National Heart, Lung, and Blood Institute (NHLBI)-supported scientists report that ultrasonography, a non-invasive test, predicts the risk of heart attack and stroke in older persons with no cardiovascular disease symptoms.
The test was used to measure the thickness of the walls of two arteries in the neck. The result gave vital information beyond that available from an assessment of the standard cardiovascular disease risk factors, such as high blood pressure and high blood cholesterol.
The NHLBI is part of the National Institutes of Health. The finding appears in the January 7 issue of The New England Journal of Medicine.
"This study shows that ultrasonography has great potential in the prevention of heart attack and stroke," said NHLBI Director Dr. Claude Lenfant. "By identifying high risk patients, ultrasonography would allow doctors to provide aggressive treatment early."
Such treatment includes control of high blood pressure and high blood cholesterol, weight loss, increased physical activity, and aspirin and other drug therapies, he added.
Heart disease and stroke are the first and third leading causes of death among Americans. Each year, about 500,000 Americans die of coronary heart disease and about 160,000 of stroke. One in five Americans has some form of cardiovascular disease.
Ultrasonography is a relatively inexpensive, painless test in which sound waves above the range of human hearing are sent into the neck. Echoes bounce off the moving blood and the tissue in the artery and are then formed into an image.
The test is currently used in stroke prevention to diagnose advanced disease in the carotid arteries. The new study found that the test detects disease much earlier and identifies those at risk of heart attack as well as stroke.
The study involved 4,476 men and women, aged 65 and older, drawn from the NHLBI-supported Cardiovascular Health Study (CHS), a multi-center investigation of older Americans. CHS centers are in California, Maryland, North Carolina, and Pennsylvania.
About 40 percent of the ultrasound study's participants were men and 60 percent women. Blacks comprised about 15 percent of the participants; the rest were white. Participants were followed for an average of 6.2 years.
Scientists used ultrasound to measure the thickness of walls in the common and internal carotid arteries. The measures assessed patients' degree of atherosclerosis, a condition in which fat and cholesterol are deposited in artery walls. The walls thicken and become less flexible, and the narrowed opening impedes blood flow. If an artery becomes blocked, a heart attack or stroke can occur.
Atherosclerotic buildup is not uniform. By combining the measures from both arteries, scientists gained a more complete picture of the patients' conditions than either measure alone could yield.
Results showed that patients' risk of heart attack and stroke increased in direct proportion with the thickness of their artery walls. Those with the thickest arteries had an almost fivefold greater risk of heart attack or stroke than those with the thinnest measures.
Even after accounting for standard cardiovascular disease risk factors--such as cigarette smoking, high blood pressure, high blood cholesterol, and diabetes--patients with the thickest artery walls still had more than double the risk of a heart attack or stroke than those with the thinnest walls.
Dr. Daniel O'Leary, Radiologist-in-Chief, Department of Radiology, Tufts New England Medical Center (NEMC), and Dr. Teri Manolio, Director of the Epidemiology and Biometry Program at NHLBI, are available for comment on the study. To contact O'Leary, call the NEMC Press Office at (617) 636-0200; to contact Manolio, call the NHLBI Communications Office at (301) 496-4236.
NOTE for broadcast media: A demonstration of ultrasonography on a patient can be arranged through the NEMC Press Office.