. He plans to try to untangle these relationships in future studies.