Health News Review

We can’t always accommodate requests that come to us from followers, but when a journalist asked us to analyze a study on yoga and atrial fibrillation, we saw an opening.  Harold Demonaco, MS, one of our story reviewers and active guest bloggers, offers his analysis.

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I should point out that I have a conflict of interest in writing this blog.  My wife is now devoting her time to the study and teaching of yoga.  So, it is with that caveat that you should read on.

Yoga has been demonstrated to reduce high blood pressure, anxiety and symptoms of depression is a number of studies.  While most of the studies were of small sample size and variable design, the total data set suggests an effect when yoga in two of its aspects, poses (AKA asanas) and meditation, are practiced with some routine.  Subjective improvements in quality of life, attitude and ability to manage occasional stressors have also been documented.

Atrial fibrillation is the most common cardiac arrhythmias in adults and has been shown to be an independent risk factor for sudden death in both men and women.  Although many people with atrial fibrillation are relatively asymptomatic, in its more severe forms it can dramatically affect quality of life.  Although we have somewhat improved ways of discontinuing the arrhythmia in people with new onset and in reducing episodes, many patients need to have their heart rate controlled with drugs and must take anticoagulants to prevent stroke.  While some people have continuous runs of the arrhythmia, many experience occasional episodes.  Some of these episodes are obvious to the patient and some are not.  These occasional bouts are of concern.  Going in and out of atrial fibrillation can cause a blood clot to form within the heart chamber and then be released when the heat beat normalizes.

With that as background, it seems quite reasonable for someone to have taken a look at the effectiveness of yoga in reducing episodes of atrial fibrillation.  The arrhythmia is closely attributed to excessive tone in the sympathetic branch of the nervous system (as is for example hypertension).  Yoga has been shown to reduce sympathetic tone and/or increase parasympathetic tone.

Since there is biologic plausibility, I was surprised that the current announcement of completion of a study from the University of Kansas appears to be the first of its kind.  The study is interesting in its design and in it conclusions.  Like every published study, this one has some warts that need to be thought about to put its conclusions into perspective.

The study identified a sample (ultimately a total of 49) of people with atrial fibrillation.  The baseline characteristics of the sample are representative of those with the arrhythmia.  Each subject was followed for 90 days to determine their atrial fibrillation event rate.  Quality of life/anxiety/depression scales were measured at baseline and again at 90 days.  Each subject participated in two-one hour yoga sessions per week with an option for additional practice in the interim.  Baseline data was again collected at the end of the 90 day yoga intervention. The primary outcome measure was the number of episodes of atrial fibrillation pre and post intervention.  The study concluded that the introduction of yoga was associated with a significant reduction in episodes of atrial fibrillation.

The differences, while statistically significant, may not be as important as the phrase would imply.  For those with symptomatic atrial fibrillation, there was a reduction of 0.9 events.  If the events were recorded as daily events, that means that in the control period, these same people were not troubled by the arrhythmia a total of 86 days.  During the yoga intervention, there was a potential increase of one day in the 90 day period.  So, the differences are subtle to say the least.  The same could be said for the improvements in quality of life/anxiety and depression.

The sample size was small and the duration of follow up was relatively short.  An important unanswered question is the durability of the intervention and the drop out rate of people who discontinue the practice of yoga.

Having said all of that the study is interesting and represents a first step toward a better understanding of non-pharmacologic approaches to the treatment of people with this common cardiac arrhythmia.  Changes in systolic blood pressure, a good measure of sympathetic tone correlated with reductions in events and improvements in quality of life.  Hopefully the publication of this study will lead to additional larger studies.

In the meantime, what is the take away message?  Other than the consuming of time and occasional muscle pain, the practice of yoga has few side effects.  The effectiveness of yoga practice in reducing the burden of atrial fibrillation is still unclear but one could argue (as my wife clearly would) that the benefits outweigh the risks.

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Comments

Tom posted on February 1, 2013 at 9:45 am

There’s another take away message. This “study” had no control group, and there is no apparent reason why they could not include one. I think the investigators should be sent back to try again.

Larry Husten posted on February 1, 2013 at 12:24 pm

Of course it’s entirely possible that a similar effect could be achieved with almost any form of exercise/physical activity.

Harold DeMonaco posted on February 1, 2013 at 2:37 pm

A good point and one that I wrestled with. Simply following a control group may or may not be preferable since there are lots of variables that would need to be considered for the control group to be a matched control. I wondered about a longer history than simply 3 months and a longer follow up. However, I could not come up with a better design than the one they chose.

    Tom posted on February 2, 2013 at 9:21 am

    The control group is automatically matched if you randomize, and there was no reason not to do so.

      Doug Mathias posted on February 4, 2013 at 10:54 am

      One could manufacture a de facto control group by examining existing rates and clinical intensities of AF in a general patient population that is not associated specifically with yoga, but which may or may not engage in other forms or relaxation or exercise post-event.