Author + information
- Christoph Scharf, MD* (, )
- Alexander Turk, MD,
- Thomas Brack, MD and
- Konrad Bloch, MD
- ↵*Department of Internal Medicine, Division of Cardiology, University Hospital Zürich, Rämistrasse 100, 8091 Zürich, Switzerland
We congratulate Sinha et al. (1) for their interesting and innovative report in JACCon the therapeutic effect of biventricular pacing on central sleep apnea (CSA). A few questions remain: the title suggests some information about Cheyne-Stokes respiration (CSR), which is not equivalent to CSA; however, results are lacking. Were all apnea/hypopnea events central in nature or did some also have obstructive or mixed events? Completely blinded serial scoring is difficult in patients undergoing an intervention such as an implantation device, and therefore a bias in visual scoring might be possible. We would be interested in learning some additional objective values such as desaturation index or time in apnea. This would be of greater value than minimum SaO2in their Table 3.
In their discussion, the investigators state that CSA is related to heart failure, a statement that contrasts to similar findings on exercise and echocardiography in both groups. In view of this, how do the researchers explain the dramatic effects of cardiac resynchronization therapy (CRT) on CSA when the benefit of CRT (on echocardiography and exercise) is equal in patients with and without CSA? Moreover, the effect of CRT on sleep apnea, as described by Sinha et al. (1), is huge and much higher than in our experience and even higher than after cardiac transplantation (2,3). In these reports, cyclic respiration/CSR was abolished, but sleep apnea persisted or got worse in a considerable number of patients.
- American College of Cardiology Foundation