Imaging tool reveals early
evidence of coronary artery disease

A doctor aims an electron beam at a patient's heart and discovers early evidence of calcium deposits on blood vessel walls that 10 years later may lead to heart attack. That once unlikely scenario is now possible, thanks to a new imaging machine Emory doctors are using to aid diagnosis of atherosclerosis, the sometimes deadly buildup of blockages in coronary arteries.

Randolph E. Patterson, director of cardiovascular imaging for the Emory Heart Center, is serving as medical director for the new Lifetech Cardiac Imaging Center-the first in Georgia to offer electron beam tomography, a quick, painless, noninvasive and inexpensive means of imaging the heart.

Lifetech electron beam tomography does not require the physical exertion that heart tests such as the exercise thallium stress test does. The complete test requires only five to 10 minutes of the patient's time and involves no needles, exercise, drugs, X-ray dye or undressing.

The special advantage of electron beam tomography over other noninvasive cardiac tests is that it detects the atherosclerotic disease process itself in the coronary arteries, Patterson said. Coronary atherosclerosis grows progressively over time, like a time bomb with a variable delay detonation time measured in years. Other noninvasive tests are not conducted until the disease progresses enough to narrow the openings in the artery by at least 50 percent-a narrowing that limits the maximum flow of blood through the artery. When blood flow does not deliver enough blood to supply the needs of the heart muscle, the heart may develop abnormalities that can then be detected by ECG or other methods. And unlike most other tests, electron beam tomography can detect coronary artery disease with equal accuracy in men and women.

"If we know who has the disease, we can offer very effective treatment," Patterson said. "The problem has been that we often don't know who has coronary atherosclerosis until the person has a heart attack, sudden death or develops symptoms. At these points, treatment options decrease or end. The electron beam tomography system provides an accurate test for coronary artery disease per se-not just its consequences-before symptoms appear."

The technology is an improvement over other computed tomography scanners for cardiac imaging because it acquires images more quickly-about 10-14 images per second, Patterson said. The fast scanner is required to "stop the motion" of the heart and its coronary arteries long enough to create an accurate picture.

"If a person has coronary athersclerosis, the American Heart Association recommends more intensive efforts to lower cholesterol levels and decrease other risk factors. Patients who know they have the disease are more highly motivated to change their lifestyle through improving diet, exercising and quitting smoking," Patterson explained.

Chicago resident and former heart patient Jim Dunfee, for instance, credits electron beam tomography with saving his life. Although he had no symptoms, the test nonetheless detected advanced coronary artery disease. Dunfee subsequently underwent six-vessel bypass surgery.
Heart disease is by far the leading killer of Americans-far more lethal than AIDS and all cancers combined. The American Heart Association estimates about 1.5 million Americans will experience a heart attack this year and about one-third will die. Coronary artery disease kills six times the number of women who die of breast cancer.

-Lorri Preston

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