Some seemingly healthy people with high blood pressure suffer from a "silent" heart disease - a finding that may help solve a mystery that has puzzled doctors for years, researchers reported Friday.

Physicians have been stumped why long-term control of hypertension helps prevent stroke or kidney failure - but apparently fails to reduce the increased heart attack risk."Now it looks like some of these people already had silent heart disease before blood pressure treatment was started," said Dr. Julio Tubau, a University of California, San Francisco, assistant professor of medicine. Using sensitive tests to detect inadequate blood flow in coronary arteries, Taubau's research team found symptoms of disease in the heart vessels in four of 48 patients with mild or moderate hypertension.