Coronary Calcium Score of Zero: Reassurance, Limits and Repeat Scans

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• What coronary calcium shows
• A zero score depends on age
• The lipoprotein(a) caveat
• When he repeats the scan
• Why calcium stays after cholesterol lowering
• Endurance athletes and statin treatment
• Full Transcript

What coronary calcium shows

Coronary artery calcium is laid down where cholesterol has built up in the arteries. Dr. Anton Titov, MD, asks cardiologist Dr. Paul D. Thompson, MD, how a patient should understand a score of zero, who would benefit from the test and when it should be repeated.

Dr. Thompson explains that when cholesterol builds up in an artery, the body deposits calcium there, a little like making bone, and the artery hardens. He thinks the calcium itself is part of a healing process. What it tells the doctor is that the patient is making atherosclerosis.

A zero score depends on age

A zero calcium score is expected in a young person, Dr. Thompson says, even one with very high cholesterol levels. For that reason he does not use the test very often in young people, and he does not see a calcium score alone as the whole answer.

In an older person, a zero score means statistically only about a 4% chance of a heart attack or a stroke in the next 10 years, which he calls very low and very reassuring. He likens it to the Beatles song: a ticket to ride for about ten years. Still, a zero score does not totally remove the risk of a very high cholesterol level, because a young person with high cholesterol will put down atherosclerosis at some point. He would not ignore high cholesterol even with a zero score.

The lipoprotein(a) caveat

Lipoprotein(a) is one other caveat he raises. Dr. Thompson's group reported two patients, both women, with calcium scores of zero and calcium scores of one who had very tight narrowing in their heart arteries. Both had extremely high levels of lipoprotein(a).

He describes lipoprotein(a) as a type of cholesterol that can take good levels and make them ugly. He adds that it can probably produce cholesterol that does not have a lot of calcium in it, for some reason.

When he repeats the scan

How often to repeat the scan is a mixed question, in Dr. Thompson's view. If the score is zero, he repeats it in five or six years when the patient has a moderately high cholesterol level or a high lipoprotein(a), because he wants to know whether to treat that person.

The appearance of calcium is also a risk factor. A score that is still zero five years later is a very good prognostic sign. New calcium on later scans is not a terrible prognostic sign, he says, but it does show that the person is depositing cholesterol. If somebody has a high calcium score, he will repeat it.

Why calcium stays after cholesterol lowering

Calcium does not go away when cholesterol does. Dr. Thompson describes a study by his group on regression of cholesterol in the arteries: lowering a person's cholesterol level can take cholesterol out of the heart arteries, but the calcium score never gets better. Once calcium is put down, he says, it is stuck.

Endurance athletes and statin treatment

Two further points complete his answer. Endurance athletes, not just distance runners, can have a lot of coronary calcium. He says this really frightens them and is something to pay attention to, but being a distance runner can produce a lot of calcium.

Statins and cholesterol reduction also increase the calcium score. Because calcium is partly a healing mechanism, the body may put down more calcium as cholesterol is taken out of the plaque. Patients then ask what good the medication is if their disease seems to be getting worse. His answer is that the disease is becoming more stable because of the healing effect of the calcium. For that reason, when he treats someone aggressively with cholesterol-lowering medication, he does not repeat the scan, whether or not he knows they have coronary calcium.

Full Transcript

Dr. Anton Titov, MD: Coronary calcium score, what a calcium score of zero means for the heart. On your blog you wrote that a zero coronary calcium score means a low risk of heart attack. A high lipoprotein little a, you added, can make a zero score misleading. Professor Thompson, how should a patient understand a coronary calcium score of zero? Who would benefit from a coronary calcium test? When should the test be repeated?

Dr. Paul D. Thompson, MD: Those are a great set of questions. First of all, what is coronary artery calcium? When you put cholesterol in your heart arteries or any arteries, the body tries to heal it.

Dr. Paul D. Thompson, MD: One of the ways it heals it is by putting calcium down there. It deposits calcium. It is kind of a little bit like it makes bone in the artery.

Dr. Paul D. Thompson, MD: It hardens the artery. The calcium itself, we think, is part of a healing process, but what it tells you is that this patient, this dude, this dudette, is making atherosclerosis, because they have got deposits of calcium in their coronary arteries. Now, if you are young, a zero calcium score is expected, right?

Dr. Paul D. Thompson, MD: A zero calcium score is expected if you are quite young. So you can have very high cholesterol levels and a zero calcium score if you are a young person. That is why I do not use them very often in young people, and it is also why a calcium score alone is not the whole answer.

Dr. Paul D. Thompson, MD: If you are older and you have a zero calcium score, that means statistically that you only have about a 4% chance of having a heart attack or a stroke in the next 10 years. That is very low. That is very reassuring.

Dr. Paul D. Thompson, MD: Now, it does not totally mitigate the risk of a very high cholesterol level, because if you are young, have no calcium, and you have a high cholesterol level, you are going to put down atherosclerosis at some point. But a zero calcium score, I say it is like the Beatles song: "You have got a ticket to ride." You have got a ticket to ride for about ten years if you have got a zero calcium score. But I would not ignore high cholesterol even with a zero calcium score.

Dr. Paul D. Thompson, MD: Now, there is one other caveat, or one other disclaimer. We reported two patients with calcium scores of zero and calcium scores of one who had very tight narrowing in their heart arteries, and what did they have? They had extremely high levels of lipoprotein(a).

Dr. Paul D. Thompson, MD: They were both women. They had very high levels of lipoprotein(a). Remember, lipoprotein(a) is a type of cholesterol that can take good levels and make them ugly.

Dr. Paul D. Thompson, MD: It can also probably cause a type of cholesterol that does not have a lot of calcium in it, for some reason. Now, another question that comes up often is: how often should you repeat the coronary artery calcification score? It is mixed.

Dr. Paul D. Thompson, MD: If the score is zero, I will repeat it in five or six years if the patient has a moderately high cholesterol level or a high lipoprotein(a), because I want to know: should I be treating that person? The appearance of calcium is also a risk factor. If someone has a zero score five years later, zero five years later, that is a very good prognostic sign.

Dr. Paul D. Thompson, MD: But if they start to have more calcium on subsequent scans, that is also not a terrible prognostic sign, but it does tell you they are depositing cholesterol. Now, if somebody has a high calcium score, I will repeat it. We did a study where we looked at regression, going away, of cholesterol in arteries.

Dr. Paul D. Thompson, MD: So cholesterol goes away in the arteries. If you lower somebody's cholesterol level, you can take cholesterol out of their heart arteries, but their calcium score never gets better. Once that calcium is put down, it is stuck.

Dr. Paul D. Thompson, MD: Now, the other two things you need to know: distance runners, endurance athletes, I should say endurance athletes, not just distance runners. Endurance athletes have a lot of coronary calcium. We will probably come and talk about that, but distance runners can have a lot of coronary calcium, and that really frightens the dickens out of them.

Dr. Paul D. Thompson, MD: It is something that we have to pay attention to, but you can get a lot of calcium from being a distance runner. The other important thing about a coronary calcium score is that statins and cholesterol reduction increase the score. What?

Dr. Paul D. Thompson, MD: I thought this cholesterol drug, this statin, was reducing my risk of heart attack, and yet my calcium score is going up. That is because calcium is partly a healing mechanism. So if you are getting the cholesterol out of the plaque, taking it out of the coronary artery, the body may repair that by putting down more calcium.

Dr. Paul D. Thompson, MD: So if I am treating somebody aggressively with cholesterol-lowering drugs, and I know they have coronary calcium, and even if I know they did not have coronary calcium, I am not going to repeat that scan, because that scan could show that the calcium is larger, that they have more calcium. And the patient often says, "Well, what good is this drug? My disease is getting worse."

Dr. Paul D. Thompson, MD: No, your disease is getting more stable because of the healing effect of the calcium.