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The truth about medical tests for the heart

A version of this commentary appeared in the Halifax Chronicle Herald, Victoria Times Colonist, and the Winnipeg Free Press

The brochure’s pitch puts it plainly: “Vascular health screening can detect injured arteries before you have a heart attack or stroke.”

Wouldn’t it be great if you could just get some sort of heart or blood vessel scan to prevent an early death?  As the most important organ in your body, your heart gets a lot of attention from the medical community and that’s why finding heart disease early, before it strikes you down, seems so attractive.

Lucky for you there are oodles of heart and blood vessel scanning technologies offered to people who don’t yet have any signs of heart disease.

For $690 Vancouver’s Canada Diagnostic Centre will sell you a high-tech heart scan, and similar services are available in most of Canada’s major cities.  The goal of one such scan is to look for “calcified plaque build-up in the heart’s arteries.” Apparently you could have such plaque and feel fine, even do well in the standard exercise stress test and exhibit no signs of disease — though the plaque, they say, correlates to your “risk of future coronary disease.”

Information on the company’s website says that a heart scan (also known as Coronary Artery Calcium Scoring) would be appropriate for men 40 and over or women 50 and over and can help “provide an overall picture of your heart health.”

Now many of us would like the reassurance such a picture might provide but at the same time what do the experts say about examining our coronary arteries this way? Unfortunately, they aren’t sure.  Artery calcium scoring hasn’t been studied enough yet.  Nor have many other types of heart scans that are being sold through these kinds of private clinics.

“Harms outweigh the benefits”: US task force

Consulting the recommendations from the United States Preventative Services Task Force (USPSTF), considered by many the evidence bible on screening,  reveals some surprises.  In fact, USPSTF recommends against artery calcium scoring and three other types of heart screening tests for healthy people including electrocardiography (ECG), exercise treadmill testing (ETT), and electron-beam computerized tomography (EBCT). All of these tests, according to the USPSTF should not be done routinely because the “harms outweigh the benefits.”

That goes contrary to what most of us believe: that it’s better to “test early and test often”  to avoid an early death from preventable disease.  What recent research has found instead is that even when a scan shows something suspicious, finding it early doesn’t necessarily lead to better health.  A May 2011 study in the Archives of Internal Medicine found that people who had heart scans ended up taking more medications and having more surgery, yet they didn’t live any longer, compared to those conventionally screened.

“Excessive and not necessary” for healthy patients

Dr. John McEvoy is a researcher at the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease in Baltimore and authored the Archives screening study. While heart testing might be useful in the right setting (like when someone has chest pain or other heart symptoms), Dr. McEvoy says the evidence doesn’t support doing heart screens on healthy people.

In his study, about 20 per cent of those patients who were scanned were told they had cholesterol buildups in their arteries (also called atherosclerosis) and they ended up taking a lot more drugs (aspirin and cholesterol-lowering drugs), had more tests and more major heart interventions. The scanned patient had more referrals for more tests, and had more heart bypass and stenting operations. But they were no healthier after a year and a half of observation.

Acknowledging that it might take longer than 18 months to see any effects, he noted that exposure to radiation and the contrast dye can be harmful. Excess radiation exposure may cause cancer and the contrast iodine used in the screening can lead, in some cases, to kidney failure.

Even though preventative heart scans are considered “excessive and not necessary” by experts in the field, it doesn’t stop physicians or private clinics from offering these services.

So what’s a patient to do?  Certainly the “better safe than sorry” axiom is a strongly held belief and may drive many of us to get heart screening exams, but the research sends out a competing message, perhaps best characterized as: “chill out.”

If you really want to do something to prevent heart disease, instead of spending hundreds of dollars for a high-tech heart screen, you could try something really radical.  How about following the perennial lifestyle advice that most doctors hand out: stop smoking, get regular exercise, cut down on fat and salt, drink in moderation and manage your stress.

There, I just saved you $690 and perhaps a mountain of unnecessary worry.

Alan Cassels is a drug policy researcher at the University of Victoria and an expert advisor with EvidenceNetwork.ca. 

April 2012

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