News Release

Calcification process in aortic valves is responsible for blockages

Northwestern Memorial leads search for first medical therapy for aortic valve disease

Peer-Reviewed Publication

Northwestern Memorial HealthCare

(CHICAGO) –Bone-like cells similar to the cells found in the skeleton calcify in the heart's aortic valve and are responsible for the blockages that lead to the need for open-heart surgery to replace the aortic valve for tens of thousands of Americans, according to researchers at Northwestern Memorial Hospital and Northwestern University.

Study results, published in today's rapid access issue of Circulation: Journal of the American Heart Association are the first to present data demonstrating this process in human tissue. "These findings provide further support for the idea that statins may become the first medical therapy for patients with aortic valve disease," said lead author Nalini Rajamannan, M.D., a cardiologist at Northwestern Memorial Hospital in Chicago and assistant professor of medicine, The Feinberg School of Medicine at Northwestern University.

"Traditionally, the medical community thought aortic valve disease was a wear-and-tear phenomenon. For the first time, this line of research is pointing the finger at an active process in the valve," said Dr. Rajamannan. The study, which was performed on human aortic valves salvaged after replacement surgery and done in collaboration with Dr. Thomas Spelsberg's Laboratory in the Department of Biochemistry and Molecular Biology of the Mayo Clinic, demonstrated that the calcification in human aortic valve tissue is related to the specific biology in the valve.

This confirms the researchers' conclusions from an animal model of aortic valve disease, which was published in Circulation in June 2002. In that study, Dr. Rajamannan and her colleagues became the first to point to a phenomenon, similar to atherosclerois or hardening of the arteries, as being responsible for blockages in the aortic valve, the "outflow" valve of the heart. They found that high cholesterol levels can lead to fatty deposits in the aortic valve. These deposits may induce undifferentiated cells to transform to the bone-forming cells that calcify and narrow the aortic valve.

"These earlier studies also showed that statins, drugs commonly used to treat high cholesterol levels, greatly reduced the extent of atherosclerosis in the aortic valve," said Dr. Rajamannan. "These findings, combined with recent retrospective clinical studies that showed that statins in patients slowed the rate of progression for aortic valve disease, point to possible benefits of statin use in patients with early stages of the aortic valve disease process," she says. "Earlier statin use may delay that disease process and the need for surgical valve replacement."

Statins have been shown to increase the bones' calcium absorption, thus leaving less calcium floating in the blood to deposit in the aortic valve. In addition, calcium reduces cholesterol and inflammation, which also play a role in the process. Previously, no medical therapy has been proven to alter the progression of aortic valve disease.

Dr. Rajamannan's study also found that CT scans can be used to quantify the amount of calcification in the valves. Echo tests have been the gold standard for assessing aortic valve disease, but echo tests do not have the resolution to measure the amount of calcification present. "In the future, CT scans may prove to be a very powerful tool for predicting coronary events and determining if patients with a mild aortic valve murmur, who currently get no medical therapy, should begin statin therapy," she said.

Northwestern hopes to help launch a multi-center clinical trial in the near future to measure the effect of statins in patients with aortic valve disease.

In the meantime, study co-author Robert Bonow, M.D., chief of cardiology at Northwestern Memorial Hospital, president of the American Heart Association, and Goldberg Professor of Medicine at Northwestern University Feinberg School of Medicine says there's growing evidence of the benefits of statins in patients with aortic valve disease and high cholesterol. "This line of research is very exciting and will likely have a great impact on the way cardiologists practice."

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About Northwestern Memorial Hospital
Northwestern Memorial Hospital (NMH) is one of the country's premier academic medical centers and is the primary teaching hospital of Northwestern University's Feinberg School of Medicine. Northwestern Memorial and its Prentice Women's Hospital have 720 beds and more than 1,200 affiliated physicians and 5,000 employees. Providing care in a state-of-the-art facility, the hospital is recognized for its outstanding clinical and surgical advancements in such areas as cardiothoracic and vascular care, gastroenterology, neurology and neurosurgery, oncology, organ and bone marrow transplantation, and women's health.

Northwestern Memorial was ranked as the nation's 5th best hospital by the 2002 Consumer Checkbook survey of the nation's physicians and is listed in the majority of specialties in this year's US News & World Report's issue of "America's Best Hospitals." NMH is also cited as one of the "100 Best Companies for Working Mothers" by Working Mother magazine and has been chosen by Chicagoans year after year as their "most preferred hospital" in National Research Corporation's annual survey.


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