Background: Obstructive sleep apnoea (OSA) and atrial fibrillation (AF) are two conditions highly prevalent in the general population. OSA is known to cause haemodynamic changes, oxidative stress, and endothelial damage, and therefore promote vascular and heart remodelling which results in AF triggering and exacerbation. Coexistence of OSA and AF influences the course of both diseases, and therefore should be taken into consideration in patient management strategy planning.

Aim: To assess the prevalence of OSA in Polish AF patients, and to describe the clinical characteristics of patients with concomitant OSA and AF.

Methods: We enrolled into the study 289 consecutive patients hospitalised in a tertiary, high-volume Cardiology Department with a primary diagnosis of AF. In addition to standard examination, all patients underwent an overnight sleep study to diagnose OSA, which was defined as apnoea–hypopnoea index (AHI) ≥ 5 per hour.

Results: After applying exclusion criteria, the final analysis covered 266 patients (65.0% male, mean age 57.6 ± 10.1 years). OSA was present in 121 (45.49%) patients. Patients with OSA were older (59.6 ± 8.0 vs. 56.0 ± 11.4 years; p = 0.02), had higher body mass index (BMI; 30.9 ± 5.4 vs. 28.7 ± 4.4 kg/m²; p < 0.01) larger neck size (41.2 ± 3.8 vs. 39.3 ± 3.3 cm; p = 0.0001) and waist circumference (108.5 ± 13.1 vs. 107.7 ± 85.4 cm; p < 0.0001) than patients without OSA. There were no significant differences between the groups in terms of systolic and diastolic blood pressure or history of comorbidities (p > 0.05). OSA patients were less likely than non-OSA patients to have paroxysmal AF (62.0% vs. 75.9%; p = 0.02). Dividing newly diagnosed OSA patients according to the disease severity showed that mild OSA (AHI ≥ 5/h and < 15/h) was present in 27.82% of the study population, moderate OSA (AHI ≤ 15/h and ≥ 30/h) in 13.16% of patients, and severe OSA (> 30/h) in 4.51% of patients. No significant differences in terms of comorbidities and anthropometric features were seen between mild and moderate, between moderate and severe, and between mild and severe OSA.

Conclusions: OSA is highly prevalent in patients with AF in the Polish population, and affects approximately half of the patients. OSA patients are more likely to be older, have higher BMI, and greater waist and neck circumference. Persistent AF is the most common form of the arrhythmia in patients with OSA, while patients without OSA are more likely to have paroxysmal AF.