Sleep disordered breathing and post-discharge mortality in patients with acute heart failure

Background: Hospitalizations for heart failure are associated with a high post-discharge risk for mortality. Identification of modifiable predictors of post-discharge mortality during hospitalization may improve outcome. Sleep disordered breathing (SDB) is the most common co-morbidity in heart failure patients.

Design, setting, and participants: Prospective cohort study of patients hospitalized with acute heart failure (AHF) in a single academic heart hospital. Between January 2007 and December 2010, all patients hospitalized with AHF who have left ventricular ejection fraction (LVEF) ≤ 45% and were not already diagnosed with SDB were the target population.

Main outcomes and measures: Patients underwent in-hospital attended polygraphy testing for SDB and were followed for a median of 3 years post-discharge. Mortality was recorded using national and state vital statistics databases.

Results: During the study period, 1117 hospitalized AHF patients underwent successful sleep testing. Three hundred and forty-four patients (31%) had central sleep apnoea (CSA), 525(47%) patients had obstructive sleep apnoea (OSA), and 248 had no or minimal SDB (nmSDB). Of those, 1096 patients survived to discharge and were included in the mortality analysis. Central sleep apnoea was independently associated with mortality. The multivariable hazard ratio (HR) for time to death for CSA vs. nmSDB was 1.61 (95% CI: 1.1, 2.4, P = 0.02). Obstructive sleep apnoea was also independently associated with mortality with a multivariable HR vs. nmSDB of 1.53 (CI: 1.1, 2.2, P = 0.02). The Cox proportional hazards model adjusted for the following covariates: LVEF, age, BMI, sex, race, creatinine, diabetes, type of cardiomyopathy, coronary artery disease, chronic kidney disease, discharge systolic blood pressure <110, hypertension, discharge medications, initial length of stay, admission sodium, haemoglobin, and BUN.

Conclusions: This is the largest study to date to evaluate the effect of SDB on post-discharge mortality in patients with AHF. Newly diagnosed CSA and OSA during AHF hospitalization are independently associated with post-discharge mortality.