Introduction: Obstructive sleep apnea (OSA) induces repetitive collapse of the upper respiratory airways, despite a normal activation of the respiratory muscle groups. Repetitive nocturnal hypoxia is responsible for the overactivation of the sympathetic nervous system and increases the risk of developing arrhythmias. The role of CPAP therapy (Continuous Positive Airway Pressure) in the management of OSA-related arrhyth-mias is debatable.

Objective: To illustrate rhythm disturbances among patients with moderate-severe OSA.

Methods: We conducted a transverse study that in-cluded 71 patients aged 36-79 years old, with moderate-severe OSA (average apnea-hypopnea index (AHI) 40.46 ± 19.88 events/h), that were admitted in the Car-diovascular Rehabilitation Clinic between september 2017 – december 2018. All patients signed an informed consent and underwent clinical examination and 24-hour Holter ECG recording. Statistical analysis was performed using SPSS v. 20.0. A p value <0.05 was con-sidered statistically significant.

Results: A high percentage of patients (86.76%) pre-sented supraventricular extrasystoles (mostly couplets – 43.47%) and ventricular ectopic beats (71.42%). The prevalence of atrial fibrillation and flutter was 7.14% and 2.85%. 64.44% of patients were under beta-blocker treatment (nebivolol, bisoprolol, metoprolol and car-vedilol – 25.86%, 22.41%, 10.34% and 5.17%, respecti-vely). We found a significant correlation between AHI, minimal nocturnal saturation and average 24 h heart rate (HR) (r=0.29, p=0.01 and r=-0.25, p=0.03, respec-tively). The maximum R-R pause is correlated with the desaturation index (r=0.23, p=0.04) and with minimal nocturnal saturation (r=-0.371, p=0.001). Patient age influences both average HR (r=-0.26, p=0.02) and ma-ximum 24 h HR (r=-0.32, p=0.005).

Conclusions: T he most frequent arrhythmias among patients with moderate-severe OSA are ventricular and supraventricular ectopic beats. Nebivolol was the most frequently prescribed beta-blocker in our study group, probably because of the high percentage of diabetics among our OSA patients. The prevalence of atrial fi-brillation is higher in OSA subjects than in the general population. 24 h average HR was correlated with OSA severity, minimum nocturnal saturation and patient’s age.