Treating a common sleep-related breathing condition almost halved the chance of recurrent atrial fibrillation (AF, see Definitions). However, most of the included studies were observational. This makes it difficult to rule out the possibility of bias in choosing which patients to treat and therefore reduces our confidence in the size of this effect. The breathing condition - obstructive sleep apnoea (see Definitions) - has often been found in association with AF.
This review aimed to see whether a recommended treatment for people with obstructive sleep apnoea, continuous positive airway pressure (CPAP, see Definitions) might reduce the risk of AF recurring in those with the condition.
The study did not address the cost implications of diagnosing or treating obstructive sleep apnoea, which could be high, particularly if considering screening people with sleep disordered breathing for AF. Neither did it look at the acceptability of wearing a CPAP device at night. Other reviews have found that some people find this treatment uncomfortable and don’t persist with it.
Further high quality evidence, economic analysis and service reorganisation are needed before this could enter common practice in the NHS.
Why was this study needed?
Obstructive sleep apnoea is thought to affect up to 4% of middle-aged men and 2% of middle-aged women in the UK. The condition has been found in association with AF, the most common type of heart rhythm abnormality, which affects around 2% of people in the UK. Previous research has suggested that people with obstructive sleep apnoea are six times as likely to have AF as the general population, and those with AF are more than twice as likely to have obstructive sleep apnoea. The reasons for the link are incompletely understood.
It is thought that obstructive sleep apnoea is under-diagnosed in people with recurrent AF and that by improved detection the treatment of recurrent AF could be improved.
The aim of this review was to determine whether using CPAP to treat people with obstructive sleep apnoea and recurrent AF after a catheter ablation (see Definitions), could reduce the chances of AF recurring. AF recurs in about a quarter to two thirds of cases within 5 years of an ablation or cardioversion (see Definitions).
What did this study do?
This systematic review included eight studies including 1,247 adults with obstructive sleep apnoea who had been treated for AF by catheter ablation. Of these people 698 had used CPAP and 549 were non-users. The researchers compared risk of AF recurrence between the two groups of people.
The review met reporting standards and assessed quality of included studies using Cochrane guidelines. However, most of the studies included less than 200 participants, and only one of the eight studies was a randomised controlled trial (of low quality), the rest were cohort studies. Observational studies cannot provide such robust evidence as randomised controlled trials because patient characteristics may have influenced the decision to use CPAP or not, and may also influence risk of AF recurrence.
The review did not address patient preferences or experiences of using CPAP.
What did it find?
- Across the eight studies, AF recurred in 18% of those who used CPAP and 37% of those who did not. This meant that CPAP was associated with 44% reduced risk of AF (pooled relative risk [RR] 0.56, 95% confidence interval [CI] 0.47 to 0.68). The duration of follow-up for outcome assessment was unclear.
- Analysis taking into account various other patient factors did not find that age, gender, body mass index, high blood pressure or diabetes had a significant influence on the risk of AF recurrence.
- Based on the results from these studies, the researchers estimate that CPAP use in people with obstructive sleep apnoea who have been treated for AF may prevent 17% of them from getting AF recurrence.
What does current guidance say on this issue?
NICE guidance from 2008 recommends using CPAP treatment for people with moderate to severe obstructive sleep apnoea. There is no guidance on identifying AF in people with obstructive sleep apnoea, or recommendations for treatment approach in these people.
What are the implications?
This review found that use of CPAP in people with obstructive sleep apnoea who have been treated by catheter ablation for recurrent atrial fibrillation was linked with reduced risk of recurrence. However, the observational design of most of the included studies limits the applicability of the findings.
The reasons underlying the association between obstructive sleep apnoea and atrial fibrillation are not clearly understood. The reviewers did not find that the variables they examined had an influence on the outcome, but noted that the patient groups were variable and information on severity was not available. There remains the possibility that patient characteristics have influenced treatment decisions.
Other practical implications relate to acceptability and cost. There was no assessment of how acceptable the participants found CPAP. Poor acceptability of the treatment has been highlighted as a major problem in previous reliable Cochrane reviews. There was also no economic evaluation. The authors noted that health services are not configured to look for and treat both conditions at the same time. The cost implications from specialist diagnosis of obstructive sleep apnoea and subsequent CPAP treatment – particularly if considering screening people with AF for the condition – are likely to be high.
Overall, though the findings seem promising, further research into the link is needed before considering changing guideline recommendations. Service reorganisation would be required before translating the findings to practice.
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