Coronary Artery Calcium Scans Are Not the Answer

Medical tests can never be good or bad. The problem is always the humans who misuse the test. For now, though, I argue (again) against using CAC scans

Since Andrew Foy and I wrote our Case Against Coronary Artery Scans in an academic journal, the test has only increased in popularity. Grin.

The imaging test measures the amount of calcium in the coronary arteries. It’s not covered by health insurers, but smart businesspeople have placed the cost at a manageable $100—which is only a fraction of what you’d be billed for a medical grade CT scan.

I write now because of Twitter activity amongst popular and rich business/tech people. Here is a Tweet from Brad Gerstner, the founder of Altimeter Capital.

Mr Gerstner has been on the super-popular All In Pod to explain why everyone under 40 should have a coronary calcium scan.

Mr. Gerstner shared this email as evidence to support the use of CAC imaging.

“Good Morning Fellas. I had a Cardiac Calcium Score test performed a few months ago and it was off the charts at 460 and triggered an appointment with a cardiologist. I then had a nuclear stress test and echocardiogram, which turned out mostly normal, except for a small area where they thought I might have some blockage.

Fortunately, we decided to do a CT angiogram and it revealed that I had two vessels that were 75% blocked. On December 29th, I went in for a heart catheter procedure. Once they were able to evaluate the vessels, I had one artery that was 75% blocked and the other was 90% blocked. I ended up with several heart stents to fix these issues.

Everyone kept asking if I had shortness of breath or chest pain. The answer was always NO, because I NEVER had any symptoms. I probably would have had a heart attack or worse within several months if this had gone unchecked.

Having the cardiac calcium score test most likely saved my life. Like Gersh says - I urge everyone to have one done immediately. My doctor never recommended doing a Cardiac Calcium Score - they just kept pushing cholesterol medicine to prevent heart issues. I believe that the medical community should routinely recommend this test, just as they would a colonoscopy or a mammogram for screening purposes.

Why this is wrongheaded?

Let’s first set out that this post-test cascade is common. But it is not what experts recommend.

The academic proponents of CAC scans strongly recommend CAC scans only to guide decision-making about using primary prevention therapies, such as statin drugs, in medium risk people. (Low-risk and high-risk people face easy decisions about using preventive techniques, goes the thinking.)

The typical example for a CAC scan is a middle-aged person with an elevated cholesterol level. This person may have a 10-year risk of 6%. The doctor suggests a statin. But the patient is unsure. A CAC scan may help this man or woman decide. If the CAC score is zero, proponents of CAC would say, he/she could avoid statins for now. If the CAC score is high, proponents would argue that the 10-year risk is now high enough to warrant statins.

That is it. That is all that CAC scans are for. Nothing else. Nada.

But that is almost never what CAC scans are used for. I practice cardiology in a typical medium-sized American city, and here, CAC scans are used for diagnosis and often start the cascade that Mr. Gerstner described above.

Positive calcium scores scare patients and doctors. Fear shreds good decision making. Coronary calcium often leads to a stress test. Better check it out; heart disease is a leading killer. A positive (or equivocal) stress test then leads to a coronary angiogram. If there are partial blockages, doctors often put in stents. I’ve even seen totally asymptomatic people get bypass surgery because of a CAC scan.

That cascade belies the mountain of evidence that shows that opening blockages with stents or bypassing them with surgery in stable patients does not reduce the risk of future heart attack or death over medical therapy alone.

Pause there. Read that paragraph again. It is the crux of the problem.

A coronary stent can be lifesaving when placed during a heart attack but has zero effect on future outcomes when placed in a stable patient.

It’s counter-intuitive but it is what the evidence shows. RCTs such as BARI-2D, COURAGE and ISCHEMIA studied thousands of patients with coronary disease and show that opening or bypassing stable blockages does not reduce future events over medical therapy alone.

Notable also is that COURAGE authors have published many substudies looking for a group that benefits from stents. They found no patient group that does any better with stents. Not even those with “widow-makers.”

The Argument Against CAC scans

My piece with Dr. Foy is open access. Our argument is basically fourfold.

• Even if you believed CAC scans could reliably enhance risk prediction (we don’t), it would hardly help people decide. Can a normal person discern a difference in 10-year risk of 5% vs 9%? Doubtful.

• The CAC zero argument is most worrisome. Proponents of CAC argue (from observational data) that zero coronary calcium confers a very low future risk. This study found that a sizable fraction of obstructive coronary disease occurred among young people without CAC. Ouch.

• CAC scans too often lead to either costly or harmful cascades. Recall that the writer above who feels saved by having coronary stents now has to take an anti-platelet drug long-term. What happens when he has to have back surgery in the future? I’ve seen patients have stent thrombosis when the anti-platelet drug is interrupted. That is an awful outcome because going from a 0% blockage to 100% is terrible.

• CAC scans expose people to radiation. It’s not a lot, but it is radiation.

Conclusion

In a better world, where everyone understood that chronic stable coronary disease was actually chronic and stable, CAC scans would not be problematic.

A medical test is never the actual problem. The problem is always the humans that misuse the results of the test.

But I am a pragmatist. Until society has learned to better understand coronary artery disease, I will argue strongly against doing CAC tests. Because you can’t unsee the results.

Many ask what they can do to avoid dying from coronary heart disease.

The answer is simple but boring. Eat well. Exercise regularly. Don’t smoke. Don’t ignore symptoms. And you should know that statin drugs reduce your risk by about 25%.