DALLAS, Texas (WPVI) -- According to a new study, former NFL players are nearly 6 times more likely to suffer from atrial fibrillation compared to other men of their age who didn't play pro ball.
The new research was published in the Journal of the American Heart Association, the Open Access Journal of the American Heart Association/American Stroke Association.
Atrial fibrillation, a type of irregular heartbeat that increases stroke risk, occurs when the electrical impulses that initiate each heartbeat fire erratically, causing the atria - the top chambers of the heart - to quiver.
This can result in blood pooling and clotting in the atria.
The clots can travel to a blood vessel leading to the brain and cause a stroke.
5 % of former NFL players had AFib compared to 0.5 % of men in the control group.
80 per cent of the former NFL players with Afib felt no outward symptoms - so they need closer monitoring.
"The heart rate was a little bit slower and so they didn't actually get the tachycardia, or the fast heart rates, that we normally see with atrial fibrillation and therefore they did not have any symptoms and so, this is why we need to be a little bit more vigilant," says lead researcher Dr. Dermot Phelan of the Sports Cardiology Center at the Cleveland Clinic.
Those former players should have been taking blood thinners to lower their stroke risk.
Former NFL athletes were 8 times more likely to have pacemakers compared to the control group. Pacemakers are devices that are implanted in a person's chest, usually to treat slow heart rates and other problems of electrical conduction in the heart.
Despite the higher incidents of atrial fibrillation, the players group had overall lower risk factors for cardiovascular disease mortality, type 2 diabetes and high blood pressure, and had lower resting heart rates compared to the control group.
Dr. Phelan offered a theory on the higher Afib rate.
"Although the study was observational, which means it identifies a relationship but does not prove cause and effect, the prolonged strength training involved in American football may increase heart chamber size and wall thickness, which can alter heart rhythms and electrical signals in the heart," he notes.
Past studies have shown higher A-fib rates among endurance athletes, such as marathon runners, however, this is the first to show a similar risk in strength athletes.
Dr. Phelan says the study shouldn't discourage anyone from being physically active,
"Mild to moderate exercise reduces the risk of atrial fibrillation for most people," he says.
NFL retirees face 6 times rate of Afib as other men