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Former NFL players at great risk for AF
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Retired National Football League players were more than five times as likely to have atrial fibrillation compared with men in the general population, according to findings published in the Journal of the American Heart Association.
Dermot Phelan, MD, PhD, director of the Sports Cardiology Center at Cleveland Clinic, and colleagues conducted a cross-sectional study comparing AF prevalence in retired NFL players (n = 460; mean age, 56 years; 47% black) with that in men from the Dallas Heart Study-2 (n = 925; mean age, 54 years; 53% black). The groups were propensity-matched based on age and race.
“We know that endurance athletes who participate in long-term endurance sports at a very high level are at increased risk of atrial fibrillation,” Phelan told Cardiology Today. “The question arose as to whether this held true for more strength-style sports. We had the opportunity to do 10 screening events with the NFL Player Care Foundation to find out.”
Presence of AF was documented in 5% of the NFL cohort and in 0.5% of controls.
Elevated AF risk
When the researchers conducted a multivariate regression analysis to control for CV risk factors, they found that past participation in the NFL was associated with more than fivefold odds of AF compared with controls (OR = 5.7; 95% CI, 2.1-15.9).
“It was surprising that we saw the same amount of atrial fibrillation in strength-style athletes compared with endurance athletes because the stresses on the heart are very different,” Phelan said in an interview. “Although this study was not designed to determine what the mechanism of atrial fibrillation was, we suspect the mechanism is different between strength-style athletes vs. endurance-style athletes.”
Also associated with increased odds of AF were older age, nonblack race and higher BMI, but not hypertension or diabetes.
Of the 23 former NFL players who had AF, the condition was undiagnosed in 15 of them, according to the researchers, who noted that among those undiagnosed, all were asymptomatic and rate-controlled, but 80% had a CHA2DS2-VASc score of at least 1. Resting heart rate was lower in the NFL group (62 beats per minute vs. 66 bpm; P < .001), according to the researchers.
Compared with controls, the NFL group was more likely to have paced cardiac rhythms (2% vs. 0.25%; P < .01) and first-degree atrioventricular block (18% vs. 9%; P < .001), Phelan and colleagues wrote.
AF despite lack of risk factors
“We saw such an increased risk of atrial fibrillation in the NFL cohort despite the fact they had lower rates of known risk factors for atrial fibrillation such as high blood pressure and diabetes,” Phelan told Cardiology Today. “We also saw slower impulse formations, so the heart rates were a little slower in the NFL group, and slower propagation of the impulse through the heart. We see that in other types of athletes also. We think the reason why so many of these players were asymptomatic was because the heart rate while they were in atrial fibrillation was well controlled. Yet, the majority of them should have been taking anticoagulation to prevent stroke.”
Future research should explore whether the findings are unique to the NFL or are also applicable to other strength-style athletes, Phelan said. – by Erik Swain
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Matthew W. Martinez, MD
The sports cardiology community continues to develop best practices for evaluation of athletes pre sport (screening), management of CV risk during sport (emergency action plans and automated external defibrillator preparation), and now we are seeing more data on the long-term health of former elite athletes. These data, although observational, add to that knowledge. With observational data, we cannot conclude a definite cause and effect, but the data does provide further knowledge. Does prolonged strength training lead to arrhythmias such as AF? Previous studies have linked long-term participation in endurance sports such as cycling and marathon running with an increased risk for AF. This is the first study to suggest a link to a non-endurance type sport.
The mechanism is unclear. Is this related to obesity, changes in systolic BP, sleep-disordered breathing, non-steroidal anti-inflammatory drug use or performance products? How much playing time is enough to incur risk — high school, collegiate or professional? Is this level of intensity or duration enough to incur risk? If we believe this to be strength-training related, are body builders or powerlifters at risk? More data are needed for all those questions.
AF is traditionally associated with hypertension, obesity and sleep apnea. It would be helpful to know the association of those risk factors with AF risk in this group. NFL athletes are bigger than in prior decades. Are we seeing the CV risks associated with being that size? Is this related to a group at higher risk for development of hypertension and sleep-disordered breathing as they get older?
Concerns regarding the impact of American-style football on CV health has now led to several observational findings. These include cardiac risk and pathologic CV phenotypes, particularly amongst lineman‐position players. Although the impact and causality is still a work in progress, the findings on long‐term health outcomes in this group are growing. Development of risk stratification and algorithms are needed to improve clinical outcomes in this population.
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