Cardiac remodeling, autonomic parameters, and clinical factors associated with obstructive sleep apnea: a case-control study

Abstract

Background: Obstructive sleep apnea (OSA) is associated with substantial cardiovascular morbidity through mechanisms involving intermittent hypoxia, sympathetic activation, oxidative stress, and progressive cardiac remodeling. The present study aimed to comprehensively evaluate clinical characteristics, echocardiographic abnormalities, autonomic function, and independent factors associated with OSA in a case-control population.

Methods: This observational, case-control study included 108 adults recruited from a tertiary sleep laboratory, 54 patients with OSA and 54 controls selected using frequency matching for age and sex and considered at low risk for OSA based on STOP-Bang screening. Clinical characteristics, cardiovascular risk factors, transthoracic echocardiographic parameters, structural cardiac abnormalities, and 24-hour Holter-derived autonomic indices were compared between groups. Continuous variables were analyzed using the Mann-Whitney U test, categorical variables using Pearson's chi-square or Fisher's exact test, and univariable and multivariable binary logistic regression analyses were performed to identify variables independently associated with OSA.

Results: Compared with controls, patients with OSA had significantly higher prevalences of obesity, smoking, hypertension, diabetes mellitus, and ischemic heart disease (IHD). Echocardiography demonstrated larger left atrial and right ventricular diameters, higher pulmonary artery systolic pressure (PASP), and increased frequencies of left ventricular hypertrophy (LVH), diastolic dysfunction, and moderate tricuspid regurgitation (TR). Among the Holter-derived autonomic parameters, the root mean square of successive differences between adjacent normal-to-normal intervals (RMSSD) was significantly lower in patients with OSA in the unadjusted comparison. In multivariable linear regression analyses, the association between OSA and RMSSD was attenuated and did not reach statistical significance, while OSA was not independently associated with the standard deviation of normal-to-normal intervals (SDNN). In univariable logistic regression analyses, obesity, smoking, hypertension, diabetes mellitus, ischemic heart disease, left ventricular hypertrophy, and diastolic dysfunction were significantly associated with OSA. After multivariable adjustment, obesity [adjusted odds ratio (OR) 10.86, 95% confidence intervals (CI) 2.99–39.47], smoking (adjusted OR 4.88, 95% CI 1.32–18.14), ischemic heart disease (adjusted OR 19.17, 95% CI 1.65–222.41), and left ventricular hypertrophy (adjusted OR 3.54, 95% CI 1.01–12.40) remained independently associated with OSA.

Conclusions: OSA was associated with structural cardiovascular abnormalities and an unadjusted difference in the Holter-derived autonomic parameter RMSSD, whereas neither RMSSD nor SDNN showed a statistically significant independent association with OSA after multivariable adjustment. Obesity, smoking, ischemic heart disease, and left ventricular hypertrophy were independently associated with the presence of OSA, underscoring the close relationship between sleep-disordered breathing and cardiovascular disease. Comprehensive cardiovascular evaluation may improve risk stratification and support earlier identification of patients at increased cardiovascular risk.