Influence of Obstructive Sleep Apnea on Right Heart Structure and Function

Introduction: Obstructive sleep apnea syndrome (OSAS) is a highly prevalent sleep disorder associated with increased cardiovascular morbidity and mortality. This study aimed to investigate heart structure and function and their correlation with the degree of OSAS and sleep indexes in patients diagnosed with OSAS. Materials and methods: A cohort of 77patients (48 males, aged 58.1 ± 11.0 years, body mass index [BMI] = 32.4 ± 6.2) admitted to the hospital due to suspected OSAS was examined using echocardiography and polysomnography. Results: Patients with moderate-to-severe OSAS compared to patients without diagnosed OSAS or with mild OSAS had greater right ventricular outflow tract (RVOT) dimensions (32.6 ± 3.6 vs. 30.9 ± 2.4 mm; p < 0.05), larger right atrial area (RAA; 21.1 ± 4.8 vs. 17.2 ± 3.2 mm; p = 0.002), greater right ventricular mid-cavity diameter (RVD; 35.5 ± 7.0 vs. 32.2 ± 4.7 mm; p = 0.02), and diminished tricuspid annular plane systolic excursion (TAPSE, 21.9 ± 4.5 vs. 25.8 ± 4.4 mm; p = 0.04), while there were no significant differences in tissue doppler imaging (TDI) parameters (S’ and E’) and in valvular regurgitation gradient for both groups. Moreover, significantly greater RVOT dimensions (31.6 ± 2.6 vs. 30.9 ± 3.0 mm, p = 0.04), RVD (39.3 ± 7.0 vs. 32.7 ± 5.2 mm, p = 0.003), and RAA (21.4 ± 4.4 vs. 18.1 ± 4.2 mm, p = 0.02) as well as reduction in TAPSE (20.9 ± 5.3 vs. 25.0 ± 4.3 mm, p = 0.01) were observed in patients having ≥ 10 episodes of obstructive apnea (OA) per hour. Conclusions: In moderate-to-severe OSAS patients, right ventricular (RV) enlargement was observed together with RV dysfunction as measured by TAPSE. Examination using TDI is not superior to standard echocardiography for the detection of heart pathology in OSAS patients. Right heart pathology is present predominantly in patients with obstructive apnea.