Association of Central Sleep Apnea with Impaired Heart Structure and Cardiovascular Hemodynamics in Patients with Chronic Heart Failure

Background: Advanced heart failure (HF) is commonly accompanied by central sleep apnea (CSA) with Cheyne- Stokes respiration (CSR). The aim of this study was to evaluate the relationship between CSA/CSR and other clinical features of HF, with particular emphasis on cardiovascular hemodynamics. Material/Methods: In 161 stable HF patients with left ventricular ejection fraction (LVEF) <= 45% (NYHA class I-III; mean LVEF 32.8%) the clinical evaluation included: LVEF; left and right ventricular end-diastolic diameter (LVDd, RVDd); ratio of early transmitral flow velocity to early diastolic septal mitral annulus velocity (E/e') assessed by echocardiography; stroke index (SI); heart rate (HR); cardiac index (CI); and systemic vascular resistance index (SVRI) assessed by impedance cardiography (ICG). The comparison was performed between 2 subgroups: one with moderate/severe CSA/CSR - CSR_ [+] (n= 51), and one with mild or no CSA/CSR - CSR_ [-] (n= 110). Results: CSR_ [+] patients presented more advanced NYHA class (p<0.001) and more frequently had permanent atrial fibrillation (p=0.018). Moreover, they had: lower LVEF (p<0.0001); higher LVDd (p<0.0001), RVDd (p<0.001), and E/e' (p<0.001); lower SI (p<0.001) and CI (p=0.009); and higher HR (p=0.044) and SVRI (p=0.016). The following predictors of CSR_ [+] were identified: NYHA class (OR=3.34 per class, p<0.001, which was the only independent predictor); atrial fibrillation (OR=2.29, p=0.019); RV enlargement (OR=2.75, p=0.005); LVEF<35% (OR=3.38, p=0.001); E/e' (OR=3.15; p=0.003); and SI<35 ml/m(2) (OR=2.96, p=0.003). Conclusions: Presence of CSA/CSR in HF is associated with NYHA class, atrial fibrillation and more advanced impairment of cardiovascular structure and hemodynamics. Patient functional state remains the main determinant of CSR.