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Study: Heart Scan Not Useful As Statin Screen

March 17, 2014
Written by: , Filed in: Cardiac Imaging
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Should patients with high cholesterol get a coronary artery calcium (CAC) scan, just to make sure plaque really is building up in their coronary arteries, before deciding whether to go on statin medication?

No, say researchers at the University of California, San Francisco—at least as long as statins are cheap and don’t reduce the patient’s quality of life.

The researchers created a cost-benefit statistical model based on data from the Multi-Ethnic Study of Atherosclerosis, among other sources. For 10,000 hypothetical 55-year-old women with high cholesterol and a 10-year coronary heart disease risk of 7.5 percent, the model predicted that statins would prevent 32 heart attacks, create 70 cases of muscle disease as a side effect, and add 1,108 years to the women’s total life expectancy.

Using a CAC scan to target statin treatment to the 2,500 women with arterial plaque would provide 45 percent of the benefit (an additional 501 total years of life expectancy), but at a cost of $2.25 million and nine cancers caused by radiation from the CT scan.

Both scenarios assumed low statin costs (13 cents per pill) and no reduction in quality of life from the drug. Only if statins cost $1 or more per pill and reduced the quality of life did CAC screening become cost-effective. Otherwise, the researchers said, we should skip the scan and put everyone with high cholesterol on statins.

Mark Pletcher, MD, lead author of an article about the study that was published online last week in Circulation: Cardiovascular Quality Outcomes, admitted surprise at the results:

The prevailing wisdom is that if you have a test that predicts heart attacks, you should use it.

He added, “But even a test that is strongly predictive of future events, like a coronary artery calcium scan, does not itself improve outcomes. If it is used to keep some people off of statins that would otherwise take them, then fewer people will get protection from using statins, and more people will have heart attacks.”

Dr. Pletcher is an associate professor of epidemiology and biostatistics and also of medicine at UCSF. He was quoted in a university news release.

Yeah, OK, but …

Because of my high cholesterol (253), my doctor wants me on statins. I’m leery of side effects, so I’m trying (not very rigorously, I admit) to lower my cholesterol by other methods. If a CAC scan showed plaque buildup, would I change my mind and fill that statin prescription?

Yeah, I think so. And that’s something a statistical model can’t address: Would actual evidence of heightened heart attack risk be more persuasive than theoretical evidence (statistics)? Would images of arterial plaque, supplied by a CAC scan, get more people to accept a life-extending statin regimen?

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Related CME seminar (up to 12 AMA PRA Category 1 credits™): UCSF Cardiovascular & Pulmonary Imaging


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