A recent study published on June 10 in the Journal of Arrhythmia highlights that disordered sleep may adversely affect heart health more during the day than at night. Dr. Reena Mehra, a sleep medicine specialist at UW Medicine, noted that these findings could enhance treatment approaches for atrial fibrillation, a condition affecting approximately 1 in 20 adults in the United States, which increases the risk of blood clots, stroke, and heart failure.
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Sleep apnea leads to repeated interruptions in breathing during sleep, causing drops in oxygen levels, increases in carbon dioxide, and elevated blood pressure. Over time, these factors heighten the risk of developing heart conditions. Individuals with sleep apnea face a two- to five-fold higher likelihood of experiencing atrial fibrillation, characterized by an irregular and often rapid heart rhythm.
This study is part of the SAFEBEAT research project, which investigates the connections between sleep apnea and atrial fibrillation. It involved a cohort of 150 patients diagnosed with atrial fibrillation. The research team employed electrocardiography to measure heart rate variability and tested participants for sleep apnea, treating affected individuals using continuous positive airway pressure (CPAP) machines.
Contrary to expectations that heart rate variability would show greater abnormalities during sleep, Mehra's analysis revealed more substantial alterations during wakefulness. She suggested this could indicate that the cumulative effects of sleep apnea on heart function may not peak until daytime or that these effects are amplified due to daytime activities.
These insights could prompt changes in the diagnostic and treatment strategies for atrial fibrillation. Daytime monitoring may become crucial for these patients, and medication timing might be adjusted for optimal impact during the day.
Following treatment with CPAP machines, patients reported improved sleep apnea symptoms and normalized heart rate variability, indicating that addressing sleep apnea is a potentially vital aspect of managing atrial fibrillation.
As a next step, Mehra is initiating a randomized controlled trial to evaluate the effects of CPAP on atrial fibrillation and is exploring whether biochemical markers of sleep apnea and atrial fibrillation can be identified in the bloodstream. This study was backed by a grant from the National Institutes of Health, under the National Heart, Lung and Blood Institute (NCT02576587).