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A new study from Weill Cornell Medical College supplies "important missing links" in our knowledge of "the causes, mechanism, and composition" of the scarring that occurs in heart muscle when there is cardiac valvular disease, according to the lead author, Dr. Jeffrey S. Borer. The study suggests possible approaches to preventing scar formation and thus reducing both the risk of heart failure and the need for valve operations.

Published in a recent issue of Circulation, a journal of the American Heart Association, the study is a product of Weill Cornell's Howard Gilman Institute for Valvular Heart Diseases, of which Dr. Borer is a Director.

Dr. Borer, who is also the Gladys and Roland Harriman Professor of Cardiovascular Medicine at Weill Cornell Medical College and Attending Physician at NewYork-Presbyterian Hospital's Weill Cornell Medical Center, said that although physicians have long known that a leaking aortic valve will lead to the formation of scar tissue in the heart muscle, their knowledge has been incomplete as to what causes this scarring and what might be done about it.

It had been thought, for example, that as the valve leaks and allows blood to enter the heart, scarring occurs as a secondary effect of the changes in other parts of heart. The new study shows, instead, that the scar tissue results directly from the stretching of the scar-forming cells of the heart that occurs as large volumes of blood enter the organ through the leaking valve.

The study also identifies several of the genes responsible for this abnormal scar formation.

In addition, the study shows that when the aortic valve leaks, the resulting scar tissue is unusually rich in certain proteins that prevent a normal pumping of the heart. This can lead to heart failure.

Scars are formed when the heart accumulates an abnormal amount of the material that it produces as a scaffolding on which new muscle cells are arranged. To prevent scar formation, new drugs may be created, and the study identifies some of the specific chemical reactions in heart cells which can be targeted by the new drugs. Dr. Borer adds that evaluation of these same chemical reactions may be useful in determining the need for valve surgery in asymptomatic patients.

"The implications of these results are not limited to leaking heart valves," Dr. Borer said. "The same mechanical strains that cause scarring when heart valves leak are present in the hearts of patients who suffer heart attacks, and are likely to be important causes of heart failure in these patients, too. Application of the knowledge gained from this study may ultimately be useful in devising treatments to prevent many causes of heart failure."

Dr. Borer is also a Professor of Cardiovascular Medicine and Cardiothoracic Surgery, a Professor of Medicine, and a Professor of Cardiovascular Medicine and Radiology at Weill Cornell.