Atherosclerosis Features Differ Among Male Athletes From Different Sports

Athletes, paradoxically, have been shown to have more coronary atherosclerosis compared with their less-active peers—now new data hint that the amount of plaque, and its makeup, may vary by sport.

In a study of asymptomatic men 45 and older free from overt CVD who participated in sports either competitively or recreationally, cyclists had a significantly lower prevalence of atherosclerotic plaques compared with runners (adjusted OR 0.41; 95% CI 0.19-0.87), with a nonsignificant trend toward a lower prevalence of coronary artery calcification (CAC), according to researchers led by Vincent Aengevaeren, MD (Radboud University Medical Center, Nijmegen, the Netherlands).

Moreover, among the men with plaques, cyclists were more likely than runners to have only calcified plaques (adjusted OR 3.59; 95% CI 1.14-11.31), which are associated with a lower risk of cardiovascular events compared with other types.

“These observations provide novel insights into the presence and type of coronary atherosclerosis among middle-aged male athletes,” the investigators write in their research letter published online February 13, 2019, ahead of print in JACC: Cardiovascular Imaging.

It’s too soon, however, to draw definitive conclusions about whether one sport may be better than another in terms of atherosclerotic risk, despite the “quite substantial differences between groups,” Aengevaeren told TCTMD.

“Should we advise people to perform more cycling than other sports? That’s not something we can say based on these analyses because it’s difficult to say how this works longitudinally,” he said. “It’s only a cross-sectional study, so you can’t really say anything about cause and effect and, if runners would switch to cycling, whether their coronary atherosclerosis would improve.”

Recent studies have demonstrated that athletes have increases in coronary atherosclerosis. An analysis of masters athletes, for instance, showed that men had more plaques—and more calcified plaques—than those who were less active. And a prior analysis by Aengevaeren’s group—from the Measuring Athlete’s Risk of Cardiovascular Events (MARC) study—showed that CAC and plaque prevalence increased along with lifelong exercise volume.

“Although such findings suggest that athletes performing high-intensity, high-volume exercise are at greater risk for cardiovascular events, these athletes frequently reveal calcified plaques, suggesting they are stable and at low risk of rupture,” the authors say. “The mechanism responsible for this atherosclerotic process in athletes is unknown.”

They point out that the risks and benefits of physical activity might differ by sport, citing a recent cohort study showing that mortality risks varied among people who cycled, swam, ran, or did aerobics.

To explore whether differences in coronary atherosclerosis could help explain those findings, Aengevaeren and colleagues performed a post hoc analysis of the MARC study, which included 284 middle-aged male athletes. All participants had a noncontrast CT scan for CAC scoring and underwent coronary CT angiography for plaque assessment.

The men were divided by type of activity: 25% were runners, 29% were cyclists, and the rest participated in other sports, most commonly soccer, hockey, water polo, and tennis.

Compared with runners, cyclists had a higher lifelong exercise volume, a lower prevalence of atherosclerotic plaques, and a higher prevalence of only calcified plaques (as opposed to noncalcified or mixed plaques). Plaque prevalence and morphology were similar in runners and “other” athletes, but “other” athletes were more likely to have plaque compared with cyclists.

The authors say the reason for the observed differences is unclear but speculate that it could have something to do with the nature of the activity.

“A key difference between cyclists and athletes performing other sports is that cycling is non-weight-bearing,” they explain. “Bone mineral density is sport specific, with increased or equivalent bone mineral density in runners but low bone mineral density in cyclists. Cycling may exert different effects on markers of bone turnover such as parathyroid hormone due to differences in weight-bearing, training duration, and/or intensity compared with running, leading to reduced bone mineral density and potentially an attenuated development of coronary atherosclerosis.”

But it could also be that the lower intensity of cycling “may induce less mechanical stress and blood pressure elevations in the coronary system,” they say.

Aengevaeren said that his group is planning on performing longitudinal follow-up of this cohort—which will include repeat CT scans and analysis of biomarkers—to try to tease out some of the potential mechanisms.

Commenting for TCTMD, Matthew Martinez, MD (Lehigh Valley Health Network, Allentown, PA), called the findings provocative but indicated that there is still a lot to learn about the interaction between exercise and cardiovascular risk, such as the optimal duration of activity and the type of exercise that would have the most benefit.

He said there is still some question, too, about whether people who participate in sports in middle age are directly increasing their coronary calcification—as some evidence suggests—or whether atherosclerosis caused by previous risk factors unrelated to exercise is simply being discovered at that age.

“I’m still not convinced that being an athlete increases your risk for coronary artery disease or, specifically, coronary calcification,” said Martinez, chair of the American College of Cardiology’s sports and exercise section.

The larger message should be that cardiovascular risk is reduced with exercise, Martinez said. But, like Aengevaeren, he said it would be premature to advocate for one type of activity over another. “I don’t think that this is enough for me to say that one type of exercise has a greater benefit than others.”