Obstructive sleep apnea phenotypes associated with atrial fibrillation

Necessity of treating obstructive sleep apnea (OSA) to treat atrial fibrillation (AF) remains unclear. Observational studies demonstrated less AF recurrence when patients were treated with continuous positive airway pressure, however randomized trials demonstrated no effect. These studies included based on the apnea-hypopnea index (AHI). Certain OSA-phenotypes however carry a higher cardiovascular risk; comorbid insomnia and sleep apnea (COMISA) is associated with increased incidence of myocardial infarction and heart failure compared to minimally symptomatic subtypes. Data on phenotypes with higher susceptibility for AF is lacking.

We hypothesize there are OSA-phenotypes that better reflect the susceptibility to AF, compared to AHI. The aim of this study is to identify these OSA-phenotypes to direct future studies on whether AF treatment is improved when the patients with arrhythmic OSA-phenotypes are treated.

We included patients with paroxysmal or persistent AF and a high risk of OSA. Patients were referred for sleep-related medical history taking and polysomnography (PSG). Patients with OSA (AHI>5) were matched for age, sex and body mass index (BMI) in a 1:2 distribution with OSA-patients who had their PSG in the same sleep centre. Continuous variables were expressed as median (interquartile range). Continuous data was compared using the Mann–Whitney-U test. Categorical data with the Chi2-test.

128 of 155 patients with AF and OSA (AF+ group, 27% female, median age 62, median BMI 29.1) were matched with 204 patients with OSA (AF- group, 28% female, median age 61, median BMI 28.3).

AHI did not differ significantly between the AF+ and AF- group. Compared to the AF- group, the AF+ group spend more time in lateral position (77.5% vs 55%, p<.001) and less in supine (20.2% vs 30.3%, p0.005). The AF+ group had more awakenings and arousals during PSG (p0.02 and 0.03 respectively), though they scored lower on an insomnia symptom questionnaire (p<.001) compared to the AF- group. Heart rate variability analysis demonstrated higher root mean square of successive differences (RMSSD) in the AF+ group, across all sleep stages, compared to the AF- group. Hypoxic burden did not differ significantly, nor did the incidence of comorbidities (COMISA, periodic limb movement disorder, positional OSA).

In this study, more time spent in the lateral body position and a high vagal tone were markers for an proarrhythmogenic OSA-phenotype. The proarrhythmogenicity of both the lateral body position and a high vagal tone, especially in nocturnal AF, have been described. Poor sleep quality and insomnia are associated with AF. In this study, the AF+ group experienced more awakenings and arousals during PSG, but their lower Insomnia Severity Index indicated less insomnia symptoms, hampering a clear conclusion. .

Future studies on OSA and AF should endeavour to seek if the selection and treatment of patients with an arrhythmogenic OSA-phenotype improves the treatment of AF.

Sleep characteristics