Cleveland Clinic researchers found that a group of retired National Football League (NFL) players were more than five times as likely to have atrial fibrillation (AFib) when compared to men in the general population.
For the first time, Cleveland Clinic researchers show the effects of long-term cardiac conduction in strength-type sports. Previous research has shown correlation between cardiac conduction and endurance-type sports.
The study – published today in Journal of American Heart Association Report – found that a group of 460 retired NFL players were more than five-times as likely to have AFib compared to a control group of more than 900 men.
The study compared a self-selected sample of former NFL athletes to a presumed non-elite athletic control group from the Dallas Heart Study-2. Eighty percent of the NFL players diagnosed with AFib during the study did not show symptoms and didn’t know they had it, but should have been taking medication to reduce their stroke risk. In this study, former players with AFib were older, larger, more inactive and were more likely to be Caucasian. All participants in the DHS had previously known AFib.
The clinical significance of these findings is unknown and will require further evaluation, researchers said, though atrial fibrillation is associated with an increased risk of stroke, heart failure and even death.
When comparing the two groups, the retired NFL players had lower prevalence of cardiovascular risk factors, including type-2 diabetes and high blood pressure. Despite having lower resting heart rates, retired NFL athletes were eight-times more likely of having paced cardiac rhythms.
“We found with retired NFL players, their heart rate was a little bit slower, so they actually didn’t get tachycardia or fast heart rates, that are typically seen with atrial fibrillation,” said Dermot Phelan, M.D., Ph.D., director of Cleveland Clinic’s sports cardiology center and senior author on the paper. “Our study shows we should be a bit more vigilant with this particular population.”
According the American Heart Association, more than 2.7 million people are living with atrial fibrillation. AFib is the most common irregular heart rhythm, where the heart is beating at a rapid rate causing it never correctly fill up with enough blood to supply out to the body. Atrial fibrillation is associated with an increased risk of stroke, heart failure and even death.
The NFL players in the study were broken down into two groups – linemen (tackles, guards, centers, defensive tackles, defensive ends, or linebackers) and non-lineman (quarterbacks, running backs, wide receivers, tight ends, cornerbacks, safeties, kickers or punters). The study showed no difference between the groups.
Researchers outlined some of the study’s limitations: the findings are specific to a small select group of former NFL athletes with the potential for selection bias and which may not reflect the entire former NFL population. Given the relatively small number of former athletes involved, this data should be considered hypothesis-generating and will hopefully result in longer term studies in a wider population of athletes.
Study participants were selected from a group of 484 retired players who participated in a voluntary cardiovascular screening program run by Cleveland Clinic under the auspices of the NFL Player Care Foundation Healthy Body and Mind Screening Program between January 2014 and January 2015. Players were screened for cardiovascular history questionnaire, height, weight, blood pressure, lipid profile and were offered ECG and an echocardiogram. The Dallas Heart Study included a group of people from Dallas County as the control group. The Dallas Heart Study is a probability-based cohort population study of 3,072 adults, who were enrolled from 2000 to 2002. The second phase, DHS-2, of the study was conducted from 2007 to 2009 and followed up with 2,485 participants. DHS-2 was chosen because the cohort was better matched for age with the NFL group.