Reader response to "A Case of Sleep Disordered Breathing After Coronary Artery Bypass Graft Surgery"
Thank you for the excellent case of the patient with CSR after a recent MI/CABG. I definitely learned some new things, so many thanks for your time and effort on this.
I did have one question/concern regarding the last item in the case, regarding what therapies one might consider if CSA persisted in follow-up. My concern about the "correct" CPAP answer lies in the interpretation of the CANPAP results. While it is true that CPAP did not improve transplant-free survival, I think we should be very concerned about the fact that the study's DSMB stopped the trial early due in part to the early divergence of the survival curves, favoring control (i.e. randomization to CPAP = higher early mortality/transplantation). Yes, there was a post-hoc analysis that showed that if CPAP got rid of CSR, these patients did better than control, but this was a post-hoc analysis with incomplete follow-up data.
I guess my main concern is that readers might interpret the case discussion and conclude that using CPAP is fine for heart failure with central apnea. I agree with the statements that CPAP improved LVEF, norepi levels, and 6-min walk distance, but what about the early death/transplant events?
Kind regards,
Ken
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Ken M. Kunisaki, M.D.
Assistant Professor
University of Minnesota
Minneapolis VA Medical Center
Pulmonary, Critical Care, Sleep Medicine (111N)
One Veterans Drive, Minneapolis, MN, 55417
Dear Dr. Kunisaki,
I would like to thank you for your comment regarding our clinical case. There is indeed no current consensus on which treatment modality has to be instituted in a patient with chronic heart failure (CHF) with a central sleep apnea syndrome (CSA). We share your concern for the possibility of deleterious effects of positive airway pressure (PAP) therapy in some patients with CHF resulting from incomplete resolution of the CSA. However, we have to acknowledge that the few currently available data suggest that from a practical point, in a CHF patient with CSA, it should be requested a complete resolution of the central sleep apnea events with PAP therapy (CPAP or adaptive servo ventilation), in order to avoid potential deleterious outcomes. The recent Canadian Thoracic Society guidelines state, that if CSA syndrome persists after optimal medical HF treatment has been established, CHF patients should be considered for a three-month trial of CPAP. If the AHI has decreased to below 15 on a repeat sleep study, CPAP can be continued. However, if the AHI remains at 15 or greater, CPAP should be discontinued.1
Sincerely,
Renaud Tamissier, MD, PhD
*HP2 Laboratory (Hypoxia: Pathophysiology) INSERM U1042; JosephFourierUniversity, Grenoble, France
- Fleetham J, Ayas N, Bradley D, Fitzpatrick M, Oliver T, Morrison D, Ryan F, Series F, Skomro R, Tsai W. Canadian Thoracic Society 2011 guideline update: Diagnosis and treatment of sleep disordered breathing. Can Respir J. 2011 Jan-Feb;18(1):25-47.
