Obstructive sleep apnea and the day-night pattern of paroxysmal atrial fibrillation burden

Obstructive sleep apnea (OSA) is a common condition that contributes to atrial fibrillation occurrence, but the evidence on day-night pattern of paroxysmal atrial fibrillation (PAF) is still scanty. The aim of this study was to evaluate whether OSA is associated with a higher occurrence of PAF and especially PAF events during the nighttime and determine the frequency and potential underdiagnoses of OSA in patients with PAF. We recruited consecutive patients who had undergone a recent 24-hour Holter monitoring and showed at least one episode of PAF. All patients were invited to perform a clinical evaluation. To assess OSA status, we conducted validated portable sleep monitoring. OSA was defined by an apnea-hypopnea index ≥15 events per hour. We studied 102 patients (mean age: 64±9 years, 56% male). Sixty patients (57%) had OSA (none with a previous diagnosis). A total of 339 episodes of PAF (a third of them occurring at night) were available for analysis. We observed a significant association between OSA and nighttime PAF episodes: patients with OSA had a higher chance of nighttime episodes than those without OSA (OR: 1.78, 95% CI: 1.12-2.83; p=0.014). Interestingly, the distribution of PAF episodes over 24 hours showed that patients with OSA had more AF episodes between 10PM and 4AM than patients without OSA (OSA: 10 [7.5-11] vs. No OSA: 2 [3-5.5]; p=0.037), suggesting an abnormal day-night pattern of the PAF occurrence. OSA is common, underdiagnosed, and associated with a higher nighttime occurrence of PAF episodes than patients without OSA.