The skeptical cardiologist has been utilizing coronary artery calcium (CAC) scans to help decide which patients are at high risk for heart attacks, and sudden cardiac death for the last decade. As I first described in 2014, (see here) those with higher than expected calcium scores warrant more aggressive treatment, and those with lower scores less aggressive treatment.
Although, as I have discussed previously, CAC is not the “mammography of the heart” it is incredibly helpful in sorting out personalized cardiovascular risk. We use standard risk factors like lipids, smoking, age, gender and diabetes to stratify individuals according to their 10-year risk of atherosclerotic cardiovascular disease (ASCVD) but many apparent low-risk individuals (often due to inherited familial risk) drop dead from ASCVD and many apparent high-risk individuals don’t need statin therapy.
Previously, major guidelines from organizations like the AHA and the ACC did not recommend CAC testing to guide decision-making in this area. Consequently, CMS and major insurers have not covered CAC testing. When my patients get a CAC scan they pay 125$ out of their pocket.. For the affluent and pro-active this is not an obstacle, however, those struggling financially often balk at the cost.
I was, therefore, very pleased to read that the newly updated AHA/ACC lipid guidelines (full PDF available here) emphasize the use of CAC for decision-making in intermediate-risk patients.
For those patients aged 40-75 without known ASCVD whose 10-year risk of stroke and heart attack is between 7.5% and 20% (intermediate, see here on using risk estimator) the guidelines recommend “consider measuring CAC”.
If the score is zero, for most consider no statin. If score >100 and/or >75th percentile, statin therapy should be started.
I don’t agree totally with this use of CAC but it is a step forward. For example, how I approach a patient with a CAC of 1-99 depends very much on what percentile the patient is at. A score of 10 in a 40-year-old indicates marked premature build-up of atherosclerotic plaque but in a 70-year-old man it indicates they are at much lower risk than predicted by standard risk factors. For the first individual we would likely recommend statin therapy and very aggressive lifestyle changes whereas for the second man we could discuss taking off statins.
Neil Stone, MD, one of the authors of the guidelines was quoted as saying that the imaging technique is “the best tiebreaker we have now” when the risk-benefit balance is uncertain.
“Most should get a statin, but there are people who say, ‘I’ve got to know more, I want to personalize this decision to the point of knowing whether I really, really need it.’ … There are a number of people who want to be certain about where they stand on the risk continuum and that’s how we want to use it,”
Indeed, I’ve written quite a bit about my approach to helping patients “get off the fence” on whether or not to take a statin drug.
N.B. There are two interesting sentences in the guidelines which I’ll need to discuss some other time
-When the CAC score is zero, some investigators favor remeasurement of CAC after 5 to 10 years
–CAC scans should be ordered by a clinician who is fully versed in the pros and cons of diagnostic radiology.
–In MESA (Multi-Ethnic Study of Atherosclerosis), CAC scanning delivered 0.74 to l.27 mSv of radiation, which is similar to the dose of a clinical mammogram
Here is the full text of the section
-18.104.22.168. Coronary Artery Calcium
2018 Cholesterol Clinical Practice Guidelines