Cardiac Arrhythmias and Heart Rate Variability in High Cardiovascular Risk Patients With Obstructive Sleep Apnea: A Prospective Observational Study

Background and Objective To describe the prevalence of cardiac arrhythmias and evaluate associations between heart rate variability (HRV) parameters and clinical characteristics in high cardiovascular risk patients with obstructive sleep apnea (OSA).Methods This prospective observational study included 50 adults diagnosed with OSA by respiratory or sleep polygraphy at the Respiratory Center and the Vietnam National Heart Institute, Bach Mai Hospital, between August 2024 and June 2025. All participants underwent 24-hour Holter electrocardiography to detect arrhythmias and assess HRV using time-domain indices: standard deviation of normal-to-normal intervals (SDNN), standard deviation of the average normal-to-normal intervals (SDANN), and root mean square of successive differences (rMSSD). Additional subgroup analyses were performed after excluding patients with atrial fibrillation (AF) because AF may influence HRV measurements.Results Among the participants, 68% were male; 13 had mild OSA, 18 moderate OSA, and 19 severe OSA. The most common arrhythmias were AF (52%), premature atrial contractions (30%), and premature ventricular contractions (28%). HRV indices did not differ significantly across OSA severity groups. In the overall cohort, SDANN showed significant inverse correlations with neck circumference (r=-0.555, p=0.032), body mass index (r=-0.533, p=0.041), and apnea–hypopnea index (r=-0.536, p=0.040). These associations remained significant in the non-AF subgroup. No significant correlations were observed for rMSSD.Conclusions Cardiac arrhythmias were common in this high cardiovascular risk OSA cohort. Lower SDANN values were associated with anthropometric parameters and OSA severity. Larger studies are needed to confirm these findings.