Former NFL players are twice as likely to have enlarged aortas than the general public, according to a new study. But even the researchers admit they’re not sure whether the condition actually poses a health risk to the retired athletes.

The study screened former NFL players in 10 major cities and measured the size of each person’s aorta, the main artery that supplies blood from the heart to the rest of the body.

Overall, the former football players had significantly larger aortas – nearly 12 percent bigger – than those in a general population control sample.

“Whether this translates to an increased risk is unknown and requires further evaluation,” according to the study published Thursday in Circulation: Cardiovascular Imaging.

Normal aortic size depends on the person’s gender, size and age, but Dermot Phelan, M.D., Ph.D., the study’s lead author, said men generally have aortas that measure less than 38 millimeters.

His study, however, found that 30 percent of the former NFL players had aortas larger than 40 millimeters, the “arbitrary cutoff used clinically and in practice guidelines to define aortic enlargement,” Phelan said. Less than 9 percent of people in the control group had an aorta larger than 40 millimeters.

“When the aorta becomes enlarged, what we generally worry about is the aorta dissecting – the risk of it tearing or rupturing increases, and that is a really big, often catastrophic event,” said Phelan, a cardiologist at the Cleveland Clinic.

But what remains unclear is whether this same risk specifically applies to NFL players, who were on average slightly larger in physical size than the control group participants but generally more healthy. Most of the former athletes didn’t smoke, and they lacked the high cholesterol and high blood pressure generally considered factors among people with enlarged aortas.

The study, which involved 206 former NFL players screened between January 2014 to January 2015, is the first of its kind examining the aortic size of older professional athletes. The average age of the former players was 57. Among the control group, it was 54.

Previous studies have been conducted on younger elite athletes competing at the high school and college level. Those findings report a slight, but not significantly enlarged aorta compared to sedentary control groups.

The authors of the new study “are to be congratulated for providing a valuable data set that advances our understanding of vascular phenotype among aging former athletes,” wrote Aaron Baggish, M.D., in an editorial accompanying the study.

But, he said in a separate interview: “This study raises more questions than it answers, for sure.”

For example, the study doesn’t address whether the enlarged aortas are actually caused by playing professional football.

“Certainly, there are some plausible reasons why that might be the case but, at the same time, it may have as much to do with what happens to these men after they stop playing football, so we just don’t know,” said Baggish, director of Massachusetts General Hospital’s Cardiovascular Performance Program.

A more critical question that remains unanswered has to do with health perils for the older players.

“Does having a big aorta as a former athlete carry the same level of risk that it might in a sedentary person with high blood pressure? We really don’t understand what the risks associated with any of the findings are,” he said.

The best example for comparison would be heart size, Baggish said.

“Big hearts in normal people are typically a marker of heart disease, whereas big hearts in athletes are typically a marker of athletic physiology and good adaptation,” he said, referring to a condition often called “athlete’s heart” in which regular, intense levels of exercise lead to enlarged heart muscles and lower-than-average resting heart rates.

“So big is not necessarily bad when it comes to cardiovascular structures. We just really don’t know how the aortic story is going to play out yet.”

But Baggish described the new study on NFL players as “powerful” because it’s a reminder that more research is needed on the impact of football and other sports on the body.

“There’s all this concern about concussions and head injuries, but it turns out former football players are probably as likely, if not more likely, to have heart problems as they are to have head problems, so we need to be thinking of other ways to study these things,” he said.

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