Clinical and prognostic role of sleep-related breathing disorders in patients with heart failure depending on body mass index

Abstract

Aim. To determine the clinical features of sleep-related breathing disorders (SRBDs) and their prognostic role in patients with heart failure with reduced ejection fraction (HFrEF) depending on the body mass index (BMI).Material and methods. This prospective cohort study included 111 patients with HFrEF who were hospitalized with symptoms of decompensated heart failure. All patients underwent a standard examination and polysomnography after HF compensation. Patients with HF were divided into 3 groups depending on the body mass index: group 1 — BMI of 18,5-25 kg/m2, group 2 — BMI 25-30 kg/m2, group 3 — BMI ≥30 kg/m2. Primary endpoint was all-cause mortality. The median follow-up was 918 (163; 2495) days. Information was collected twice a year through telephone contacts.Results. In the 1st group, SRBDs occurred in 74% of cases, while in overweight and obese patients — in 84% and 86% of patients, respectively. In multiple comparisons of the three groups, the hypopnea index and apnea/hypopnea index (AHI) in the REM sleep were significantly different (p<0,05), when pairwise comparison revealed significant differences only between groups 1 and 3. Hypoxemia, estimated by average saturation ((95 (94,1-95,75), 96 (95,5-96,3), and 92,05 (91,6-92,5), p=0,0001) and average desaturation (5,9 (5,2-7,25), 4,1 (3,8-8,8), and 10 (8,6-11,4), p=0,002), was more pronounced in groups with obesity. In groups 1 and 2, negative correlations were observed between average oxygen saturation and BMI (r=-0,398, p=0,012 and r=-0,635, p=0,0001), which was not observed in patients with obesity. Survival analysis showed a worse prognosis in patients with normal BMI with and without moderate sleep apnea, while obese patients without moderate sleep apnea had a better prognosis than overweight patients (log-rank=5,989, p=0,05).Conclusion. In patients with HFrEF, obesity is associated with a higher incidence of severe apnea, more severe hypoxemia, which does not correlate with BMI. The worst prognosis was observed in patients with normal BMI, while the most favorable prognosis — in obese patients without moderate sleep apnea.