Author + information
- Christoph Stellbrink, MD* (, )
- Erik Skobel, MD and
- Anil-Martin Sinha, MD
- ↵*Medizinische Klinik I, University Hospital, RWTH Aachen, Pauwelsstrasse 30, D-52074 Aachen, Germany
We thank Dr. Scharf and colleagues for their valuable comments to our study on central sleep apnea (CSA) and cardiac resynchronization therapy (CRT) (1). Importantly, all patients in our study had CSA and no evidence of obstructive sleep apnea (OSA). Because apnea occurred with a periodic pattern in patients with known advanced heart failure we believe that the breathing pattern can be classified as CSA although timing of arousals relative to respiratory events could not be evaluated with the polygraphy system used. We agree that desaturation index, breathing cycle length, and time in apnea add important information and have summarized these data in Table 1.
We have now studied more patients with mixed apnea or OSA and found less improvement in mixed apnea and no significant effect in OSA (2). Therefore, we believe that CRT works mainly on CSA by improving cardiac hemodynamics.
The notion that CSA is related to the severity of heart failure was derived from previous studies (3) and not from our data. We caution that our results refer to a small group of patients with short follow-up. Differences in functional response between CSA and non-CSA patients may only become evident later or in larger patient cohorts. The studies on posttransplant patients (4,5) had longer follow-up times but also showed similar improvement in both CSA and non-CSA patients. The effect of CRT on CSA in our study seemed larger than in these studies, which may be explained by the fact that OSA patients were not included and new OSA was not observed in our patients during CRT. It is yet unclear why OSA develops in some patients after cardiac transplantation.
Finally, all our patients had ventricular conduction disturbance, which qualified them for CRT. The incidence of ventricular conduction disturbance has not been reported in previous trials on CSA. The association of CSA and cardiac rhythm disturbances such as atrial fibrillation has recently gained interest (6). We hope that our data may stimulate further research into this direction.
- American College of Cardiology Foundation
- Sinha A.M.,
- Skobel E.C.,
- Breithardt O.A.,
- et al.
- ↵Skobel E, Sinha AM, Norra C, et al. Effect of CRT on sleep quality, quality of life, depression and respiratory patterns in patients with chronic heart failure and sleep-related breathing disorders (abstr). Eur Heart J 2004; CD-ROM: P3380.
- Lanfranchi P.A.,
- Braghiroli A.,
- Bosimini E.,
- et al.
- Gami A.S.,
- Pressman G.,
- Caples S.M.,
- et al.