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CATNAP Study
(Melbourne, Australia)
Update - June 2003
Cardiomyopathy, Apnoea and Trial of Nasal Airway Pressure
Darren Mansfield
Claire Gollogly
Peter Bergin
Meroula Richardson
David Kaye
Matthew T Naughton
Dept of Cardiology and Respiratory Medicine Alfred Hospital and Monash
University
This was a randomized controlled trial that recruited patients with a pre-existing diagnosis of cardiomyopathy; either ischaemic or idiopathic in origin. Patients who had a clinical suspicion of obstructive sleep apnoea were invited to participate. The features of obstructive sleep apnoea include: loud heavy snoring; episodic breath holding during sleep at night; unrefreshed sleep and excessive daytime sleepiness. Obstructive sleep apnoea is a condition whereby the throat collapses repeatedly during sleep at night causing the sufferer to choke and momentarily wake from sleep. The episodes of repeated waking cause the patient to feel unrefreshed in the morning and complain of excessive daytime sleepiness.
Sleep apnoea contributes to nocturnal surges in blood pressure and increases sympathetic nerve activity, both of which may lead to a progression of cardiomyopathy. It is estimated that up to 25% of patients with cardiomyopathy may have the co-existence of obstructive sleep apnoea. To date the effect of identifying and treating obstructive sleep apnoea in patients with cardiomyopathy is not known.
We recruited 55 patients with a diagnosis of stable cardiomyopathy and untreated obstructive sleep apnoea. The patients were randomly divided into one of two groups: treatment of sleep apnoea for three months, or observation and conventional heart failure treatment. Treatment of obstructive sleep apnoea was achieved by applying nasal continuous positive airway pressure (CPAP) during sleep. This allows the throat to be expanded by pressurizing the upper airway. This eliminates snoring and choking and has been shown in previous studies to reduce blood pressure and sympathetic nerve activity in such patients.
In this study, we were able to demonstrate that the patients in the CPAP treatment arm had a 30% reduction in sympathetic nerve activity and a 25% improvement in symptoms as assessed by a number of questionnaires. This translated to
improvement in cardiac ejection fraction ( a measure of ventricular contractile force) by 14%.Many of the symptoms of obstructive sleep apnoea are tolerated because the patient believes they are attributed to the underlying cardiomyopathy. This study shows that some of the overall burden of symptoms can be explained by sleep apnoea in some patients. If identified this can lead to substantial gains in sympathetic nerve activity, symptoms and heart function. In addition we would hope that these findings could translate into improved long-term outcomes.
Darren Mansfield
Thanks to Darren Mansfield for giving us
this report on the catnap study.
4 Sep 2002
13 Nov 2000
Latest News from the CATNAP Study
Following an email from Dr Mansfield on 13 November 2000, the CATNAP project is going well.
The study requires 40 volunteers and as of this date has recruited 33. The recruitment process has slowed, however recruiting
will continue until April 2001. Less than 20 volunteers have completed the study so it is still too early to make any comments on the results.Dr Mansfield feels the volunteers involved have enjoyed the study and have got a lot out of it. He says that many of the volunteers appear significantly better off for the treatment of their sleep apnoea.
As a reminder, those wanted for the study are people with the following:
- Snorers(regular)
- Witnessed apnoeas
- Excessive sleepiness
- Obesity.
These are all risk factors or clues to the presence of sleep apnoea.
Thanks to Dr Mansfield for keeping us up-to-date with the progress of this study.
14 Jun 2000
Last updated 13 January 2006 .
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