**EP13: Who Gets Atrial Fibrillation?**
Welcome to Dr. Warwick's podcast channel. Warwick is a practicing cardiologist and author with a passion for improving care by helping patients understand their heart health through education. Warwick believes educated patients get the best health care. Discover and understand the latest approaches and technology in heart care and how this might apply to you or someone you love.
Hi, and welcome to my consulting room. Today I'd like to talk a little bit more about atrial fibrillation. One of the things that people often ask is, who gets it? Well, men and women get it. Men, probably slightly more if you look at the numbers. Women, interestingly, when they suffer the condition, run a higher risk of complication. So although more men in numbers actually suffer with atrial fibrillation, women have a higher rate of complication and therefore are impacted equally. This is particularly the case as people get older because one of the things that we see with atrial fibrillation is an increasing incidence of the condition as people age.
We do see a genetic predisposition, and there are certain families where a genetic link can have a significant upregulation of the likelihood of someone within their family developing the condition. This is not the most common situation, but it certainly is important to be aware of. When we think about the things that are likely to increase the likelihood of atrial fibrillation, we can think of etiologies or causes that impact the structure and function of the atrium.
Simple things like high blood pressure, where the back pressure has a stretching effect on the atrium over time, will change the shape of the atrium. By changing the shape of the atrium, it increases the likelihood of developing an abnormal rhythm within it. The change of shape is often associated with scarring—microscopic scarring nonetheless—but scarring that then alters the way that electricity flows through the atrium and again starts to push that risk of developing atrial fibrillation up.
So, age with a little bit of micro scarring, general wear and tear with time, and high blood pressure leading to pressures affecting the atrium are all contributing factors. The valves being abnormal can also have an effect on the pressures within the heart, and so abnormalities of the valves and how they work can lead to back pressures that again impact on the atrium and therefore the structure and subsequently the function.
Of course, things like cardiac failure or abnormalities of the muscle of the heart can also be implicated and associated with an increased likelihood of developing atrial fibrillation. We can also think of things that cause atrial fibrillation in the context of external factors, or things outside the heart that impact the heart.
It turns out things like diabetes over the long term seem to impact the heart, possibly with byproducts of diabetic metabolism ending up within the structure and the fibers of the myocardium, therefore impacting how the atria and the muscles work. We see that obesity is linked with an increased likelihood of atrial fibrillation, and obesity together with obstructive sleep apnea—a condition where people obstruct their respiratory system at night while they're asleep and really suffer with low levels of oxygen overnight—can trigger a very brisk response of the autonomic nervous system.
So, the body is heightened, although the person is asleep, which can increase blood pressure and drive scarring and inflammation within the heart, again all contributing to the possibility of developing atrial fibrillation. We see that people with bad kidney function over a period of time have a high propensity to develop atrial fibrillation. Nearly 20% of people with chronic renal disease will develop the condition, and this is a complication of multiple things: elevated blood pressure, inflammation, and a general propensity to scarring and change within the heart.
We also know that external toxins, and probably the most common is alcohol, can raise the likelihood of development of atrial fibrillation. So, a boozy night out with a lot of snoring and bad sleep is exactly the sort of thing that could trigger off enough electrical activity within the heart to kick off an episode of atrial fibrillation. In fact, we do see it not uncommonly that people will turn up on a Monday morning with a Saturday night arrhythmia from exactly that.
We see other stresses on the heart also have an effect on the likelihood of atrial fibrillation being present or being precipitated. Such things as surgery—whether it be bowel surgery, but of course very commonly any surgery on the heart where the atrium are actually manhandled and touched during the process—markedly increase the risk of development of atrial fibrillation, as you'd expect. Infections can do it; a severe pneumonia, a severe infection of any sort, in fact, because the body is responding in such a way that extra adrenaline and extra nervous activity are all being generated, and that can increase the likelihood of abnormal rhythm within the heart, particularly atrial fibrillation.
We know that other conditions, such as pancreatitis, for example, could also lead to atrial fibrillation. So, anything within the body that can really increase what we call the autonomic nervous system, which is the fight or flight nervous system, can kick off an episode of atrial fibrillation. Lastly, and really importantly, emotional stress can do it as well. It is not uncommon for me to see patients who, for various reasons, have had a significant emotional impact, whatever that might be, and they've literally felt that in their heart, with their heart jumping and fluttering. That emotional stressor has been the precipitant for atrial fibrillation to kick off in that individual.
So, what can we do? Well, age we cannot avoid. It will lower our threshold to development of atrial fibrillation, no matter what. So age is one that we can do little about. But things like blood pressure, weight control, good sleep, not too much alcohol, not too much emotional stress, and being aware of where atrial fibrillation can occur is a really important first step.
One of the areas where atrial fibrillation occurs, which is really surprising, so I've left it to the end, is that we can sometimes see it in endurance athletes. We know that exercise in general is very good for our health, and in fact, we know that normal levels of exercise—moderate, on a weekly basis, several times a week—will lower our risk of coronary artery disease, lower our risk of heart-related illness, and in fact lower our risk of atrial fibrillation.
However, in a specific subset of athletes who train for endurance events, long protracted training sessions and long events, these people have been shown for multiple reasons to run a higher risk of atrial fibrillation in the longer term. This is possibly related to that endurance activity leading to significant stress on the heart with return of blood that acts as its own impact on the chambers of the heart, leading to dilatation and compensation of the heart.
That long-term exercise seems, together with a change in the neurological way that the heart responds—with a tendency towards the parasympathetic nervous system, which is the opposite of the sympathetic nervous system—seems to lower the threshold for development of atrial fibrillation. And so, quite surprisingly, the last group is a group of people who are actually very well-trained athletes.
Be aware, and I hope that all makes sense. Thank you very much for your time. You have been listening to another podcast from Dr. Warwick. Visit his website at drwarwickbishop.com for the latest news on heart disease. If you love this podcast, feel free to leave us a review.
