I'm a Vascular Surgeon — Stop Getting Repeat CAC Scans. Here's Why

If you’ve had a positive calcium score (CAC score), you’ve probably asked the obvious next question: when should I repeat it?

In this video, I explain why I generally do not order another calcium score if the first one is positive—and what I prefer to use instead to follow atherosclerosis over time.

We walk through what a coronary artery calcium score actually measures, why it’s really just the tip of the iceberg, and why a higher repeat score does not necessarily mean your treatment failed. I also explain the difference between calcified plaque and soft, lipid-rich plaque, why that distinction matters for heart attack and stroke risk, and why serial CAC testing often adds less useful information than people think.

I also cover:
 • why calcium scores can be helpful as a one-time risk assessment tool
 • why I’m more cautious about relying on CAC in younger patients
 • when I will repeat a calcium score
 • why I prefer more informative tools like CCTA and CIMT for tracking disease over time

If you’re trying to understand calcium score progression, plaque stabilization, soft plaque, coronary artery disease, heart disease prevention, stroke prevention, ApoB, Lp(a), statins, and cardiovascular risk, this video is for you.

Let me know in the comments: If your first calcium score was positive, would you want to repeat it—or would you rather use a different test to follow your risk?

#CalciumScore #CACScore #HeartDiseasePrevention #Atherosclerosis #CardiovascularHealth #CIMT #CCTA

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___________________________
🧬 About Dr. Lily Johnston
  
Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.
  
#MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

Transcript

SPEAKER_00 0:01

Let's talk about why I never order another calcium score if your first one was positive. Hey guys, I'm Dr. Lily Johnston. I am a board certified vascular surgeon. I also specialize in cardiometabolic prevention. So hopefully you will never need me as a surgeon. Now I have a prevention practice and I see lots of patients who come to me with a calcium score that's positive and they want to know when we should repeat it? Where are how are we going to follow this disease that I have? How are we going to know if my treatment is working? I was recently at the KOSI conference in Las Vegas, thanks to Dave Feldman for that. And we talked about why I don't order a second calcium score, but what alternatives we do have to help monitor the efficacy of our treatment when we're working on prevention. So let's talk about what a calcium score represents, why I don't think it's helpful to get a second one, and what we can do instead. So coronary calcium. Calcium is the dense part of the plaque that is old, that has been stabilized by the body over the years, and it represents both the calcified stable plaque, but also what's underneath. So I'm going to show you some slides here and we're going to go through what happens over time and what the different possibilities are. So think of this calcium like the tip of the iceberg. You have that, but there's also all of the soft, lipid-rich plaque underneath. And if you've watched my earlier video about the pros and cons of different kinds of cardiac imaging, you know that a calcium score, while being very accessible, does not show that soft, lipid-rich plaque that's underneath. And that soft lipid-rich plaque is what causes plaque rupture, heart attacks, strokes, and often limb loss. So that's really what we're looking to see. What's what, you know, if we're thinking about what's going on, the calcium score represents the totality of the plaque by imaging the just the top part of the iceberg. So think of it as a harbinger of what's beneath the surface. Here's the problem. About 10% of people who have a zero calcium score will still have soft, lipid-rich plaque. And that is why I don't always love calcium scores in younger patients or in folks who have a lot of other risk factors, but who might still be early in the disease process. But here's the other thing. Let's say that today your calcium score is 50, right? That's T equals zero times zero. And somebody says, well, tech is less than 100. That's not so bad. That's still very low risk. Let's just follow it and see what it looks like in a few years. So there are two options though. The first is that you just go on your merry way, you don't do anything about your risk factors, and then we get another calcium score in a few years. Now your calcium score is 150. Well, in the case where you've done really no changes to lifestyle, no changes to medications or supplements or exercise or anything else, this represents progression of disease. Now you have three icebergs and all of that soft, lipid-rich plaque underneath, because the just disease has continued to progress unimpeded over that time frame. And that is why, in general, in untreated populations, when we see an increase in calcium score, we see an increase in events. This does represent an increase in risk over time. And you say, okay, well, great, now my score is 150. Now we should treat me, but now we have incurred this additional risk from having all of this soft lipid-rich plaque that we now have to undo or try to stabilize all of this in addition to what was there five years ago. But here's the other situation. You got your first calcium score of 50, and you said, oh, wow, I have some plaque. That worries me. I'm going to be very proactive. I am going to get all of my risk factors under control, like my blood pressure, my substance use, my nutrition, my exercise. If I have risk factors like familial hypercholesterolemia, then perhaps I'm taking lipid-lowering medications or supplements that will lower my APOB levels. If I have elevated LP little A, I'm working on getting my APOB down as low as possible. All of these things in combination mean that we are treating or managing those risk factors. Now somebody says, okay, great, let's see if that's working. So we get another calcium score in five years. And instead, what we have is another calcium score of 150. But this is a different result, right? It's the same number. But what has happened is in fact we've lowered the water line. So it's the same iceberg. But what we've done is taken a bunch of that unstable lipid-rich plaque and converted it into the stable calcium-rich plaque that doesn't really cause trouble for people. And people think of this as the statin paradox, which is to say patients who are on statin therapy have an elevated calcium score, but overall it decreased risk of mortality and events when we're talking, especially in this secondary prevention population. So what you've done is taken the stable or excuse me, the unstable plaque and made it stable. This is a good thing, but it means we can't really use this calcium score to help us understand the effect of treatment. The other point I really want to drive home here is that calcium scores are not a very precise test. We think that the average variability of a test from one minute to the next is like 15 to 40 percent. So that means if you take me and you put me on a scanner and I get a score of 100, you could put me on that same scanner five minutes later and maybe get a score of 115 or 120. And that is the variability that we can see just between the same person on the same table on the same day, 15% at least. So that's not very precise, which is to say, if you now get another score in five years and it's again 50 to 150, well, how much of that is variation in the test, variation in the scanner, and the imprecision of coronary calcium? Better tools are things like CCTA, coronary angiography, where we can really quantitate the percent of plaque that is densely calcified versus the percent that is soft and vulnerable, or we can use CIMT, my own tool of choice, as you know, and look at that insal medial thickness, which is precise down to hundredths of a millimeter. So we have a lot of good precision with that test as well. So for all of these reasons, I think coronary calcium scoring is a really reasonable choice to understand at a given point in time whether you have the presence of plaque, whether we should consider managing risk factors in treatment. I know that's a controversial point, but I do think it really helps a lot of people understand the true reality of their risk factors in their own body. Um, and all of those things make calcium score a very reasonable choice for a one-time test. The times I will repeat a calcium score is if your original score is zero, and we want to make sure that we don't have any, you know, you're not in that 10% of people who has soft plaque underneath uh all of that that we can't see and that might show up later. So I think when people talk about the power of zero, I take that with a grain of salt. And I like to see a second score of zero. And if I see two scores of zero five to ten years apart, um, for me, that's a pretty good warranty for the next five to 10 years. Now, if you have that in your in your 70s or 80s, I feel really good about that. If you're in your 40s and 50s, we'd talk about again serial imaging over time and how we can use that to manage your risk. But uh I will get another calcium score if the first one is zero, because I think double zeros are really powerful in terms of helping understand how your risk factors are behaving in your body and provide a really great reassurance that we are not showing progression of soft plaque over time. A very reasonable question you might have is but doc, doesn't it tell us something about my risk if we show progression or if the rate of change is very high? What do the studies tell us about using a second CAC score as a marker for better understanding of risk? And the truth is, another CAC score doesn't actually provide a huge amount of additional information when we look at everybody at the population level. We have actually done this study. We've looked to see whether the rate of change is a great predictor of risk above and beyond the score itself. And honestly, it's not that helpful, right? The score itself is really your best predictor of risk insofar as the score can tell us anything about you as a patient. It doesn't tell us what your risk factors are, it doesn't tell us what your trajectory is, but neither does the serial CAC. And that's really the point that I'm trying to make here is yes, getting a sense of rate of change over time for an IMT is helpful, right? That's a bigger picture issue that talks to us about the inflammation in the arteries, the soft plaque that's underneath everything else. And so does coronary angiography, where we can look at all the plaque that exists, but the calcium score by itself is just the tip of the iceberg, and it's really not telling us enough about what's going on underneath the hood to help you understand how to change whatever it is that you're doing to reduce your risk going forward. Let me know if you have comments about this. Hit me up in the comment section. If you like this video, please hit that like button, subscribe to the channel, and share it with somebody who needs to hear it. Until next time, take really good care.