Athletes Have an Increased Risk of AF, Meta-analysis Confirms

Compared with people who are sedentary or only participate in sports recreationally, athletes have a greater risk of developing atrial fibrillation (AF), a meta-analysis in the British Journal of Sports Medicine affirms.

The relationship was more pronounced in athletes younger than 55 and in those participating in sports that mix skill and strength like soccer, basketball, or volleyball than in those partaking in endurance sports like cycling, Nordic skiing, or rowing.

“Our findings of an increased risk of AF in athletes matches our hypothesis based on previous work,” senior author Jamie O’Driscoll, PhD (Canterbury Christ Church University, England), told TCTMD via email. “However, the degree to which the risk is increased (more than double) was perhaps unexpected, as was the chances of AF being greater in mixed sports.”

It’s important to note, however, that athletes had a lower risk of cardiovascular disease, O’Driscoll added.

“There is substantial evidence demonstrating the benefits of physical activity reducing the risk of numerous chronic diseases, such as cardiovascular disease, and that remaining inactive substantially increases the risk of chronic disease,” he said. “What we currently do not know is the exact lifetime hours of exercise or duration of exercise that increases the risk of AF. However, performing exercise in line with current World Health Organization guidelines is safe and recommended.”

Still, athletes, who “tend to know their bodies really well,” need to speak up when they feel any changes that might be indicative of a problem, O’Driscoll indicated.

“Our work highlights that athletes and coaches may need to be educated in the symptoms that are associated with AF (which can include interrupted sleep, fainting episodes, palpitations, and/or a change in the level of breathlessness/tiredness during exercise), so that they can see the importance of seeking appropriate medical advice, evaluation, and/or intervention.”

Support for a J-Shaped Relationship

Prior research has demonstrated that there is a U-shaped relationship between exercise and AF risk, with both a lack of physical activity and long-term vigorous exercise associated with greater risk of developing the arrhythmia.

Two previous meta-analysis explored this issue, with one published in 2009 in EP Europace and one published in 2018 in IJC Heart & Vasculature showing a consistently elevated AF risk in athletes, with the latter indicating that the relationship is stronger in adults younger than 54.

Those meta-analyses, however, excluded studies that included athletes with hypertension or diabetes. This new meta-analysis, with lead author William Newman, MS (Canterbury Christ Church University), “included not only sedentary but also physically active populations, as well as included data on those participants with high blood pressure and diabetes, which are well-known risk factors for cardiovascular disease and AF,” O’Driscoll pointed out. The pooled data set incorporated 6,816 athletes and 63,662 controls from 13 studies (seven cohort and six case-control).

The investigators found that the risk of developing AF was greater in athletes versus controls in the primary analysis (OR 2.46; 95% CI 1.73-3.51), although there indications of significant heterogeneity and publication bias (P < 0.001 for both).

“This work supports that a J-shaped relationship exists, where, in general terms, as you move from no physical activity to performing exercise, your risk of AF decreases; however, as the intensity of exercise increases, there is a point at which the chances of AF increase,” O’Driscoll said.

Additional analyses suggested that the link between athletic participation and AF was confined to populations without CVD risk factors (ie, type 2 diabetes and hypertension) and was stronger in those younger than 55 and in those participating in mixed versus endurance sports. There was not enough information available to examine the impact of exercise intensity.

The investigators note that it is “generally accepted” that there is an association between endurance sports and AF. They suggest that the stronger relationship with mixed sports in this meta-analysis could be related to the fact that studies looking at Nordic skiing—which had the lowest associated AF risk of included endurance sports—accounted for much of the data. “With this, it cannot be excluded that the remaining endurance sports included were comparatively underestimated in the analysis with Nordic skiing over-represented due to a greater quantity of published studies,” they write.

Potential Mechanisms of AF in Athletes vs Nonathletes

Newman et al say that the potential mechanisms linking exercise training to AF “are complex and speculative, but may include atrial dilation, adrenergic activation, vagal tone, chronic inflammation, pulmonary foci, and interstitial fibrosis, occurring as a result of excessive strain through augmented cardiac output and atrial stretch.”

O’Driscoll pointed also to the potential role of triggers like sports supplements or drug use and genetic factors.

Commenting for TCTMD, Martin Halle, MD (Technical University of Munich, Germany), said the pathophysiology of AF may be somewhat similar in athletes and in patients who are obese, for example. Fibrosis associated with the development of the arrhythmia may arise from volume overload during exercise training or from the accumulation of adipose tissue around the sinus node in the right atrium, he explained.

However, the clinical consequences of AF in the two populations are quite different, said Halle, who is president of the European Association of Preventive Cardiology. AF comes with a well-known stroke risk in patients who are obese and sedentary and have other cardiovascular risk factors, he explained, whereas it’s been shown that athletes who develop AF but have no other risk factors do not have a heightened risk of stroke and therefore don’t require chronic anticoagulation. Catheter ablation to treat AF also is more successful in athletes than in nonathletes, he added.

For those reasons, the greater risk of AF is not enough to recommend against athletic participation, although athletes should remain vigilant about the potential complication, Halle said, stressing the importance of incorporating recovery time into any training regimen.

In sports cardiology and exercise physiology, what we emphasize is that strain is good but recovery is also very important. Martin Halle

“In sports cardiology and exercise physiology, what we emphasize is that strain is good but recovery is also very important,” he said. Even Olympic athletes recognize the value of taking breaks, he added, “because this will then increase exercise capacity but will also ensure that pathological mechanisms [like those related to AF] will not develop.”

O’Driscoll noted that in athletes, as in others, “the mainstay of [AF] management is prevention of symptoms, protection from stroke risk, and modification of risk factors.”

He specified, though, that “athletes present unique challenges that require an open dialogue of the evidence behind different treatment strategies and shared decision-making to provide the optimal therapy for a given athlete. Further research is required in this field to better inform guidelines to provide more-superior cardiovascular care for the athletic heart.”