Sleep apnea in heart failure: in search of a better prognosis predictor

Abstract

Abstract Background Sleep apnea (SA) is a burdensome and often underdiagnosed condition in heart failure (HF). Portable devices, such as ApneaLinkTM, are currently validated as a screening tool for SA. The apnea-hypopnea index (AHI) as been long considered the gold-standard measurement for the diagnosis of SA, also having a prognosis impact. Recently, however, other respiratory variables have been proposed as better prognosis predictors in patients with HF. The main goal of this study was to assess the prognostic value of other respiratory measurements evaluated by ApneaLinkTM at discharge in a population admitted for HF. Methods This was a single-center retrospective study enrolling consecutive patients admitted in a HF Clinic for acute HF from 2013 and 2018. All stable patients without previously known sleep-disordered breathing underwent ApneaLinkTM screening the night before discharge in the euvolemic state. Those with a total respiratory evaluation time <180 minutes or in need of supplemental oxygen were excluded. A primary endpoint of long-term HF hospitalizations was evaluated. Results Overall, 231 patients (mean age 74.5±10.6 years; 47% male; 83% hypertension; 41% chronic kidney disease; 44% anemia; 18% with a NYHA>2 at discharge; 43% ischaemic HF; 41% with a left ventricle ejection fraction lower than 50%) were assessed. One-hundred and sixty-nine patients (59.1%) had an AIH >15, with a median of 19 (IQR 7–42); the median number of obstructive apneas and central apneas was 13 (IQR 2–68), and 2 (IQR 0–10), respectively. Two-hundred patients (69.9%) had nocturnal periods of an oxygen saturation below 85% (T85), with a median time under that value of 8 (IQR 0–47) minutes. Over a median follow-up of 34.1 (IQR 18.40–54.37) months, 105 (45.7%) patients died and 128 (55.7%) were readmitted for AHF. After adjustment for cofounders (namely, the presence of anemia) a T85 above the 75th percentile was significantly correlated with a higher risk of HF readmission in a multivariate analysis (adjusted HR: 1.58, 95% CI: 1.08–2.30, p=0.017) (figure 1). These results were independent of the apnea-hypopnea index. Conclusion Nocturnal hypoxemia (T85) was an independent predictor of rehospitalization in patients with HF. These results further validate the utility and prognosis impact of other respiratory measurements (other than AHI) evaluated by ApneaLinkTM screening at discharge in a population of patients admitted for HF. Figure 1 Funding Acknowledgement Type of funding source: None