Apnea–hypopnea and Desaturations in Heart Failure with Reduced Ejection Fraction: Are We Aiming at the Right Target?

Background Sleep disordered breathing (SDB) is common in patients with heart failure with reduced ejection fraction (HFrEF). An increased apnea–hypopnea index (AHI) is associated with poor outcomes. We examined whether an analysis of nocturnal desaturations (NDs) can improve the risk stratification. Methods Three-hundred seventy-six consecutive patients with stable chronic HFrEF and LVEF ≤45% were prospectively screened using polygraphy. Sleep apnea (SA) was defined as an AHI ≥15. The mean age was 59±13years, the mean LVEF was 30±6%, and the median AHI was 18 [IQR: 9.33). The composite end-point of death, heart transplantation or LV assistance occurred in 98 patients (26%) within 3years. Minimal oxygen saturation (MOS) during sleep, the number of desaturations <90%/h and the time spent with oxygen saturation <90% were significantly associated with adverse events (adjusted HR 1.25 [1.03–1.52], 1.25 [1.03–1.53], and 1.28 [1.04–1.59]), whereas the AHI was not (1.10 [0.86–1.39]). The best MOS cut-off value for poor outcomes was ≤88%. The patients with an MOS ≤88% had a significantly higher event rate (31.9%) than those with an MOS >88% (15.6%; p<0.01). The risk assessment using an MOS of ≤88% in addition to established prognostic markers yielded a net reclassification index (NRI) of nearly 6% and was particularly useful in the subgroup of patients with events (NRI: 8.4%). Conclusions In HFrEF patients, ND ≤88% appears to be predictive of adverse events, independent of the presence of SA. This suggests that the risk assessment in HFrEF should also include ND in top of AHI.