WEDNESDAY, March 2, 2005 (HealthDay News) -- Improper closure of the heart's mitral valve can spell big trouble for people with the condition, even though some individuals may not show symptoms.
In those cases, the question of whether surgery is required just got a little bit easier, thanks to a study in the March 3 issue of the New England Journal of Medicine.
The study suggests that doctors can make the decision to surgically treat mitral valve regurgitation -- where blood flows back into the heart's atrium -- by simply measuring the size of the abnormal valvular opening.
"Patients should be aware that severe mitral valve regurgitation increases their risk of dying even if they don't have symptoms, and that now we have a measurement technique to determine how severe is too severe and who benefits most from early intervention," said Dr. Maurice Enriquez-Sarano, director of the Mayo Clinic's valvular heart disease clinic, who led the study.
The mitral valve controls the flow of blood from the left atrium of the heart to the left ventricle, the chamber that pumps blood out to the body. If the mitral valve does not close properly, some blood flows back into the atrium. This regurgitation eventually causes an unhealthy enlargement of the atrium. Surgery becomes necessary when symptoms such as fatigue, lightheadedness and shortness of breath appear, but many people can walk around with a malfunctioning heart valve with no evident symptoms.
The Mayo Clinic team tracked the outcomes of 456 such people for five years, getting detailed ultrasound images of their hearts and recording other factors that could influence their health. Three factors stood out -- age, presence of diabetes, and the size of the opening allowing blood to flow back into the atrium.
People with an opening greater than 40 square millimeters had a staggeringly poor outcome, the study found. Their risk of dying in the next five years was nearly three times greater than those given drug treatment, their risk of death from heart conditions was more than five times greater and their risk of a heart attack or other cardiac crisis was also more than five times greater.
Those excess risks vanished when surgery was done to repair the mitral valve, said Enriquez-Sarano.
"The people we operated on did extremely well," Enriquez-Sarano said. "People who are operated on despite having no symptoms have an excellent long-term outcome. Essentially, we can restore the normal life span."
Cardiologists have long known that surgery is needed for mitral valve regurgitation, but there has been uncertainty about when to operate, he said. American Heart Association guidelines recommend surgery when symptoms appear or when there are signs of poor left ventricle function.
"This study now provides us with a group that we have identified as being of high risk and for whom we can consider for surgery," Enriquez-Serano said.
Mitral valve regurgitation is a problem that is affecting more and more Americans as the population ages, since its incidence increases with age. According to the American Heart Association, at least 2 million Americans now have the problem, and the number is predicted to rise to at least 3.8 million by 2030.
The study results "confirm what many of us clinicians have suspected for a long time, that someone with mitral valve regurgitation should be operated on sooner rather than later," said Dr. Curt M. Rimmerman, a staff cardiologist at the Cleveland Clinic.
He said the results probably will affect the way he practices, since he treats many patients with mitral valve problems.
"In our institution, we often have followed asymptomatic patients, giving a stress echocardiogram once a year and educating them about symptoms," he said. "This paper would suggest that we should be operating sooner."
Mitral valve problems and how they are treated are described by the Society of Thoracic Surgeons .