If you’re health conscious, you probably track a whole slew of numbers: blood pressure, total cholesterol, LDL, HDL, triglycerides, weight and waist circumference. These numbers represent well known risk factors for heart disease. If your numbers are normal or below, you congratulate yourself; if they become too high, you start making lifestyle changes, and your doctor may prescribe medications.
Recently a new test, generating a new set of numbers, appeared on the scene: the coronary artery calcium scan. Your doctor probably didn’t mention it, but you may have noticed ads and promotions offering walk-in scans. Before you accept any such offer, you should learn some facts and understand that neither the American Heart Association nor the American College of Cardiology recommend the test for everyone.
That’s not because there is any question about the validity, accuracy or safety of the test. Using electron beam technology (EBCT) or multidetector computer tomography (MDCT) , the scan is fast enough to take a picture of a beating heart. Unlike some heart studies, it requires no medication, injections or dyes and does not expose the body to large doses of radiation. A full study, which can be completed in about 10 minutes, gives an accurate measurement of the calcium that has formed in blood vessels, probably as a reaction to chronic inflammation.
A Sign of Aging Plaque
Not all plaques contain calcium, but those that do are generally older and larger, more likely to rupture and lead to a heart attack. Although calcium on its own does not cause damage, it is generally considered a marker for advanced artery disease.
What is obtained from the test is a number–ranging from 0 to 1,000 or more–that is called an Agatston score. It’s believed to be a good indication of the extent of atherosclerosis and, as a result, a person’s risk of a heart attack.
A score of zero is good; anything over 100 indicates a likelihood of heart disease. The higher the number, the higher the risk. So why shouldn’t everyone want to know his or her calcium score?
One reason is cost. The cost of a scan has come down to about $100 but is usually not covered by health insurance. And while the radiation exposure in each scan is relatively modest (the equivalent of 10 chest x-rays or 2 mammograms), the risk of cancer from cumulative radiation is great enough that you don’t want to expose yourself needlessly.
IF YOUR OVERALL RISK OF HEART DISEASE IS LOW, then the test is probably not for you. If you’re younger than age 55, have normal weight, blood pressure and cholesterol and don’t smoke, then your heart attack risk is less than 10 percent over the next 10 years.
No test is perfect. You could get a high score even if your arteries are not blocked. And that would lead to further unnecessary testing as well as some anxiety even though your risk is low.
On the other hand, even significantly blocked arteries do not always contain calcium, so a lower score does not necessarily mean you are home free.
IF YOUR OVERALL RISK IS HIGH, you also should skip the test. Diagnosis and treatment are based largely on the traditional risk factors that grew out of the Framingham Heart Study: age, gender, cholesterol, smoking and blood pressure. Through these factors, a person could be identified as having a heart attack risk of 20 percent or greater over the next 10 years–considered high risk.
This high-risk category also applies to persons having symptoms such as chest pain or shortness of breath and those who have already had a heart attack, heart surgery or balloon angioplasty.
These individuals should already have a treatment plan to lower their risk of a heart attack through lifestyle changes and medications. A coronary calcium score should not add any information that could change that plan.
IF YOU HAVE A MODERATE RISK, then your doctor may want you to have a coronary calcium scan. This category includes persons with a 10-year risk ranging between 10 and 20 percent.
In practice, this means
• age between 55 and 65 and/or
• borderline high blood pressure or high cholesterol.
Smokers are at moderate risk regardless of their other risk factors.
For persons at this risk level, the coronary calcium score gives the doctor information about who needs treatment and what that treatment should be.
You might also benefit from a coronary calcium scan if you have had symptoms such as chest pain or shortness of breath. A scan will help a doctor determine whether these symptoms are heart-related and the potential seriousness of the problem.
For a person considered at moderate risk, a coronary calcium score of more than 100 is cause for concern. And studies show that a high Agatston score provides good motivation for lifestyle changes such as weight loss, smoking cessation and compliance with the treatment regimen.
A 2003 Illinois study found that men with the highest coronary calcium scores were four times more likely to have a heart attack or die from heart disease compared to those with the lowest scores. And the high scorers were 26 times more likely to need heart surgery or angioplasty. While this study had flaws, it is generally accepted as validation of the scan’s value in detecting future risk.
A later study published in The Lancet [August, 2011] concluded that calcium scans may be more effective in predicting heart risk than CRP (c-reactive protein) tests in predicting heart attack risk and determining which patients might benefit from cholesterol-lowering statins.
Other studies have confirmed that coronary calcium is a strong predictor of cardiovascular disease. In the MESA (Multi-Ethnic Study of Atherosclerosis) study, for example, subjects with a coronary calcium score of greater than 100 were seven times more likely to have heart events. Since traditional risk factors fail to identify a significant number of heart attacks, it’s helpful to have another effective tool.
If you are one who might benefit from a coronary calcium scan, the best approach is to go through your primary care doctor. He or she has a comprehensive picture of your overall health and lifestyle and knows how to interpret the results in light of your other risk factors.
REFERENCES:
Hailhem M. Ahmed, et al, “Low-risk lifestyle, coronary calcium, cardiovascular events, and mortality: results from MESA,” American Journal of Epidemiology, 2013;178(1):12-21.
“Coronary calcium scan,” WebMD Medical Reference from Healthwise, last updated April 25, 2011.
“Counting coronary calcium: are the new scans right for you?” Harvard Men’s Health Watch, February, 2004.
Raimund Erbel and Matthew Budoff, “Improvement of cardiovascular risk prediction using coronary imaging,” European Heart Journal, 2012;33(10):1201-1213.
Mayo Clinic Staff, “Heart scan (coronary calcium scan),” MayoClinic.com, May 1, 2013.
Reed Miller, “Patients with high calcium score more likely to lose weight, take statins,” Heartwire, March 24, 2012.
NIH, “What is a coronary calcium scan?” National Heart, Lung and Blood Institute.
Ally Pen, et al, “Discordance between Framingham risk score and atherosclerotic plaque burden,” European Heart Journal 2013;34(14):P1075-1082.
Crystal Phend, “Calcium scans pick up controversy in cardiology,” MedPage Today, August 26, 2011.
Shelley Wood, “Finally, AHA’s coronary calcium and CT statement sees the light of day,” Heartwire, October 5, 2006.
12/13/2013
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