Coronary Artery Calcium Score vs. Coronary CT Angiogram: What They Are and What They Show

What is a coronary artery calcium scan (CACS)?

A CACS is a simple CT of the heart performed without injection of any contrast dyes that permits the easy identification of calcification (plaque) in the three major heart arteries. There are no needles used, no pain, and no risk to your kidneys.

By good fortune, the density of arteries is different than the fat they sit in and the muscle and blood that are nearby in the heart. Calcium comprises about 20 percent of plaque in arteries but is such a different density than the rest of the heart that even small amounts show up like a beacon of aging and damage in by just holding your breath for 10 seconds.

What Should You Consider?

Whether you have ever had symptoms suspicious for heart disease or not, a CACS of zero buys you 98% peace of mind for a few years at least according to this study. This is far in excess of stress tests which may be 85% accurate, expose you to much more radiation, and cost 10–15 times more.

I generally recommend the basic CACS scan to patients with no history of coronary disease (no stent, bypass, heart attack, prior cardiac catheterization show plaque). If the score is abnormal, I generally do not recommend repeating the CACS in the future as there is no convincing data the CACS can be reduced (although soft plaque can be reduced) and the need for intensive therapy is clear. If a repeat CT is done in a patient with an abnormal CACS, I strongly recommend the CCTA, not the CACS, to get the extra information (percent narrowing and amount of soft plaque).

A new option is to use artificial intelligence (AI) to interpret the CCTA for the most precise measurements offered by Cleerly Health. We have a referral relationship with them and dozens of patients have had that advanced AI scan interpretation.

In those with a CACS of Zero, the best outcome, a repeat CACS is considered in 5-7 years to see if the score stayed zero (a good outcome) or has progressed to calcified coronary arteries. 

FYI, I have had a CACS of zero at age 40, 50 and 60. I will let you know at age 70 if I do another but that is a number of years away! 

Dr. Joel Kahn

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