Study looks at mitral valve prolapse

Dec 1 2008

Disturbing evidence of higher mortality and lower surgery rates in women versus men with mitral valve prolapse and severe leakage may be related to the complexity of evaluating the condition's severity in women, according to findings of a Mayo Clinic study published this month in the Annals of Internal Medicine.

Mitral valve prolapse affects approximately 150 million people worldwide and often requires cardiac surgery, preferably valve repair rather than replacement, to restore life expectancy of patients with severe leakage, says senior author Maurice Enriquez-Sarano, M.D., a cardiologist at Mayo Clinic. Cardiac valves allow the heart to move blood forward without leakage. Mitral valve prolapse occurs when the leaflets and supporting cords of the mitral valve have excessive tissue and weaken, leading to leakage (regurgitation), he says.

Previous studies on mitral valve disease have examined several sex-based differences, discovering, for example, that mitral valve prolapse is more common in women than men, and that more men than women undergo mitral valve surgery.

This retrospective study examined more than 8,000 patients (4,461 women and 3,768 men) - all patients at Mayo Clinic diagnosed by echocardiography with mitral valve prolapse over 10 years (1989 to 1998).

"This study is significant because it allowed us to look at a large group of patients affected by mitral valve prolapse and examine subtle sex-specific differences that may have been overlooked in the past," Dr. Enriquez-Sarano says. "This study may help physicians manage mitral valve prolapse in women better, more precisely identify women with mitral valve prolapse and severe regurgitation, and treat them - possibly with surgery, which can be lifesaving."

Disturbing differences were observed in men and women with moderate or severe regurgitation - when the mitral valve doesn't close tightly and leaks, with blood flowing backward into the left atrium. The study found that one of the most powerful known reasons to recommend surgery - left ventricular size - was poorly estimated in women because their cardiac size appeared smaller than men, but when their smaller body size was taken into account, cardiac enlargement (a measure of the severity of overload due to regurgitation) was at least as serious, Dr. Enriquez-Sarano says.

Such underestimation of cardiac enlargement may have been the main reason that women with moderate or severe regurgitation were less likely than men to undergo mitral valve surgery. Importantly, this underestimation may have consequences on survival after diagnosis, he says.

In the 15 years following diagnosis, survival rates among women with mitral valve prolapse and no regurgitation were better than men, but odds of survival were worse for women with severe regurgitation, compared with men.

"Physicians who have female patients with mitral valve prolapse and moderate or severe regurgitation must be vigilant. We must consider body size, quantify the leakage as much as possible, and carefully consider valve repair when the regurgitation is severe, so that women, like men, can similarly be offered surgery and its excellent long-term benefit," Dr. Enriquez-Sarano says.