Severe Obstructive Sleep Apnea Predicts Atrial Fibrillation Ablation Failure, New Study Says

July 6, 2010 8:05 AM CT

By Peggy Noonan and Mellanie True Hills

Roughly half of those who have obstructive sleep apnea (OSA) also have atrial fibrillation (AF). In obstructive sleep apnea, the airway becomes blocked during sleep, which causes interruptions in breathing.

Although research hasn’t confirmed obstructive sleep apnea as a cause of atrial fibrillation, studies have shown that afib recurrence is higher following electrical cardioversion (using electricity to convert atrial fibrillation to normal rhythm) in those whose sleep apnea has not been treated. Research has also shown that afib improves when sleep apnea is treated using Continuous Positive Airway Pressure (CPAP) machines.

Now we have more information about sleep apnea and atrial fibrillation thanks to a new study from Spain. Doctors followed 174 people aged 18 to 75 who had been treated with a single catheter ablation for their symptomatic atrial fibrillation (afib that they could feel).

All 174 participants completed the Berlin Questionnaire (BQ), a validated tool that researchers use to identify people who have obstructive sleep apnea. It asks questions about apnea-related issues, such as snoring, daytime sleepiness, high blood pressure, and body mass index (BMI), a gauge of obesity.

The questionnaire indicated that 51 (29.3%) of the 174 were at high risk for obstructive sleep apnea, and of those 51 who underwent sleep studies, 17 were diagnosed with non-severe sleep apnea and 25 with severe sleep apnea.

The researchers also observed that “obstructive sleep apnea patients had slightly larger left ventricular dimensions and larger body mass index” than those who did not have sleep apnea, and they also had more high blood pressure and structural heart disease.

Follow-up outpatient visits and 24- or 48-hour Holter monitor tests were done at one, four, and seven months after ablation, and then every six months for those who remained free of symptoms. 

The goal of this study was freedom from any documented episode of AF or atrial flutter lasting 30 seconds or more after a single ablation and without any antiarrhythmic (rhythm control) drugs.

Among those who had a single catheter ablation and were not on antiarrhythmic medicines, the following percentages were arrhythmia-free after one-year:

  • 48% of those at low risk for sleep apnea
  • 30.4% of the non-severe sleep apnea group
  • 14.3% of the severe sleep apnea group

Of those who had a second ablation, 39 (29.5% of the group) were in the group at low-risk for obstructive sleep apnea, 8 (47.1%) were in the non-severe sleep apnea group, and 11 (44.0%) were in the severe sleep apnea group. “Overall, the arrhythmia-free proportion at 1-year follow-up in the present series was 68.8%, 43.8%, and 14.3% respectively, including a second procedure as warranted,” say the study authors.

Most arrhythmia recurrences happened in the first six months and were significantly higher in people who had severe obstructive sleep apnea. The authors also note that left atrial diameter and severe obstructive sleep apnea were predictors of arrhythmia recurrence after a single ablation.

What the Results Mean

“The results of the study suggest that the presence of severe OSA is a powerful predictor of ablation failure, independently of atrial enlargement, obesity, or hypertension that may co-exist in OSA patients,” the researchers conclude.

Why? That’s not clear yet. They speculate that “one possibility could be the presence of AF triggers outside the PVs [pulmonary veins] and LA [left atrium]”, and it is reasonable to assume that atrial fibrillation in obstructive sleep apnea is not related to PV firing, as it is in other forms of afib, and that it may be related to the presence of a more extensive arrhythmic substrate, the underlying heart tissue that initiates afib.

Nine of the participants at high risk for obstructive sleep apnea were treated with CPAP before and after ablation, but their ablation success didn’t differ from the untreated patients in the same group. With such a small number of people studied, it’s impossible to draw any definite conclusion, but the researchers say this suggests that “once the damage to the atrium is established, CPAP cannot restore stable rhythm” and “this fact, together with previous observations suggesting a positive effect of CPAP in early stages, would favor earlier detection and treatment of OSA in AF patients.”  

Also, they note it’s possible that some patients might have been misclassified in the low-risk group and did not undergo sleep studies—only those that the questionnaire identified as having obstructive sleep apnea completed a sleep study. 

We’ll need further studies to clarify these points and learn more about the role of obstructive sleep apnea in afib recurrence following ablation. Until then, the researchers say, “Severe OSA is an independent predictor for low probability of AF ablation success in terms of arrhythmia recurrence.”

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Mellanie’s Comments:

The findings of this study are quite concerning since many doctors don’t yet know to ask their afib patients about sleep apnea. That’s one reason for you to bring it up.

Since the researchers suggest that sleep apnea may be related to triggers in places other than the pulmonary veins, and since this study suggests that the longer one has sleep apnea the less likely ablation is to be successful, that leads to questioning whether sleep apnea is causing fibrosis and remodeling throughout the atrium that makes success less likely.

These results suggest that we need to get tested and treated for sleep apnea early, and that ablation might be more likely to be successful in the early stages of sleep apnea treatment. Thus, this is just one more reason to be concerned about the suggestion to take a “wait and see” approach.

But for those who have had sleep apnea for a while, it’s not hopeless. In the video interview below, Dr. Jackman talked about how treating the “third fat pad” during a procedure—either surgery or catheter ablation—can help with sleep apnea.

Peggy Noonan specializes in writing about health for consumers and medical professionals. She writes for leading national magazines and consumer publications as well as StopAfib.org.

Mellanie True Hills is founder and CEO of StopAfib.org and an atrial fibrillation survivor.