May 29, 2000 -- Too much cholesterol in the blood appears to raise a person's risk of developing heart valve disease, according to a study in today's Circulation: Journal of the American Heart Association.
The study found that heart valve disease is also more likely to occur in men and individuals who smoke. Heart valves perform the vital job of maintaining the heart's blood flow in the correct direction.
Elevated cholesterol levels lead to atherosclerosis, the collection of fatty deposits that block blood flow, triggering a heart attack or stroke. But researchers found that elevated cholesterol was also a risk factor for developing aortic valve narrowings. The aortic valve allows blood to pass from the main pumping chamber of the heart (the left ventricle) to the aorta, the heart's largest artery.
"The strategies that we use to prevent atherosclerosis in the blood vessels may help prevent valve disease," says Ramdas G. Pai, M.D., currently director of echocardiography at King Fahd National Guard Hospital in Riyadh, Saudi Arabia. He conducted the study as part of a team at Loma Linda VA Medical Center and Loma Linda University in Loma Linda, Calif.
Diagnosing valve narrowing -- or aortic stenosis -- is often difficult because not all individuals develop symptoms, which include chest pain, labored breathing and fainting. Severe cases are treated surgically by valve replacement. In some cases, there is no clear consensus about treatment, in part because factors affecting the progression of the disease have not been clearly defined.
Researchers conducted the study to look for factors that might predict which individuals are most likely to develop valve problems. They used echocardiography, an imaging technique that uses sound waves to study the function of the heart, to check the size of the aortic valve opening. The size measurement is called the aortic ventricular area (AVA). The smaller the AVA, the more severe the aortic stenosis.
By comparing measurements taken several years apart, researchers could determine whether the aortic narrowings were worsening and the speed of disease progression. The disease was accelerated by factors such as current smoking, high cholesterol levels and male gender.
"If disease progression can be slowed by interventions such as lowering cholesterol and cessation of smoking, this would potentially reduce the number of deaths from the disease and the need for aortic valve replacement," he says.
About 78,000 valve procedures were performed in 1997, and the number is expected to increase as the population ages.
In this study, 170 patients (132 patients were men and 38 were women) ages 62 to 80 were examined. The individuals were divided equally into two groups. Those whose AVA shrank 7 percent or more per year were classified as "rapid progressors," whose aortic stenosis was quickly worsening. Those whose AVA diminished by less than 7 percent a year were classified as "slow progressors."
The rapid progressors were more likely to be men, and current smokers. They also had higher serum creatinine levels. Serum creatinine is an indicator of kidney function; higher levels suggest less effective kidney activity. Eleven percent of these individuals were on dialysis, a greater proportion than the slower progressors (3 percent).
The rapid progressors also had higher calcium levels in their blood. "A higher blood calcium level, even within the normal range, seems to be associated with the progression of aortic stenosis," Pai says.
The relevance of this observation will require more study, says Pai.
"The fact that aortic stenosis progression is influenced by cholesterol and other biochemical factors indicates that the disease progression may potentially be retarded by modifying these risk factors," Pai says.
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