Wednesday, July 7, 2004

Don’t overrate electron beam CT

Guest opinion by Dan Fairman

Dr. Dan Fairman is a physician in the Wood River Valley.

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I love to read medical articles in non-medical sources, such as newspapers and magazines. At times, I learn something that is being acutely released in the press, sometimes before it has had a chance to get to physicians. Late breaking news from the New England Journal of Medicine is an example: sometimes results from trials are released to the general press before the article has been printed in the Journal.

Other times I’ll read of new drugs or treatments or trends in medical care that don’t exactly make it to the mainstream medical press. Some of these do have some validity, and some need to be taken with a grain (or a pound) of salt.

So imagine my surprise at reading an article by none other than Warren Miller on the benefits of electron beam computed tomography, or EBCT, in the detection of heart disease! Warren Miller, noted skier and filmmaker: I didn’t know he’d also received a medical degree along the way!

First, let’s give some background. EBCT is a fascinating application of technology. The ability to image the beating heart is truly an advancement in radiology, and with this advancement, calcification has been seen in arteries surrounding the heart. Calcification occurs when atherosclerosis occurs over time, and reflects areas of plaque that have hardened. Interestingly and importantly, this is not the kind of plaque that will cause a heart attack. These areas that have calcified are not the type of soft plaque that will rupture and cause heart damage or death. Soft plaque is not visible on the EBCT.

So, what is the value of the EBCT, and what is the value of coronary artery calcification? Simply put, no one is truly sure. Daily physicians here and across the nation have patients request a "heart scan", or will present to our offices with an EBCT that they had done "because they should". Suppose you do have a heart scan, and it shows calcifications. The physician’s first question is whether these are significant or not, that is, whether there is limitation of blood flow to the heart. To find that out you’ll be scheduled for a different test, which is going to be a functional test, such as a treadmill, sestamibi treadmill, or stress echocardiogram.

Suppose you don’t have heart artery calcification. Unfortunately, this doesn’t mean you don’t have heart disease: it only means that any plaque you do have hasn’t calcified yet. You still could be at risk for a heart attack.

The American College of Cardiology, which is the national organization of cardiologists, is also still unsure of the value of the EBCT test. As one cardiologist put it, ‘It’s a technology in search of an application".

As is true with a number of new devices and technologies, there are people who will claim that this test saved their life. There are cases that are really true; I have several patients who had the test done, were found to have calcifications, and subsequent tests indicated a need for stent placement or even bypass surgery, and you could claim the test saved their life. Alternately, they could have gone to their doctor, had their cholesterol and blood pressure measured, had a treadmill, and gotten the same result. I also have other people who have had abnormal EBCT tests with normal follow-up testing; for those people I recommend the same things as if they didn’t have an abnormal EBCT: change in diets, increased exercise, and control of risk factors like cholesterol, smoking, and blood pressure.

So, is Warren Miller right? Maybe. He’s sure a good skier, and I love his films. Your insurance company won’t pay for the EBCT because it’s still not a proven technology (besides the fact they don’t want to pay for anything, anyway). For now, most physicians think that EBCT is interesting, and fascinating, but it’s not the perfect answer to the question.

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