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BACKGROUND Obstructive sleep apnea (OSA) is associated with several cardiovascular conditions. Some pacemakers feature specific algorithms detecting respiratory cycles and deriving indices well correlated with the identification of polysomnography-confirmed severe OSA. OBJECTIVES The purposes of this study were to analyze respiratory disturbances measured by a validated algorithm in clinical practice and to describe their variability over time and their association with atrial fibrillation. METHODS Fifty-eight patients implanted with dual-chamber LivaNova REPLY 200 DR or KORA 100 DR pacemakers measuring a respiratory disturbance index (RDI) were included. An RDI >20 events per hour of sleep is well correlated with severe OSA as determined by polysomnography. Patients with >10% nights with invalid RDI measurements were excluded. RESULTS The RDI could be measured during 98% of nights. During a mean follow-up of 187 ± 123 days, the individual mean RDI was 19.9 ± 12.7 and was superior to 20 in 24 patients (41%). An RDI >20 events/h in at least 1 night was observed in 52 patients (90%). The mean day-to-day RDI variability in individual patients was 19% ± 21%. Patients with the highest burden of severe OSA (as defined by ≥75% of nights with RDI >20 events/h) were older, had a higher prevalence of hypertension, and were more often implanted for atrioventricular block than patients with lower burden of severe OSA. No RDI burden or cutoff was a predictor of atrial fibrillation occurrence. CONCLUSION OSA is frequent in patients with a pacemaker and is reliably detected by pacemakers. OSA is highly variable and could probably be best analyzed in terms of burden.