Physical Activity May Not Reduce Coronary Artery Calcification Risk

Exercise may not be the “cure all” for heart disease. Findings from a new study published by Mayo Clinic Proceedings suggest that highly-active men may not be reducing their risk of coronary artery calcification.

The authors discovered that highly-active Caucasian men are 86% more likely to have a build-up of plaque in their arteries at middle age compared with less active individuals.

Included in the study were 3175 patients aged 18 to 30 years who were participating in the CARDIA study. The authors examined the presence of coronary artery calcification (CAC), a measure of the accumulation of calcium and plaque in the arteries. The authors report that CAC is a warning sign of heart disease.

Patients self-reported physical activity during at least 3 examinations over a 25-year period. They were placed into 1 of the following groups: not meeting the national physical activity guidelines, meeting the guidelines, or exercising 3 times above the guidelines.

At year 25, CAC was measured by a computed tomography scan.

“We expected to see that higher levels of physical activity over time would be associated with lower levels of CAC,” said co-author Deepika Laddu, PhD.

However, the authors discovered that patients who exercised the most were 27% more likely to develop CAC compared with those who exercised the least.

When stratified by race and gender, white men who exercised at the highest level were 86% more likely to have CAC, while there was no increased risk of CAC among black participants who exercised at that level, according to the study. The authors report that a similar trend was observed for white women, but it was not statistically significant.

Previous studies have suggested a U-shaped trend between physical activity and disease risk, according to the authors.

“So, we performed this study to see if we can solve part of this puzzle,” said co-author Jamal Rana, MD.

The new study is especially valuable since it provides a look at long-term exercise patterns, according to the authors.

The investigators speculate that the link between CAC and exercise may be related to stress induced by physical activity.

“High levels of exercise over time may cause stress on the arteries leading to higher CAC, however this plaque buildup may well be of the more stable kind, and thus less likely to rupture and causes heart attack, which was not evaluated in this study,” Dr Rana said.

The authors plan to determine how the increased risk of CAC may affect the long-term health of patients, including how it influences the risk of heart attack and death, according to the study.

Although the findings suggest that white men who are very physically active may have an increased risk of CAC, the authors caution that individuals should not stop exercising, the study concluded.

“Because the study results show a significantly different level of risk between black and white participants based on long-term exercise trajectories, the data provides rationale for further investigation, especially by race, into the other biological mechanisms for CAC risk in people with very high levels of physical activity,” Dr Laddu said.