Sleep apnoea and AF- the importance of RCTs

If you want some background, our June article "What is Sleep Apnoea and why does it matter in AF?" nicely explains what obstructive sleep apnoea (OSA) is and that it's commonly found in individuals with AF.

The reason we're doubling back on this topic is because:

it affects up to 50% of patients with AF- often undiagnosed.
Researchers in Norway have published a randomised controlled trial that goes one step further- to determine whether the treatment of sleep apnoea impacts outcome after AF ablation.

Randomised controlled studies are the gold standard scientific way to answer questions like this because it balances outside factors that can influence the outcome. CPAP is a highly effective treatment for OSA that controls symptoms, improves the quality of life, and reverses the clinical sequelae of the condition. AF treatment is less effective in patients with OSA and more likely to relapse. Therefore the rationale is that treating the OSA will improve the outcome after AF treatment.

The researchers recruited 83 patients with paroxysmal (on and off) AF and sleep apnoea and randomly allocated half the patients to receive 5-months of CPAP therapy before their ablation and then for 12-months after. The other half continued with standard care only. AF ablation significantly reduced the total AF burden but when you compare the relative outcome at 12-months after the ablation there was no significant difference in the rate of AF recurrence, total AF burden or the reported quality of life between the two groups.

The lines represent the number of patients in each group that remain free of AF. The red line represents patients in the active arm who received CPAP treatment and the blue line are the patients in the standard care arm. The green line are patients without OSA who were also monitored.

The direct implications of this study are important. To date, the evidence does not suggest that treating OSA will significantly alter the outcome after AF catheter ablation. (*note CPAP is still a highly effective treatment for OSA and so if you have OSA, it is absolutely worth considering from this perspective*). The indirect implications of this result are also important- to make assumptions in clinical practice is wrong, and pursuing randomised trials to establish a strong evidence-base for decision-making is essential.

There are many examples where we have seen randomised controlled studies reverse prevailing beliefs based on observational studies. Most recently we saw this during Covid-19; during the first-wave, many people including scientists and doctors were convinced of the therapeutic value of treatments like hydroxychloroquine or ivermectin. There was frustration and anger in some communities that it wasn't more widely prescribed. However, the results of the randomised controlled RECOVERY trial were clear; there was no benefit from these treatments and they should not be used for Covid-19.

This is why research studies like the AFHF study, the AFFU-AW study, the CSAF-AW study and the many others being performed at Barts and beyond are so important.

to make assumptions in clinical practice is wrong, pursuing randomised trials and establishing a strong evidence-base for decision-making is important

A neutral or negative result is important because it helps to re-frame our perspective on the issue- perhaps OSA is simply a bystander, meaning it isn't a cause of worse outcomes but it too is a result of a deeper disease process that causes AF progression and OSA and we need to identify and target this. Alternatively, this is just one small randomised study and there may, in fact, be value in CPAP treatment for AF and it just wasn't detected here.

So, to go back to the topic at hand and summarise, patients with OSA have a worse outcome after AF ablation however CPAP treatment has not been shown to significantly affect AF-related outcomes and further studies are warranted.

Hunt TE, Traaen GM, Aakerøy L, Bendz C, Øverland B, Akre H, Steinshamn S, Loennechen JP, Hegbom F, Broch K, Lie ØH, Lyseggen E, Haugaa KH, Gullestad L, Anfinsen OG. Effect of continuous positive airway pressure therapy on recurrence of atrial fibrillation after pulmonary vein isolation in patients with obstructive sleep apnea: A randomized controlled trial. Heart Rhythm. 2022 Sep;19(9):1433-1441. doi: 10.1016/j.hrthm.2022.06.016. Epub 2022 Jun 16. PMID: 35716856.