Would You Benefit From A Coronary Artery Calcium Scan?

Betteridge’s Law of Headlines states that any headline that poses a yes/no question can be answered with “no”.

This is a very good general rule of thumb, and it works because most of the time, if the answer were “yes”, then the headline would have stated it as a declaratory statement, so questions are often used when the publication wants to make it seem like a reasonable possibility, but wants to stop short of being liable for claiming it as true.

However, in this case, it really was a question, to which which the answer is “probably not, but it depends on your condition”.

So, whom would it benefit?

CAC by name…

The coronary artery calcium (CAC) scan detects calcium-containing plaque in the coronary arteries, with higher CAC scores generally indicating more calcified plaque and greater cardiovascular risk.

So, naturally it’s been a popularly-used diagnostic tool.

But it might not be that useful…

Researchers (Lucia Petito et al.) followed (in the longitudinal study way, not in the stalker way) 6,098 adults aged 45 to 79 without known cardiovascular disease at the start. Their mean average age at start was 61.4 years, 52% were female, and 49% had a CAC score above zero.

Over 10 years, 366 participants, which is 6%, experienced an atherosclerotic cardiovascular disease event, such as a heart attack or stroke.

There’s another diagnostic tool the PREVENT calculator, which estimates 10-year and 30-year cardiovascular risk using routinely available information such as age, blood pressure, cholesterol, and sex.

Adding CAC testing to PREVENT scores increased the accuracy from 0.73 to 0.75 (on a scale of 0.0 which means no accuracy, to 1.0 which means complete accuracy).

This accuracy increase of 0.02 on the scale is not that helpful to most people:

• Low-risk patients: routinely scanning people at low risk may provide little useful information while exposing them to radiation and potentially leading to additional testing and costs.
• High-risk patients: scanning people already at high risk may also add little to treatment decisions because they would generally already be recommended for statin* therapy regardless of their CAC score.

So, is it useful to anyone? Yes, among people in the borderline-risk category, 10-year cardiovascular events occurred in:

• 1.9% of those with a CAC score of 0
• 3.9% with CAC greater than 0 but less than 100
• 7.4% with CAC of 100 to less than 300
• 14.3% with CAC of 300 or greater

So, for those in the borderline risk band, the results can actually say something useful!

You can find the paper itself, here: Predictive Utility of Coronary Artery Calcium Score Added to the PREVENT Atherosclerotic Cardiovascular Disease Equations

*That these would be recommended for statin therapy is particularly interesting, on account of Why Statins Cause Muscle Pain ← it has to do with triggering calcium leaks!

There are of course also often other issues with statins, which you can read about in detail, here: Statins: His & Hers?

Or if you want to get really into detail, then check out this excellent book that we reviewed (and whose information largely informed the above-linked article): The Truth About Statins – by Dr. Barbara H. Roberts

Want to learn more?

For a much deeper dive into the more general topic than we have room for here, you might want to consider this book we reviewed:

Prevent & Reverse Heart Disease – by Dr. Caldwell Esselstyn

Take care!