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November 10, 1999

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Johns Hopkins Researchers Report from this Month's American Heart Association Meeting

The following news tips are based on abstracts or posters to be presented at the American Heart Association's 72nd Scientific Sessions, held Nov. 7-10 in Atlanta.

WOMEN'S WEIGHT, RACE DETERMINE IF HORMONE REPLACEMENT THERAPY IS BENEFICIAL

Postmenopausal women's cholesterol levels, race, weight and whether they smoke may indicate to physicians how effective hormone replacement therapy (HRT) would be in protecting them against heart disease, according to research by Johns Hopkins and the University of Maryland.

In a search for characteristics that would predict the effectiveness of HRT, researchers returned to the patient database from the Postmenopausal Estrogen/Progestin Interventions (PEPI) trial, a three-year study of 875 postmenopausal women designed to assess the effects of HRT regimens on heart disease risk factors. Results from PEPI were published in 1995.

They examined increases in high-density lipoprotein or "good cholesterol," decreases in low-density lipoprotein or "bad cholesterol," and decreases in triglycerides (molecules needed to make fats). Overall, women with high cholesterol profiles benefited the most from HRT. African-American women and smokers saw fewer benefits from HRT than women of other races and non-smokers. Thinner women saw greater decreases in bad cholesterol, perhaps because heavier women need a higher dose.

"There is consistent evidence that HRT alters cholesterol levels in postmenopausal women, yet individual patient responses vary substantially," says Roger S. Blumenthal, M.D., director of Hopkins' Ciccarone Center for the Prevention of Heart Disease and an author of the study. "These findings may provide useful information to clinicians in identifying patients who will benefit most from HRT."

AFRICAN-AMERICANS' EXERCISE PATTERNS COULD INDICATE HEART DISEASE

High blood pressure triggered by exercise tests could indicate early heart disease in apparently healthy adults, according to a Johns Hopkins study.

Researchers studied 99 African-American adults ages 39 to 55 with no symptoms of heart disease but whose brothers and sisters had been diagnosed with early heart disease. They measured blood pressure of study participants at rest and while walking on a treadmill.

Of 43 people with normal readings at rest, 47 percent had a rise in blood pressure during exercise. Of the 56 people who had high blood pressure at rest, 77 percent had even higher rises in pressure during exercise. All 15 diabetics in the group experienced a rise in pressure during exercise, and overweight siblings were 3.4 times more likely to experience exercise-induced high blood pressure.

High blood pressure during exercise testing is a predictor of enlarged heart muscles and future cardiovascular events such as heart attack or stroke.

"These results indicate a surprisingly high prevalence of high blood pressure during exercise, far greater than the 5 percent we anticipated," says Lisa R. Yanek, M.P.H., a researcher with the Johns Hopkins Center for Health Promotion and author of the study. "This suggests a need for behavior modification when heart disease runs in families, such as weight loss and improved blood pressure control."

NEW USES FOR MRI PROVIDE CLEAR VIEW OF PLAQUES IN THE AORTA, BLOOD FLOW THROUGH THE ARMS

Two adaptations of magnetic resonance imaging (MRI) technology developed by doctors at Johns Hopkins show promise in the diagnosis and treatment of early heart disease.

In the first, transesophageal MRI (TEMRI), a receiver is threaded through the nose to the esophagus to reveal plaque building on the aorta, the heart's main artery. Researchers led by Kendrick Shunk, M.D., Ph.D., and Jo o A.C. Lima, M.D., compared TEMRI to echocardiography (technology that uses ultrasound waves to investigate and display the action of the heart as it beats) in nine patients with aortic plaque and two healthy volunteers. TEMRI was found to be more powerful in detecting plaque and better at characterizing the extent of its damage to the heart. These pictures can mean that cardiologists may be better able to predict which patients are more vulnerable to a coronary event like a heart attack.

The second adaptation, phase contrast magnetic resonance angiography, looks at the flow of blood through vessels in the arms. After a blood-pressure-like cuff is placed around the patient's upper arm, physicians use MRI to measure the dilation of the blood vessels and the "shear stress" generated by the force of blood flow against endothelial cells, the cells lining the inside of the vessels. Normally, the chemical nitric oxide is produced by endothelial cells; it causes coronary arteries to widen to increase blood flow to the heart and other muscles during times of stress. In people with coronary artery disease, however, the arteries constrict, limiting blood flow and possibly contributing to ischemia and heart attack. Researchers led by Harry Silber, M.D., Ph.D., successfully tested this method in 18 healthy adults without cardiac risk factors, completing the first study of MRI to measure endothelial function in humans. The technique could lead to the earliest detection of heart disease in people at risk.

"MRI technology offers incredible opportunities to see evidence of heart disease at its earliest stages and to intervene before patients are in trouble," says Lima, associate professor of medicine and radiology at Hopkins.

Related link:
American Heart Association 72nd Scientific Sessions
http://aha99.bluedot.com


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