Enlarged Aortas Are Widespread in Former NFL Players, Study Shows
No prior studies have explored aortic dimensions in former elite athletes after they reach middle age. The new findings are striking, but what might they mean clinically?
Middle-aged former National Football League (NFL) players are twice as likely as controls from the general population to have an enlarged ascending aorta, independent of age, body size, race and risk factors for aortic dilation. So finds a new cross-sectional cohort study led by Cleveland Clinic researchers and published Nov. 9 in Circulation: Cardiovascular Imaging. The investigation also showed that mean ascending aortic diameter was approximately 12 percent greater in the retired athletes overall than in a well-matched control group.
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“Even after adjustment for risk factors, former NFL athletes had a twofold higher prevalence of aortic dilation, defined as an aorta dimension greater than 40 mm,” says principal investigator Dermot Phelan, MD, PhD, Director of Cleveland Clinic’s Sports Cardiology Center. “The players’ aortic enlargement was observed despite their having a lower risk profile. We need to better understand what happens to these athletes’ bodies long-term.”
He adds that while no prior findings suggest that elite athletes are at higher risk of developing a life-threatening aortic dissection later in life, these results call for “caution and regular monitoring of these individuals until further studies are done to explore what these findings mean clinically.”
Prior studies indicate that ascending aortic dimensions in elite athletes are larger than in the general public but still fall within established limits for the general population, with less than 2 percent of athletes exceeding the guideline-based 40 mm threshold for aortic enlargement. But these studies have been small and limited to young, currently active athletes.
The new Cleveland Clinic study is the first to explore aortic dimensions in older, former elite athletes and compare them with dimensions in a well-matched control group.
The researchers used gated noncontrast CT to measure dimensions of the midlevel ascending aorta in a cohort of 206 middle-aged former NFL players participating in a voluntary cardiovascular screening program run by Cleveland Clinic. They compared findings with CT studies from an age- and body size-matched control group of 759 men from the Dallas Heart Study, a population-based cohort study with an ethnic distribution similar to the retired NFL players.
The former NFL players were slightly older than the controls (median age of 57.1 vs. 53.6 years) and slightly larger in terms of body surface area (2.4 vs. 2.1 m2) and body mass index (32.4 vs. 30.0 kg/m2). The retired players had a more favorable profile of traditional cardiovascular risk factors, including lower rates of hypertension and current smoking and better lipid levels.
Despite this superior risk profile, the NFL retirees had a significantly larger midascending aortic diameter than the control group, 38 ± 5 mm vs. 34 ± 4 mm (P < .0001). This difference persisted after multivariate adjustment for age, body surface area, race and a host of cardiovascular risk factors known to influence aortic size (P < .0001).
Notably, the prevalence of aortic dilation (> 40 mm) was 29.6 percent among the NFL retirees compared with 8.6 percent in the control group (P < .0001). After multivariate adjustment, the retired players were still twice as likely to have a diameter greater than 40 mm (P = .014).
This is striking, Dr. Phelan notes, since prior published data reveal this degree of aortic enlargement in less than 2 percent of active elite athletes. What’s more, a full 9 percent of NFL retirees in the current study had marked aortic dilation of ≥ 45 mm.
Dr. Phelan cautions, however, that these data must be considered hypothesis-generating. “The clinical significance of our findings is unknown and will require further study,” he says, especially in light of the sample size and the potential for selection bias given the voluntary nature of the screening program for NFL retirees.
He speculates that his study’s findings likely reflect adaptation of the aorta to the hemodynamic stress of repetitive strenuous exercise over many years. “This is an important area of research, as recommendations on the timing of medical therapy initiation, activity restrictions and even surgical indications could potentially be influenced in an effort to reduce the risk of aortic dissection or rupture,” Dr. Phelan says. “For now, when evaluating a patient with an enlarged aorta, a history of extensive sports activity should be noted and perhaps prompt extra vigilance in monitoring.”
In an accompanying editorial in Circulation: Cardiovascular Imaging, two cardiologists from Massachusetts General Hospital write that “the authors are to be congratulated for providing a valuable data set that advances our understanding of vascular phenotype among aging former elite athletes.” They call attention to the stark contrast in prevalence of aortic dilation between this Cleveland Clinic study in middle-aged NFL retirees and a recent study among young prospective NFL players that found an aortic diameter greater than 40 mm in only 1 of 983 athletes (0.1 percent). The reasons behind this “striking difference” in prevalence of aortic dilation between differing age cohorts of elite athletes “represent keys areas of future work,” the editorialists write.