Such people are five times more likely to die of a heart problem or develop heart failure or an irregular heartbeat than those with mild leakage, researchers at the Mayo Clinic reported in Thursday's New England Journal of Medicine (news - web sites).
Their study involved the mitral valve, which connects the upper left chamber with the heart's main pumping chamber. If the valve's two flaps don't close tightly, blood can leak back into the upper chamber when the heart contracts.
Most people don't feel anything, but if it gets gets worse, they can develop shortness of breath, fatigue, dizziness and palpitations.
Doctors can detect the condition by listening to the heart, but usually don't recommend surgery to repair or replace the valve unless it causes symptoms or damages the heart itself.
The Mayo researchers used a relatively new ultrasound technique to take measurements of the hearts of 456 patients who had leaky valves but no symptoms and found that the size of the hole in the valve was the strongest predictor of how the patient would fare. Without surgery, those with bigger holes — about the width of a pencil — did the worst.
"When it's severe, it's fixable. And we can determine when it's severe now with new techniques," said Dr. Maurice Enriquez-Sarano, who led the study.
Of the estimated 2.7 million Americans with notable leakage, about 600,000 are probably candidates for early surgery, Sarano said.
Study participants were enrolled between 1991 and 2000. All had leaky heart valves without symptoms and no other heart problems. Their disorder was classified mild, moderate or severe based on the volume of their leakage and the size of the valve hole.
Participants were monitored and treated independently by their own physicians, and updated information on the patients was collected by the researchers in 2002.
Their findings showed age, diabetes and the valve hole were strong predictors of survival.
Eventually, 232 had heart surgery, all but two for valve repair or replacement. The researchers said surgery reduced the patients' risk of heart failure and death and their life expectancy returned to normal.
Dr. Catherine Otto of the University of Washington in Seattle, said the study is a big step forward because physicians can use the measurement to tell patients what to expect if they have a valve problem. But she said the measurements are challenging to make, and the data apply only to those without any other heart problem.
"I don't want every patient to rush off and demand surgery tomorrow," said Otto, co-author of an accompanying editorial in the journal. "Some people will go to surgery earlier if their surgery risk is low and their valve is repairable."
The editorial writers and Sarano said the next step is a randomized study in severe cases that compares early surgery with surgery done when symptoms appear.
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New England Journal: http://www.nejm.org
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