Triple-digit heat exposure may increase odds of atrial fibrillation
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Key takeaways:
- Elevated ambient temperature was linked to higher odds of experiencing an AF episode.
- Fewer AF episodes occurred in the early morning vs. working hours.
- More events occurred during weekdays vs. the weekend.
CHICAGO — Rising outside temperature is associated with increased likelihood for experiencing an episode of atrial fibrillation as detected by implanted cardiac devices, according to new research.
Additionally, fewer AF events were observed during the early morning hours and on Saturday and Sunday compared with working hours and on weekdays, according to data presented at the American Heart Association Scientific Sessions.
“We have known for a while that increase in temperature is associated with CV outcomes, and there are many studies that showed increase in risk for death and heart attacks, but the studies that were done on arrhythmia did not utilize what is actually a very good way to measure arrhythmia, implanted devices,” Barrak Alahmad, MD, PhD, MPH, research fellow in environmental health at Harvard T.H. Chan School of Public Health, told Healio. “We only found a handful of studies. Some of them were done in Massachusetts. Another was done in London. But these were small studies that involved somewhere between 10 patients to 600 patients and they were also geographically limited. ... That’s why we thought it’s a good idea to look at implanted devices across a cohort of patients all across the U.S.”
The researchers used an industry surveillance registry (Medtronic) to identify U.S. patients who underwent an implantable cardioverter defibrillator or cardiac resynchronization therapy device implantation from 2016 to 2023.
For each identified patient, the researchers evaluated data on first AF episode detected on the device and matched it with hourly ambient temperature recordings from the nearest weather station to the patient’s place of residence. Conditional logistic models were pooled to evaluate the dose-response relationship between outdoor heat and AF episodes, according to the presentation.
In total, 2,313 individuals with a first AF event were included in the analysis.
Alahmad and colleagues observed fewer AF episodes in the early morning hours from midnight to 7 a.m. compared with normal working hours — 8 a.m. to 5 p.m. (P < .001) — and fewer AF episodes over the weekend compared with weekdays (P < .001).
In addition, the pooled conditional logistic models, which were calculated across all U.S. regions, showed that compared with locally optimal temperatures — between 5°C and 8°C, or 41°F and 46.4°F — the likelihood for AF events increased with higher outdoor temperatures:
- (OR for AF at 39°C, or 102.2°F = 2.66; 95% Cl, 1.57-4.54);
- (OR for AF at 40°C, or 104°F = 2.87; 95% Cl, 1.57-5.22); and
- (OR for AF at 41°C, or 105.8°F = 3.09; 95% Cl, 1.58-6.01).
Moreover, adjusting for lagging temperature exposure and restricting to AF events lasting longer than 30 minutes did not improve the model’s predictive strength, according to the presentation.
“I’ve spent some time looking at guidance that we have from the American Heart Association, the American College of Cardiology and the European Society of Cardiology, and I did not see guidance for clinicians on how to handle this extreme heat issue for their heart disease patients and, more specifically, for arrhythmia patients and those with implanted devices,” Alahmad told Healio. “The study is not a direct tool to be used in clinical intervention. However, the least that we could do is to exercise precaution now and just communicate this message while we figure out what we should do. What kind of advice and what kind of clinical intervention we could do to prevent these arithmetic events.”
Reference:
- 100F temps may be linked to irregular heartbeat in those with implanted defibrillators. https://newsroom.heart.org/news/1000-f-temps-may-be-linked-to-irregular-heartbeat-in-those-with-implanted-defibrillators. Published Nov. 11, 2024. Accessed Nov. 14, 2024.
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Alahmad B, et al. Abstract MDP1723. Presented at: American Heart Association Scientific Sessions; Nov. 16-18, 2024; Chicago.
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