Mayo Clinic Study Finds Leaky Valve Leads to Common, Risky Heart Rhythm Disturbance

Mayo Clinic doctors have found that a heart rhythm disturbance called atrial fibrillation is common in patients with leaky mitral valves, suggesting that surgical valve repair should be more strongly considered in those patients.

The research findings are published in the July 3, 2002 edition of Journal of the American College of Cardiology.

"Patients with mitral regurgitation who develop atrial fibrillation have a problem that should be addressed promptly," says Maurice Sarano, M.D., a Mayo Clinic cardiologist and senior author of the study. "Our findings suggest that we need to be much more aggressive about getting these patients into surgery."

The study followed 449 patients with mitral regurgitation, a condition in which the valve between the left atrium and the left ventricle does not close properly. The left ventricle is the chamber that pumps blood to the rest of the body, but a leaky mitral valve causes a jet stream of blood to also shoot backward into the left atrium. The researchers theorize that this backward pressure causes stress that enlarges the left atrium and eventually leads to atrial fibrillation, a condition in which the upper chambers of the heart contract irregularly and inefficiently.

Atrial fibrillation is common in the elderly, and is associated with increased risk of stroke, heart failure and early cardiac death.

While all of the patients had started with normal heart rhythms, almost half developed atrial fibrillation within 10 years, and those patients had higher rates of heart failure and cardiac death thanthe ones who maintained normal rhythm. Advancing age and increased left atrial size were the two factors that predicted which patients would go on to develop rhythm disturbances. The rhythm problem was similar in patients with so-called "flail leaflets" and also in those with a less severe form of degenerative mitral valve disease, mitral valve prolapse.

"This study suggests that a patient with mitral regurgitation who has an enlarged left atrium is likely on the way to atrial fibrillation," says Dr. Sarano. "For these patients, surgery to correct the valve problem should be considered. Research into medical therapies to reduce pressure on the atrium must continue, but given the very low risks of surgical repair and the high risks of atrial fibrillation and its negative consequences, this tilts the balance in the direction of the surgical approach. At the very least, these patients should be closely monitored for the onset of atrial fibrillation.

"For patients with degenerative mitral valve disease who are already experiencing atrial fibrillation, the decision is much more clear cut. The valve should be repaired surgically to reduce stress on the atrium and a MAZE procedure, which helps redirect stray electrical impulses in the heart, may be considered to eliminate the atrial fibrillation."