NIJMEGEN, THE NETHERLANDS — Men with higher levels of lifelong physical exercise have significantly more coronary artery calcification (CAC) compared with those with lower exercise levels throughout life, but their coronary plaques tend to be lower risk—that is, mostly calcified or mixed calcified/noncalcified, suggests a new study[1].
The analysis, published online in Circulation on April 27, 2017, of almost 300 middle-aged male athletes showed that endurance athletes with the highest levels of physical exercise had a 47% increased risk of developing CAC and a 56% increased prevalence of plaque. But they were 3.5 times more likely to have plaques with the lower-risk composition.
"These observations may explain the increased longevity typical of endurance athletes despite the presence of more coronary atherosclerotic plaque in the most active participants," write the authors, led by Dr Vincent Aengevaeren (Radboud University Medical Center, Nijmegen, the Netherlands).
"Exercise training increases coronary blood flow by increasing arteriolar diameters and/or density and improves vasomotor reactivity of the coronary resistance arteries," they write. "Therefore, beneficial vascular adaptations such as an improved coronary flow reserve may also allow athletes to better deal with coronary stenoses and experience fewer symptoms and events than the general population with a similar plaque burden."
Aengevaeren observed for heartwire from Medscape that, in the most active athletes, "the plaque types are of a more benign composition, at least compared with studies in the general population."
Nevertheless, Aengevaeren said, for athletes with "substantial coronary atherosclerosis, we think it would be best to prescribe them statins," as it is known that the drugs significantly reduce cardiovascular risk.
He does not believe, however, that there is a case for screening athletes for the presence of atherosclerosis, as the clinical relevance of the increased prevalence of coronary artery calcification is currently not clear.
Asymptomatic, Athletic Men at Least 45 Years Old
The current analysis, from the Measuring Athlete's Risk of Cardiovascular Events study, included men aged at least 45 years old who were asymptomatic, engaged in competitive or recreational leisure sports, and were free of known cardiovascular disease.
Based on self-reports of lifelong exercise history, the participants were divided into lifelong exercise volume groups of <1000, 1000 to 2000, and >2000 metabolic equivalents of task (MET)-min/wk. In addition, the exercise they performed was classified as light (<3 MET), moderate (3–6 MET), vigorous (6–9 MET), or very vigorous (≥9 MET).
Low-dose cardiac computed-tomography scanning was used to determine the degree of CAC and the plaque characteristics, which were classified as calcified, noncalcified, and mixed.
A total of 284 of 318 participants from the original study were eligible for inclusion. The mean age of the men was 55.0 years, and the average lifetime exercise volume was 2.9 hours per week, at a mean of 1356 MET-min/week.
The team found that 150 (53%) of the participants had coronary calcification, their mean CAC score reaching 35.8. Athletes with CAC were older and more likely to have risk factors traditionally associated with cardiovascular disease.
In multivariate analysis accounting for age, body-mass index, systolic blood pressure, smoking history, antihypertensive drug therapy, total cholesterol, family history of coronary heart disease, use of statins, and diabetes, lifetime exercise volume was significantly associated with both CAC and plaque formation.
Compared with the least active athletes, those with an exercise volume >2000 MET-min/week had significantly higher CAC scores, at 9.4 (95% CI 0.0–60.9) vs 0 (95% CI 0.0–43.5, P=0.019).
They also had a significantly greater prevalence of CAC, at 68% vs 43% (odds ratio [OR] 3.20, 95% CI 1.56–6.57; P=0.001), and plaque, at 77% vs 56% (OR 3.35, 95% CI 1.57–7.14; P=0.002).
Furthermore, very vigorous-intensity exercise was significantly associated with the formation of CAC, at an OR of 1.47 (95% CI 1.14–1.91, P=0.03), and plaque, at an OR of 1.56 (95% CI 1.17–2.08, P=0.002).
Among athletes with CAC, the researchers found no differences across exercise-volume groups in terms of CAC score, area, density, and regions of interest.
However, compared with the least active athletes, those with an exercise volume >2000 MET-min/week had a lower prevalence of mixed plaques, at 48% vs 69% (OR 0.35, 95% CI 0.15–0.85; P=0.017) and were more likely to have only calcified plaques, at 38% vs 16% (OR 3.57, 95% CI 1.28–9.97; P=0.002).
"Nails Down the Concept"
Dr Douglas P Zipes (Indiana University School of Medicine, Indianapolis), not connected with the study, said in an interview that it was "very well done, and pretty well nails down the concept."
What the analysis does not show, however, is "why it happens, and I don't think we're entirely clear as to the mechanisms." He pointed out that endurance athletes show heart damage during races, which suggests "wear and tear on the heart."
He added: "I think one of the important observations here was that the plaque composition is different in the endurance athletes compared with the controls, which suggests a different mechanism producing the atherosclerosis, and the fact that more of their plaques were calcified, indicating that they would tend to be more stable."
Zipes also agreed that screening athletes for atherosclerosis is "a very volatile topic" and would be problematic. "We've discussed screening countless times in various organizations, and the general consensus is that screening youngsters prior to athletic participation is fraught with difficulty.
"It can be expensive, there can be both false positives and false negatives and, if we're screening for sudden death, which is usually the main impetus, in the United States there are less than 100 sudden deaths among young athletes annually. So, we're talking about very small numbers for a very expensive procedure such as screening."
Zipes said, however, that screening endurance athletes into their career "certainly could be done" and, notwithstanding the "reassurance that endurance athletes tend to live longer, despite the atherosclerosis, it would still be reasonable to treat them with statins."
The research was supported by a grant from Sportcor, a Dutch national registry of sudden cardiac arrest in athletes, the Foundations Wetenschappelijk Onderzoek Hart-en Vaatziekten and Bijstand Meander Medical Center Amersfoort, the Rontgen Foundation Utrecht, and Philips Healthcare. Dr Aengevaeren reports no relevant financial relationships. Disclosures for the coauthors are listed in the paper.
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Heartwire from Medscape © 2017
Cite this: Coronary Plaques Common but 'Benign' in Lifelong Athletes - Medscape - May 12, 2017.
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