Central sleep apnea (CSA) occurs in up to 40% of HF patients (pts.) and portends poor prognosis. Phrenic nerve stimulation (PNS) by implantable remedē System (Respicardia, Inc, Minnetonka, MN, USA) causes diaphragmatic contraction like normal breathing and produces improvement in sleep and quality of life in pts. with CSA of different etiologies (Pivotal Trial). Methods: Exploratory analyses were done in 80 Pivotal Trial pts. (61%) identified as having HF. Polysomnograms (PSG) (interpreted by

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... inded laboratory) had to show predominant CSA ≥ moderate. Randomization was 1:1 to therapy initiated at 1 month [treatment (T)] or delayed 7 months [control (C)]. CSA HF pts. had ML-WHF scored at 1 year. Echocardiograms were evaluated by a blinded laboratory. Freedom from related SAEs, time to first HF hospitalization, and death through 12 months were assessed. Results: 35 T and 45 C HF pts. were similar at baseline. LVEF (35±2%) was ≤45% in 60 pts.(79%). Apnea-hypopnea index (AHI) (events/h) was 50±19 in the T group and 44±17 in HF C. At 6 months, compared to HF C, the HF T group had a greater % of subjects with ≥50% AHI reduction [63% vs. 4%; p<0.0001; between groups difference=58% (p<0·0001)] and significant improvements in sleep and patient-reported outcomes. 5% of the HF T group and 17% of C had a HF hospitalization in 6 months (Kaplan-Meier). There was no mortality difference between groups through 6 months. Improvements in sleep and patient-reported outcomes persisted in the HF T pts. after 1 year of therapy. At 12 months, the MLWHF scores improved in the HF T group (-6.3±17.0; p=0.044) and, in pts. with LVEF ≤45%, LVEF (5.0±7.0; p=0.002) and LVESV (-10.8±27.0; p=0.053) also improved. 12month freedom from related SAEs was 92%. Conclusions: In HF pts., CSA treatment with PNS produces sustained clinical improvements that are associated with evidence of reverse remodeling in pts. with reduced LVEF. The trend toward fewer HF hospitalizations when CSA is treated by PNS should be confirmed in future studies. Acknowledgement/Funding: Respicardia, Inc, Minnetonka, MN, USA