Should I get a coronary calcium score?
Okay, so we can put a man on the moon. Surely, we have a test that can tell me if I’m going to have a heart attack?
To answer that question, you’ve got to understand two things. 1). The best (and only) way to prevent a heart attack is to change your lifestyle AND/OR start a statin medication. 2). Over 1/3rd of us will die of heart disease and 2/3rds of us will get heart disease in our lifetime. How worthwhile is a “screening” test when most of us will get the disease?
Okay, I get those two things…would you get to the tests?
Sure. I’ll list them:
Blood tests: high sensitivity c-reactive protein, Apo-lipoprotein B, NMR spectroscopy for cholesterol particle size and numbers.
Imaging tests: Ankle brachial indexing, flow mediated dilation, carotid artery ultrasound, and coronary artery calcium scoring.
One of my medical professors used to say that if there was a lot of tests to find the same answer, there was not a good test to find the answer.
Okay, so you’re telling me that of all those tests, that there is not one of them that can reliably tell me if I’m going to have a heart attack?
Actually the best test isn’t listed. It’s an online calculator that can tell you your risk of heart disease over 10 years. Is it perfect? No way and heck no. It’s good but it’s not great. So the question we should be asking is: Do any of these tests help the accuracy of the online calculator? The winner is coronary calcium scoring.
Sounds like an athletic event? I’m in. What is it?
The build up of plaque in our arteries contains calcium. A CT scan can “see” this calcium and identify how much and where it’s at. A scoring system has been created where you get a total score (i.e. 157) and are compared to people your same age and gender. Like golf, the lower the score the better. A score of 0 is the best and a score >100 is higher risk. If you’re above the 75th percentile for your age and gender, you’re also higher risk.
Sweet! Let’s go get a coronary calcium score right now!
Not so fast my friend. All medical tests should be done in the “right” person to avoid some things called “false positives” and “false negatives”—in other words, inaccurate results. Many medical facilities unfortunately offer this test to the entire population for a small fee ($100). They are then given a result and sent to their doctor who ultimately has no idea what to do with it because you’re not the right person for the test. The result may then lead to more and more unnecessary medical testing.
So who is the right person?
In short, the right person is someone with two things:
1). a 10 year risk of heart disease between 5-15% AND
2). who is hesitant to change their lifestyle or is trying to decide about taking a statin medication.
If I’m low risk by that risk score, should I get a calcium score?
Low risk people probably should not get a calcium score. In one study that looked at people about 61 years of age, people with a 10 year risk of heart attacks of <5% were very unlikely to have an abnormal calcium score >300 (4 in 100 people). In another study, younger people about 40 years of age with a risk score of <10% and a calcium score >100 numbered about 2 in 100 people.
What if I’m “intermediate risk”–how can the test help me?
The coronary calcium score can confirm you should take a statin or that you shouldn’t. In one study, of all the people who were recommended to take a statin because their risk was >7.5%, almost half of them had a coronary calcium score of 0 and over 10 years, this group of patients had 4 heart attacks in 1000 people. This makes people with a calcium score of 0 who are intermediate risk, very unlikely to benefit from a statin medication. A calcium score of 0 has been shown to be very low risk in other studies as well (study 1 and study 2).
So if I do the test, what’s a bad score?
Well, any coronary calcium is bad, but one study has shown that a score of 100 or more regardless of age or ethnicity, has been shown to have a heart attack rate of >7.5% over 10 years. Our current recommendations for people to take statins is that 7.5% threshold.
If I have a high score, does that mean I have blockages?
One of the biggest misconceptions about this test is that a high calcium score means you have clogged arteries. What the test ONLY tells you is your risk of having a heart attack over the next 10-15 years. It is recommended that people with scores >400 may get a stress test to screen for clogged arteries as their risk of having a blockage is slightly higher than the general population.
Okay, summarize for me, puleeeeaze!
In the end, if you’re intermediate risk by a risk calculator (5-15%) and you’re on the fence about changing your lifestyle AND/OR taking a statin, a coronary calcium score may help guide your decision. If you’re low or high risk, I would not get a calcium score. If your score is >100 or your score is >75th percentile for your age and gender, I would get very aggressive with preventive therapies.