0041 : Sleep disordered breathing in heart failure: nocturnal desaturation as a novel prognostic marker. A prospective cohort study on 376 patients

Abstract

Sleep disordered breathing (SDB) is common in patients with heart failure with reduced ejection fraction (HFrEF). Increased apnoeahypopnoea index (AHI) is predictive of poor outcome. Nocturnal desaturation (ND) is associated with increase in NT-proBNP in HFrEF. The prognostic value of ND as compared to AHI is still unknown. Three-hundred seventy six consecutive patients with stable chronic HFrEF and left ventricular ejection fraction (LVEF) ≤45% were prospectively screened for SDB between 2005 and 2010 by polygraphy. SDB was defined by an AHI≥5 and sleep apnea (SA) by an AHI≥15. Mean age was 59±13 years, mean LVEF 30%±6%, and mean AHI 18±10; 310 patients (82%) had SDB. The predefined composite primary end-point (death, heart transplantation or left ventricular assistance) occurred in 98 patients (26%) within 3 years. Minimal oxygen saturation (MOS) during sleep, number of desaturations <90%/hour and time spent with oxygen saturation <90% were significantly associated with adverse events (HR 1.25, 1.25, and 1.28 respectively) after adjustment for confounders, whereas AHI was not. Best MOS cut-off value for poor outcome was ≤88%. Patients with MOS ≤88% without SA had similar event rates than those with MOS ≤88% with SA. Patients with MOS ≤88% had a significantly higher event rate than those with MOS >88% (p<0.01). Risk assessment using MOS of ≤88% in addition to established prognostic markers of HFrEF yielded a net reclassification index (NRI) of nearby 6%, and was particularly useful in the subgroup of patients with events (NRI 8,4%). In HFrEF, nocturnal desaturation ≤88% is a stronger predictor of adverse events than AHI, independently of the presence of SA. This suggests that risk assessment in HFrEF should include MOS, and that SDB treatment may also focus on patients without SA presenting nocturnal desaturation.