Coronary calcium score: what it means and how to interpret your results (AMA #5)

and a lot of questions come in or came in on coronary artery calcium or a CAC and so just this is a general question what is the deal with CAC some people say it's a marker other people say something else so take it away so coronary I'll see a coronary calcium score is a CT scan that's done dry meaning without any contrast so you lay on the CT table and it's a very quick scan and because there's no contrast anytime you see something that's really really bright white in there which is normally what color contrast

would be you know it's calcium so there's a scoring system where you can actually get some anatomic detail not to the degree of understanding how much narrowing there is of the arterial lumen but you can see which arteries so the left main artery the circumflex artery the left anterior descending the right artery the posterior descending artery and the amount of calcification is then scored and ranked against a percentile so you know this is one of those things that is certainly helpful and you know if there's one branch of statistics that medicine sort of innately teaches

you it's it's Bayes theorem where you update your probability based on new information my problem is not with the calcium score its width of a school of thought that says well a calcium score if it's zero means nothing matters you know you're sort of scot-free and that's you know unfortunately that's just categorically untrue and the data bear that out so a negative calcium score meaning a calcium score of zero absolutely means actuarially at the population level a lower risk of a coronary event and when we say coronary event we're the term ace is what we

use to describe it may a major adverse coronary event or cardiac event so heart attack stroke or cardiac death but it's not zero furthermore and this is where it gets a little complicated nearly 50 percent of fatal m' eyes occur in non calcified areas of coronary arteries now those data are also a bit misleading because many of those patients still had calcifications elsewhere so the way I think of calcification is it tells you how many times you've been broken into and what kind of repair you've done I mean that's a gross approximation so a biomarker

tells you how bad a neighborhood you live in so if you do a blood test on somebody and they're you know LP little a is high or their LDL P is high and they have lots of inflammation all these other things that says you live in a bad neighborhood it's dangerous there's there's a chance there's gonna be a break-in when you see a calcium score that's anything other than zero well that tells you you've already had an advanced lesion and that lesion had to be repaired because when you and I won't go through stories seven

levels of atherosclerosis because it's it's it's really complicated and it's hard to do without pictures we should we had a white board last yeah so that's right we can't run in the show notes which is the the sort of different types of lesions of atherosclerosis but calcification is an incredibly late stage repair so when you have calcification in a coronary artery I mean you've had real damage and it's been repaired and that becomes a marker of risk that basically suggests you need to be more aggressive in taking care of this this case but when it

is zero doesn't change the fact that you live in a bad neighborhood and it doesn't change the fact that you can have lots of arterial damage that just hasn't shown up at the stage of calcification so you can have plenty of soft plaque that's still there without calcification that's still an enormous marker of risk and that doesn't get picked up with no so you know what we what we typically do with patients is and it depends every case is different and so you know there are some times when I just do a calcium score on

a patient and if it's zero I don't do anything further there are other times when even if it is zero I still reflux into a coronary angiogram so a CT angiogram which does pull much more anatomic detail including the presence of soft plaque but even there you know you can you still can't really see you know plaque that is vulnerable but if a patient has a coronary calcium score that is zero and their CT angiogram looks impeccable you know look there that's that's a much better sign than anything not being in that case and of

course it begs the question well would you still treat a patient in that situation that's a hard question but it also depends on your time frame and so the younger a patient is with that finding the less confident you are that they are one of the lucky people that seems largely immune from coronary disease where I find these tests most helpful is actually not in young people but in older people it's and I've and I you know I've got a patient right now but I actually just sent to get this scan she'll probably have in

the next two weeks you know very very wonky lipid numbers very you know complicated apoE status but metabolically just fit as a fiddle I mean she's just incredibly healthy but her lipid numbers couldn't suck more and you know I'm sort of trying to decide how aggressive do we want to be in lipid management she is old enough which is not to say she's particularly old I don't even think she's 60 yet she is old enough that if she has a perfect CT angiogram and her calcium score is zero which it by definition is if she

has a perfect CT angiogram I would you know that would be enough period of exposure you know call it 60 years that I would say you know there's something going on in this woman where you know other factors that are equally important to the lipoprotein the endothelial function the immune response are working enough in her favor that you know she might not need to be managed very aggressively despite the fact that she's there so in other words she might live in a really bad neighborhood but she just happens to have a pitbull that's in her

front yard that's kind of keeping a bad guys away mm-hmm so I was just thinking about we talk about atherosclerosis and you have coronary artery calcification and just from like a naive point of view atherosclerosis is hardening of the arteries if you have a if you have a positive tack and I mean we can go through some of the ranges of yeah my score is 25 or my score is 2500 euros that oh yeah I've seen I've seen higher is there a number that if it's nonzero does that mean that you have some form of

technically atherosclerosis or is it not that black and white it's not atherosclerosis is is can be present even without a single shred of calcium and and to your question about the number it really is a function of your age as well and gender so the number is not nearly as important to me as the percentile it's where do you stack up against your peers so for example a calcium score of 6 if you are 35 to 40 years old would put you at the 75th to 90th percentile that even though that is a tiny tiny

tiny burden of calcium that's a significant problem a calcium score of 6 if you were 80 years old means you have no calcium even a calcium score of 6 to 10 if you're 60 years old would be considered quite low so yeah it has to be taken in the in the context of age have you looked into I know it's what is it Arthur a g'sten it's the a g'sten score yeah and there's some things that they look at I think it a couple of things they look at they look at the volume and the

density that's right double-click on that stuff and if that would that further stratify III mean I I don't use that to further stratify but where I think it is going to become more and more interesting is there are more and more data emerging that say that not just the burden of calcium but the density of calcium while on therapy may be more predictive so I don't know if this literature has been published but I've seen it in abstract form where on statin therapy well so here's what we already know we already know that in general

when a patient has a calcium score of something that's not zero you put them on a statin and over time their calcium score expands even though that sounds like a negative thing it turns out to be a good thing provided they've been on a statin so that seems to be a plaque stabilization I've seen data again I don't think I've seen this info published form but certainly an abstract form that says as the density of plaque or the density I'm sorry of calcium increases on statin therapy that also it portends a better outcome or a

greater stabilization now very recently data came out on pcsk9 inhibitors that said the opposite so patients on pcsk9 inhibitors which by definition in the studies for EI and odyssey were also on statins actually saw a reduction in plaque volume or calcification and we know that they had positive findings so you know truthfully that just tells me there's a lot we don't know yet and I think it's I find it difficult to use and not necessarily helpful to use cereal calcium scores prognostically although you know I'll stand corrected by a patient of mine who had a

calcium score of you know 10 when he was you know 20 years ago so you know before he's my patient but if you look at if you please had a number of calcium scores over the past 20 years and they've gone from 10 to you know 40 to 170 to 650 to 1500 to 4,000 so and this is actually a very interesting case because this is a patient whose lipid levels are not horrible he's not a guy cuz he's obviously been medicated for a large part of this period of time he does not have an

elevated LP little a but his family history is really significant for cardiovascular disease his father had his first mi in his 40s this is a patient in fact who I said to him I said if I would have bet stupid sums of money have I without seeing your labs that you had an elevated LP little a because for all for all intensive purposes he looks like someone who would have an elevated LP little 8 and he doesn't which again speaks to just the complexity of the disease and there are undoubtedly other genetic factors because clearly

this is genetic that we haven't yet they know elucidated so and weird when you're talking about the percentiles I think I've seen like Mesa the multi-ethnic study of atherosclerosis says they have a calculator I think as well that you can you can look at your risk and you can just like you're talking about that you could have a score of five and that would denote high risk depending on what you plug in for your age what your age actually is compared to somebody older right and you can also you know use other risk factors do

you smoke do you have high blood pressure again atherosclerosis you know there are sort of four things that are out of whack when you're getting atherosclerosis and there are therefore obviously an you know an infinite number of combinations given how multivariate each of those things are but you know sort of if metabolism is out of whack if lipoproteins are out of whack if inflammation is out of whack if the endothelium is not functioning well all of those things are gonna predispose you in staunton think that's sort of fascinating too that you could have more stable

plaque which also I think suggest too that when we talk about calcium we might say Oh calcium is bad it's not it's it's probably a bad sign but the calcification is the it's sort of the repair that's absolutely correct the calcium per se is not the problem it is it is that it tells you something bad has happened and that's such that's so important for people to understand it's you know if anything that calcium is probably doing more benefit than harm yeah it's the fact that you have it that's upsetting yeah upsetting you know and

so it's actually it's looking and it's not a biomarker it's actually looking at damage but in a sense it's telling you that the damage has already been done which may be a predictor of future risk correct and that's one of my big pet peeves is when people talk about a calcium score like they talk about a biomarker it is not a biomarker it is a backwards looking piece of evidence that you have disease and that damage has already occurred to the artery mmm yeah I think you mentioned that like you're talking about with break-ins or

something like that yeah the break-ins already had in you happened yeah yeah which might yeah okay now if we want to cover this too but I remember seeing a paper recently actually we went back and forth a little bit on it with um was it the Cooper clinic and we call it as a Colorado thought it was in Dallas but okay us yeah are you right where they looked at people what do they talk heavy extreme exercise yeah endurance exercise and they looked at CAC they didn't do a follow-up but they looked at their baseline

CAC and then they looked at how much exercise they did and they stratified and one of the things that one of the people that I think either was involved in the study or done work on us he called it hearts of stone I think I don't think to that effect where if this was in JAMA a few months ago yeah and they they showed that they stratified for every what the CAC score was maybe lower than 100 compared to CAC scores greater than 100 and then they stratified into three buckets of below 100 and above

100 and the three buckets for each so there's six total the three for each was let's say low exercise but probably more a way more exercise than the average Joe you know medium exercise and then extreme exercise which is really like at the level of probably when you were training for your having a channel and things like that and what they found was part of what I think they found to eat almost irrespective of CAC is that in terms of exercise the people who exercise the most and this is epidemiology prospective epidemiology take it with

a grain of salt but the if you compared the general risk of somebody for all cause mortality or cardiovascular death or things like that they seem to have much lower rates but what was interesting is some there's a small subset and it was relatively small when you actually looked at the the end of each of these buckets it was relatively low but there was a significant number of people or I should say a substantial number of people high exercisers but they were also older which might get to that 40 push-ups thing you might talk about

that so they were you know about almost ten years older on average which you know with you talked about the CAC progression you know that they're much more likely to have a higher score but they had a higher score when you compared though their rates especially just to the general population they still had much lower levels of all cause mortality and in cardiovascular death and probably although the mace you know components as well which yeah I mean I think in part this speaks to the ubiquity of mechanisms by which exercise is beneficial but at the

same time suggest that look there's going to be a subset of individuals and/or circumstances under which exercise can also be damaging to the heart now we know this at the level of you know James O'Keefe has done a lot of work on this at the level of the electrical system you know and the way I kind of explain this to patients is the you know the heart's a muscle whose electrical system exists within the wall so the more often it is stretched and held for long periods of time in said stretch position the more you

are damaging the electrical architecture of it and so that's why we see a significantly high incidence almost 10x out of the general population in highly highly highly trained athletes for dysrhythmia atrial fibrillation being a common example so that type of damage to the heart is pretty well understood visa via its relationship to exercise but the other thing that I think always has to be considered is look we don't know what kind of shear forces a person is under in at the again we go back to what I said earlier the endothelium is such an important

part of this that if you're damaging the endothelium all other things being equal you can still increase the risk of damage to the heart so yeah it's tough and I would hate for the message from that study to be well you're better off not exercising and I and I mean right that that's always the risk you run when when these sort of studies they're you know complicated to read in the journals wind up in newspapers where the person writing about it only has you know 800 words to write something and and also has to include

a headline-grabbing you know we're an attention-grabbing headline and so you know definitely the takeaway is not that you know you shouldn't exercise but it's that you know there's more nuance to this yeah I would say if I was an extreme exerciser and you have that cack under 100 and the kak over 100 all things being equal I'd like to be in the under 100 group but when you looked at the over 100 group and you compared them just about to any other you would say I would love to have that type of at least associate

wrists yeah you know even with the with the scores like that yep yeah I think you just like saying kak I think there's at least a chance that that's part idea you see