While it has long been understood that sleep apnea often underlies heart issues, the rate of the condition is still under-diagnosed in these patients, leaving their condition and its possible complications to worsen unchecked. Yet, the reason for the difficulty in reaching a sleep apnea diagnosis, especially in patients living with atrial fibrillation, has been a matter of debate. Now however, two separate peer-reviewed studies have revealed a common issue behind the diagnostic failure – the fact that the questionnaires currently in use are not identifying the sleep apnea patient in proper way.
Here we will take an in-depth look at each study in order to highlight the conclusions reached by the research teams.
Sleep apnea in ablation candidates with paroxysmal atrial fibrillation
The first study, reported in IJC Heart & Vasculature, set out to determine the prevalence, characteristics, and risk factors as well as type of sleep apnea most common in ablation candidates with paroxysmal atrial fibrillation.
The researchers recruited 579 patients with paroxysmal AF and utilized polygraphy for two nights at home to diagnose sleep apnea. These results were also compared against questionnaire results including, the Epworth Sleepiness Scale (ESS), STOP-Bang Questionnaire, and Berlin Questionnaire (BQ), which assessed the degree of sleep apnea symptoms.
The team found that approximately 82.7 percent of patients had an apnea-hypopnea index (AHI) ≥ 5, with 42.1 percent of those studied having an AHI ≥ 15. The researchers also determined that the predominant type of sleep apnea affecting these patients was obstructive and that AHI increased with:
- Age
- BMI
- Waist and neck circumference
- Body and visceral fat
Importantly, the researchers also found no association between ESS and AHI and stated in their conclusions that “The high prevalence of SA detected in this study may indicate that SA is under-recognized in patients with AF.”
They also reported that none of the screening questionnaires predicted SA reliably.
The prevalence of undiagnosed sleep apnea in patients with symptomatic atrial fibrillation
The second study we will discuss, briefly titled, “Prevalence of OSA in patients with AF”, set out to examine the prevalence of sleep apnea in atrial fibrillation patients referred for ablation.
This stated goal is due to the fact that while sleep apnea is known to be common if atrial fibrillation patients and is also associated with atrial remodeling as well as a high recurrence post-ablation, the prevalence of atrial fibrillation patients with undiagnosed sleep apnea had not been well established.
The research team recruited 188 patients scheduled to undergo ablation and who had no prior diagnosis of sleep apnea. All participants were required to complete the STOP-Bang sleep apnea screening questionnaire and undergo home sleep apnea testing.
The results of the home sleep apnea testing were positive in 82.4 percent of participants without a prior diagnosis of sleep apnea as follows:
- Mild- 43.8 percent
- Moderate- 32.9 percent
- Severe- 23.2 percent
For all positive participants a predominantly obstructive component was observed.
The researchers also found that a positive STOP-Bang questionnaire was not predictive for sleep apnea and that symptoms of the condition, including snoring, daytime sleepiness, and observed apneic episode were reported at a similar frequency in patients positive and negative for sleep apnea.
The conclusion of the study was that while undiagnosed sleep apnea is exceedingly prevalent in patients with atrial fibrillation who are referred for ablation, the use of screening questionnaires or symptom evaluation for diagnosis has limited predictive value.
The authors also stated that, “A universal SA screening strategy may be considered in all patients with symptomatic AF.”
Home sleep apnea testing enhances diagnosis and care
The results of these studies mean that physicians treating atrial fibrillation patients can no longer afford to rely upon screening questionnaires for sleep apnea diagnosis, since these tools are failing to pinpoint the condition accurately, which ultimately translates to a failure to provide appropriate care.
Instead, home sleep apnea testing is necessary on a broad scale for patients with atrial fibrillation so that they can receive the necessary treatment with continuous positive airway pressure ventilators to improve atrial fibrillation control.