I agree with Dr MT Naughton's interesting opinion expressed in ‘Cheyne-Stokes respiration: friend or foe?’ in his recent opinion in Thorax. 1 Central sleep apnoea with Cheyne-Stokes respiration (CSA-CSR) indeed has multiple features more likely to be compensatory than injurious in heart failure (HF). His view, however, seems to lack insight into the heart–lung interaction in CSA-CSR, and reminds me of the fundamental question of ‘why does the heartbeat synchronise with respiratory rhythm?’.2

In polygraphic recording in a HF patient with CSA-CSR (figure 1A), heartbeats are clustered during the hyperventilation period and scattered during the apnoeic period of CSR-CSA with cycle-length of approximately 90 s. This phenomenon is known as …