Uncovering Gender Differences in Mitral Valve Surgery

February 23, 2015

A study of gender differences in mitral valve surgery has generated interest in the professional community because it sheds light on an aspect of valve surgery that hasn’t been well-studied to date.

“We know from the medical literature that women typically are referred for diagnostic tests and, therefore, surgery, later than men, partly because of atypical symptoms,” said the study’s principal investigator, Vincent Chan, MD, cardiac surgeon at the University of Ottawa Heart Institute. “We don’t know if this is the case for valve surgery as well.”

Mitral valve surgery is performed to correct mitral valve regurgitation, which occurs when the valve doesn’t close tightly. The result is that blood flows backward into the heart and can’t move as efficiently through the body as it should. This can result in fatigue and shortness of breath.

Thanks to Dr. Chan’s study, we now know a little more about gender differences in this surgery. For instance, we know that women generally have more advanced disease in their mitral valves than do men when they are referred for surgery, experiencing greater prolapse (misalignment) of the mitral leaflets and greater calcification at the opening of the valve. Women also undergo valve replacement, rather than repair, more often than men.

We have also learned that this more advanced disease doesn’t have an impact on survival—both women and men have similar survival rates, close to 90 per cent, five years after surgery. Women, however, experience recurrent mitral regurgitation after surgery slightly more often than men.

Since the experience of mitral regurgitation was the clinical end point of the study, Dr. Chan indicated that the long-term impact of a greater recurrence of mitral regurgitation isn’t apparent yet.

Dr. Chan presented his study to the Canadian Cardiovascular Conference in October 2014, and more recently, he was asked to present it at the annual meeting of the Society of Thoracic Surgeons, held in January. At that international event, it was selected as one of the top three presentations.

The sheer number of mitral valve surgeries performed at the Heart Institute made it possible for Dr. Chan to carry out his study entirely at the institute. The median annual number of these procedures performed at centres in the United States is just five versus 57 at the Heart Institute. The study included 743 surgeries conducted between 2001 and 2014.

All these surgeries were performed by Dr. Chan or by Thierry Mesana, MD, PhD, now President and CEO of the Heart Institute and one of the world’s leading mitral valve surgeons. A database set up by Dr. Mesana to track these patients—one of the only such databases dedicated solely to mitral valve surgery—allowed Dr. Chan to follow these patients and to assess their continuing heart health. The average follow-up period was nearly three years, with the longest being more than 11 years. The database provided access to all care and testing, including records of subsequent echocardiograms, undertaken to examine valve function.

“Complex mitral valve reconstruction has unique parameters,” said Dr. Chan. “Having this data makes possible unique insights.”