Putting a patient on a treadmill and then measuring blood pressure, breathing and heart rates is an accepted way for physicians to detect signs of coronary artery disease. But stress testing only picks up blockages that are at least 60 percent obstructive, notes cardiologist Roger Blumenthal, M.D. "By then, the horse is already out of the barn with significant disease of the arteries," and it may be too late to use preventive measures to avoid invasive bypass surgery or angioplasty—expanding the narrowed artery with a balloon. To get around that problem, cardiologists here are using a new type of CT scan, called Electron Beam Tomography, or EBT, that is allowing them for the first time to observe signs of coronary blockages before chest pain and shortness of breath start occurring. 
| An EBT Scan, says cardiologist Blumenthal, is the first proven, non-invasive way to detect very early development of plaque in the arteries. |
Blumenthal says that until now there’s been no proven, noninvasive way to see this very early development of plaque in the arteries EBT, which is performed in less than five minutes on a fully clothed patient lying on an open table, works by taking stop-action images of the beating heart, 20 times faster than any previous method. The technique produces images of calcium buildup, which shows up as white specks on the walls of arteries, before these specks develop into calcified plaque. By determining the amount of coronary calcification—the tip of the atherosclerotic iceberg—cardiologists can better predict the person’s risk of a cardiac event over the next five years. "If indeed you have coronary calcification, you may not have a significant amount of rust, or obstruction, in the pipes," Blumenthal says. "But we can clearly see abnormalities that predict future blockages." That’s exactly the information that’s necessary to prescribe preventive treatment to a symptom-free patient and reduce the risk of a debilitating heart attack. About 650,000 of the estimated 1.5 million heart attacks this year, according to the American Heart Association, will be the patient’s first indication of coronary artery disease. One in four of those first-time victims will die. "With a coronary calcium scan, along with a good history, physical and lipid profile and other blood tests, we can determine what an asymptomatic person’s risk is with a high degree of certainty," Blumenthal says. "And knowing where they stand may motivate patients to rev up their lifestyle with exercise and diet." -- Gary Logan
Hopkins Medical News, Spring/Summer 2001 |
