"Patients with mitral regurgitation who develop atrial fibrillation have a problem that should be addressed promptly," says Maurice Sarano, M.D., 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. Although all of the patients started with normal heart rhythms, almost half developed atrial fibrillation within 10 years and those patients had higher rates of heart failure and cardiac mortality than
patients who maintained normal rhythm. Advancing age and increased left atrial size were the two predictors of rhythm disturbance. The dysrhythmia rate was similar in patients with flail leaflets and also in patients with mitral valve prolapse.

The researchers theorize that the pressure from backflow of blood into the left atrium causes stress that enlarges the chamber and eventually leads to atrial fibrillation.

"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."