Give Athletes Some Slack: What Carotid IMT Data Tells Us

When assessing Carotid Intima-Media Thickness (IMT) in athletes, it’s essential to provide context to the numbers. IMT is a measure of the thickness of the inner layers of the carotid artery, and while it can indicate cardiovascular health, it doesn't always tell the full story—especially in highly active individuals.

Is the IMT Looking Healthy?

A healthy carotid IMT shows unbroken, intact arterial layers with no fatty streaks or deposits. For most individuals, a thin and smooth IMT is a positive indicator of heart health. However, for athletes, a slightly thicker IMT may not be cause for concern, as long as the arterial walls remain unbroken and smooth.

Stay Out of the Red Zone (Graph Reference)

The IMT graph used in these reports is derived from the ARIC study, which followed 10,000 people over 10 years to develop "normal" values based on the American population in the 1990s. It's important to note that this study did not distinguish between athletes and non-athletes.

Setting Expectations for Carotid IMT

It’s essential to manage expectations when reviewing IMT data.

For instance:

• Vascular surgeons consider intervention (endarterectomy) only at 70% occlusion.

• Hospitals typically report plaques starting at 30-39% blockage as "mild."

• Previously, anything under 0.6mm was considered ‘good’ in IMT reports, but now, anything under 0.8mm is acceptable as long as the arterial lining remains intact.

What About Athletes?

Athletes often show a thicker IMT due to their higher levels of physical activity. However, this does not automatically signal risk, as long as the arterial lining is smooth and free from fatty streaks.

The Caves-Cafe Study: A Key Source for Mortality Data

One of the most influential studies on Carotid IMT was the Caves-Cafe study, which tracked over 10,000 people for 10 years. This study provided critical data that allows us to categorize patients based on their plaque levels and IMT thickness.

A Dynamic Artery: The IMT “Walk” Effect

The IMT is dynamic. It exchanges nitric oxide with the blood and signals dilation during exercise, changing 7-13% throughout the cardiac cycle. This "walk" effect makes the IMT more flexible in children and athletes, something we aim to measure in future reports at Vasolabs.

My Experience: Carotid IMT, Athletes, and Risk

Through extensive research and personal intuition, I’ve found that when the IMT surpasses 0.8mm, the risks for heart issues begin to rise. In high-risk cases, studies have shown that the IMT layers can become visibly broken or lumpy, underscoring the need for caution.

To illustrate this point, I’ll share a personal experience: my son, a college rugby player, has an IMT near 0.6mm. Despite his athleticism and rigorous workouts, his arterial lining remains unbroken, indicating good heart health.

Conclusion: The Significance of IMT for Athletes

The take-home message is this: for athletes, a thicker IMT may be a natural physiological response to regular physical activity. As long as the arterial walls remain smooth and intact, this thickness is not a red flag. However, consistent monitoring through tools like the Carotid IMT scan is crucial to ensure heart health remains on track.

References:

• Golbidi, S., & Laher, I. (2016). Obesity and heart failure: A narrative review. Cardiovascular Diabetology, 15(1), 16. https://doi.org/10.1186/s12933-016-0336-2

• Kargl, J., & Müller, J. (2015). The role of inflammation in atherosclerosis and its implications for prevention and therapy. PMC4592756. https://pmc.ncbi.nlm.nih.gov/articles/PMC4592756/

• Eberhardt, R. T., & Waksman, R. (2001). Carotid artery disease: Diagnosis and treatment. PubMed Central, 11395035. https://pubmed.ncbi.nlm.nih.gov/11395035/