Unilateral phrenic nerve stimulation in the therapeutical algorithm of central sleep apnoea in heart failure Purpose of review Central sleep apnoea (CSA) is highly prevalent in patients with heart failure and substantially impairs survival. If optimal cardiac treatment fails, alternative therapeutical options, including positive airway pressure (PAP) therapies, drugs or application of oxygen and carbon dioxide are considered to suppress CSA which interfere with the complex underlying pathophysiology. Most recently, unilateral phrenic nerve stimulation (PNS) has been studied in these patients. Therefore, there is an urgent need to critically evaluate efficacy, potential harm and positioning of PNS in current treatment algorithms. Recent findings Data from case series and limited randomized controlled trials demonstrate the feasibility of the invasive approach and acceptable peri-interventional adverse events. PNS reduces CSA by 50%, a figure comparable with continuous PAP or oxygen. However, PNS cannot improve any comorbid upper airways obstruction. A number of fatalities due to malignant cardiac arrhythmias or other cardiac events have been reported, although the association with the therapy is unclear. Summary PNS offers an additional option to the therapeutical portfolio. Intervention-related adverse events and noninvasive alternatives need clear discussion with the patient. The excess mortality in the SERVE-HF study has mainly been attributed to sudden cardiac death. Therefore, previous cardiac fatalities under PNS urge close observation in future studies as long-term data are missing. Correspondence to Winfried Randerath, MD, Professor of Medicine, Clinic for Pneumology and Allergology, Centre of Sleep Medicine and Respiratory Care, Institute of Pneumology at the University of Cologne, Bethanien Hospital, Aufderhöher Str. 169, 42699 Solingen, Germany. E-mail: randerath@klinik-bethanien.de Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.