"We know from previous studies that patients with symptomatic mitral regurgitation are at increased risk of death, but for those without symptoms the picture has been murkier," says Maurice Enriquez-Sarano, M.D., the Mayo Clinic cardiologist who led the study. "In this study we followed a large population of asymptomatic patients prospectively to identify keys to improved long-term outcomes, and to determine when patients should consider surgery."

The mitral valve separates the left upper chamber of the heart (atrium) from the left lower chamber (ventricle). In mitral regurgitation this valve does not close properly, which causes some blood to backwash into the heart from the left ventricle instead of being pumped out to the rest of the body. The left atrium typically enlarges due to this pressure, and as a result of this compensation the patient may not experience symptoms initially. As the disease progresses, symptoms may include fatigue, exhaustion, light-headedness, shortness of breath and heart palpitations.

Mitral regurgitation of moderate degree or more is frequent, particularly in the aging population. It is estimated that 2 to 2.7 million Americans are afflicted by this condition and that this number will rise to 3.8 to 4.8 million Americans by 2030.

The Mayo Clinic researchers used Doppler echocardiography ultrasound images of the heart and its blood flow patterns to determine which physical characteristics predicted patient outcomes. Age and diabetic status were strongly associated with poorer outcomes. However, the most important finding was that the effective regurgitant orifice area the cross-sectional size of the jet stream of blood backwashing into the atrium was the strongest determinant of outcome.

Patients with a regurgitant orifice larger than 40 mm2 who were treated only with medication were more than five times more likely to die than those with the same severity of regurgitation who underwent valve repair s
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Contact: Lee Aase
newsbureau@mayo.edu
507-284-5005
Mayo Clinic
2-Mar-2005

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