Former National Football League (NFL) players have significantly larger aortas than similarly aged men in the general population, potentially putting them at higher risk for aortic rupture or dissection, according to research presented Nov. 29 at RSNA 2017 and published online in Circulation: Cardiovascular Imaging.
Nearly 30 percent of former NFL athletes met the threshold for an enlarged aorta—ascending aortic diameter of at least 40 millimeters measured via CT—compared to 8.6 percent of the control group. The ex-players had an average aortic diameter of 38 mm, compared to 34 mm for non-NFL participants.
“There have been prior studies that have shown elite athletes have slightly larger aortas during their active participation in the sport, but no one has looked at downstream, does that remain?” study co-author Christopher D. Maroules, MD, told Health Imaging. “What we showed was that this is certainly an established thing that progresses into adulthood post-NFL career.
“Is there anything in between active participation and downstream that’s influencing that further? We don’t know, but it does appear that it’s not regressing. … It kind of makes sense because physiologically, when you dilate something you’re kind of weakening the wall of the vessel, so it would be unusual for that to be a reversible process.”
Maroules and colleagues compared 206 former NFL athletes to 759 men from the Dallas Heart Study who were at least 40 years old and had a body mass index (BMI) of at least 20. The ex-athletes were older on average (57.1 years vs. 53.6 years) with greater BMIs (32.4 vs. 30) and more body surface area (2.4 square meters vs. 2.1 m2). Both groups were well-matched racially.
But even after adjusting for size, age and other factors, the researchers found former NFL players were twice as likely to have ascending aortic diameters of 40 mm or more. Because coronary artery calcium scores were similar between the two groups, the differences in aortic dilation were likely not associated with atherosclerotic cardiovascular disease, Maroules said.
In addition, the researchers found athletes who played the positions traditionally occupied by the largest men had wider aortas. Ex-players were divided into “linemen” and “non-linemen” categories. Linebackers joined actual linemen in the “linemen” group, while typically smaller players like ball carriers, kickers and punters comprised the “non-linemen” group.
“I think this study is really just scratching the surface to the whole idea of cardiovascular remodeling among athletes,” Maroules said. “I think what the data are showing and what the study is sort of showing is that strength training may lead to this phenomenon, especially given the observation that linemen tend to have this more than non-linemen—larger patients doing heavy lifting over time. We know that actually does cause concentric remodeling of the heart, so it stands to reason that the proximal aorta should dilate over time with that.”
Maroules said it would be useful to study weightlifters, bodybuilders and elite athletes from other sports and compare the results. He cited previous research showing that as the size of the aorta is increased beyond 40 mm, the risk of aortic rupture and aortic dissection incrementally rises—with a dramatic rise after 60 mm.
“We don’t know if these athletes will be trending toward that 6(-centimeter) mark,” he said. “Anecdotally, I don’t think there have been a lot of reported cases of former elite athletes dying from aortic rupture, but is it something that we should be following and are we doing the sport service by not recognizing that this is a risk factor?”
Because of the small number of ex-athletes in the study, Maroules cautioned it should be interpreted as “hypothesis-generating.” And it is important to note the larger aortic diameters haven’t been associated with increased rates of adverse events at this stage, although Maroules said his research group plans to follow these athletes over time.
“I think it’s a little too early to build up a lot of anxiety about this issue, but I think as an imaging community we need to make sure that we are identifying dilated aortas and we’re following these patients at least annually,” he said.
In an associated editorial in Circulation: Cardiovascular Imaging, Timothy W. Churchill, MD, and Aaron L. Baggish, MD—two cardiologists with the Cardiovascular Performance Program at Massachusetts General Hospital in Boston—echoed Maroules’ suggestion for similar research of older athletes from other sports.
“Further study of their nuanced aortic physiology and pathology will deepen our understanding of the relationship between sport and health not just among these former warriors of the gridiron but also across highly active people and dedicated exercisers of all shapes and sizes,” they wrote.
Because the ex-NFL players in the study were, on average, more than 20 years removed from their playing days, Baggish and Churchill speculated aortic dilation may develop in football players after retirement because of continued high-intensity static activity, health issues related to obesity and hypertension and continued dilation resulting from an injury during a player’s career.