For people with coronary heart disease, beta-blockers are important medications that can improve survival and quality of life. Likewise, aspirin and other antiplatelet drugs can reduce the risk of a heart attack.
However, those protections could backfire during hot-weather events, a time when heart attacks are already more likely. A new study published on August 1 in the journal Nature Cardiovascular Research found that, among people suffering non-fatal heart attacks associated with hot weather, an outsize portion are taking these heart medications.
“Patients taking these two medications have higher risk,” said Kai Chen, an assistant professor in the Yale School of Public Health Department of Epidemiology (Environmental Health) and first author of the study. “During heat waves, they should really take precautions.”
Those safety precautions include cooling strategies like using air conditioning or visiting a public cooling center.
Air pollution, cold weather, and other external environmental factors can trigger heart attacks. There is growing evidence to suggest that hot weather can do so, too. However, epidemiologists are still working to identify which groups of people are most vulnerable to these environmental extremes.
Using a registry, the researchers analyzed 2,494 cases in which individuals experienced a non-fatal heart attack in Augsburg, Germany during the hot-weather months (May through September) between 2001 and 2014.
They had already shown in previous research that exposure to either heat or cold made heart attacks more likely. They also calculated that heat-related heart-attack rates would rise once the planet has warmed by 2° to 3° Celsius (3.6° to 5.4° Fahrenheit).
Built on that research, the current study examined patients’ medication use prior to their heart attack.
They analyzed the data in a way that let patients serve as their own controls. This was done by comparing heat exposure on the day of the heart attack versus the same days of the week within the same month. That is, if a person had a heart attack on the third Thursday in June, the researchers compared their temperature exposure that day to their temperature exposure on other, “control” Thursdays in June.
Two medications tied to risk
It turned out that users of beta-blockers or antiplatelet medications were likelier to have heart attacks during the hottest days compared to control 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. Non-users of those medications were not more likely to have a heart attack on hot days.
Although it shows an association, the study doesn’t prove that these medications caused the heart attacks, nor that they make people more vulnerable to heart attacks. It’s possible that they did increase the risk of heart attacks triggered by hot weather, but it’s also possible that patients’ underlying heart disease explains both the prescriptions and the higher susceptibility to heart attack during hot weather.
Still, one clue does suggest the medications could be to blame.
When the scientists compared younger patients (25 to 59 years) to older ones (60 to 74 years), they found, as expected, that the younger ones were a healthier group, with lower rates of coronary heart disease. Yet younger patients taking beta-blockers and antiplatelet medications were more susceptible to heat-related heart attack than older patients, despite the older ones having more heart disease.
Another 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.
The results suggest that as climate change progresses, heart attacks might become a greater hazard to some people with cardiovascular disease.
Reference: “Triggering of myocardial infarction by heat exposure is modified by medication intake” by Kai Chen, Robert Dubrow, Susanne Breitner, Kathrin Wolf, Jakob Linseisen, Timo Schmitz, Margit Heier, Wolfgang von Scheidt, Bernhard Kuch, Christa Meisinger, Annette Peters, KORA Study Group and Alexandra Schneider, 1 August 2022, Nature Cardiovascular Research.
The study appears online in Nature Cardiovascular Research. It was funded by the German Foundation of Heart Research, the University of Augsburg, and the University Hospital of Augsburg, Germany.
Professor Robert Dubrow was a co-author and Alexandra Schneider of Germany’s Helmholtz Zentrum Munchen was last author. The other co-authors were Susanne Breitner, Kathrin Wolf, Margit Heier, and Annette Peters, all of the Helmholtz Zentrum München–German Research Center; Jakob Linseisen of Ludwig-Maximilians-Universität München and University Hospital Augsburg; Timo Schmitz, Wolfgang von Scheidt, and Christa Meisinger of University Hospital Augsburg; and Bernhard Kuch of Hospital of Nördlingen (Germany). Brietner and Peters are also affiliated with Ludwig-Maximilians-Universität München, Peters with German Research Center for Cardiovascular Research, and Heier with University Hospital Augsburg.