Atrial Fibrillation in endurance athletes

Consider this a public service announcement.

I just read this comment on another blog:

My Polar is going haywire at the moment, with my heart rate suddenly shooting up to an unhealthy 230 for no reason at all. It even plays with my emotions by occasionally being close to what I’d expect, but not quite (popping up 10 bpm then quickly shooting back down, for example), giving me a sense of insecurity about my hill-climbing prowess, or lack thereof.

The commenter thinks that his Polar Heart monitor is having a problem. When I saw that description, I wondered whether he is having an episode of atrial fibrillation (A-fib). 

Middle age male endurance athletes - marathoners, ultracyclists, cross country skiers - have a higher incidence of atrial fibrillation than the general population. This ironic anomaly has been well documented in numerous studies. (Just Google "Atrial Fibrillation endurance athletes"). There is also informative post on the topic at Road Bike Rider by a chiropractor and cyclist  (Link).

While the author of the linked article had a very noticeable presentation of symptoms, the signs of AFib can also be very subtle and easily overlooked, especially by endurance athletes who are used to overlooking things like feeling tired, lethargic and having an elevated heart rate because they chalk them up to the effects of hard training. Most times these symptoms will be for that reason, but that is not always the case. I know of one person whose only real warning came from erratic readings on a heart rate monitor - very similar readings to what the blog commenter described. (That person did have other symptoms but none that seemed related or were significant enough to get his attention before the diagnosis.)

A-fib is treatable, correctable and even curable under the right circumstances, but left untreated, it can lead to a stroke. It is also easily diagnosed by a doctor, if they have the opportunity to examine you.

The purpose of this post is not to describe all of the symptoms or give a diagnosis - I am not a doctor - I just want to put this idea on your radar. The general age, gender  and lifestyle of most Randonneurs fits perfectly with the population that should be aware of this condition. So be aware of it, for yourself and for your fellow riders. Maybe this post will help someone figure out something that can save their life.

June 13, 2012 UPDATE:

Dean Furbish (a commenter to this post) has a  blogpost on this and related topics. You can find it here. Thanks Dean.