Treating Mitral Valve Disease Sooner May Improve Outcomes

By Marilynn Larkin, Reuters Health
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NEW YORK (Reuters Health) - Many patients with mitral valve disease are referred too late and receive treatment only after heart or lung damage has occurred, researchers say.

"I hope the results of the study will continue to raise awareness of the presence of mitral valve disease and of the importance of early referral for evaluation by a heart team," Dr. James Gammie of University of Maryland School of Medicine in Baltimore said in an email to Reuters Health.

Dr. Gammie and colleagues studied 87,214 patients at 1,125 centers in North America who underwent isolated primary mitral valve operations with or without tricuspid valve repair, atrial fibrillation ablation or atrial septal defect closure between 2011 and 2016. The mean age at surgery was 64, and about half were women.

Atrioventricular valve. (Source: National Institutes of Health)

As reported online July 19 in Annals of Thoracic Surgery, the number of mitral valve operations increased by 24% annually during the study period, from 14,442 in 2011 to 17,907 in 2016. The overall repair rate was 65.5%; the replacement rate was 34.4%.

The most common mitral valve disease etiology was degenerative leaflet prolapse (DLP; 60.7%); 4.3% of patients had functional mitral regurgitation. Other etiologies included rheumatic disease, endocarditis, pure annular dilation and various uncommon diseases. Preoperatively, 47.3% of patients had an ejection fraction less than 60% and 34.2% had atrial fibrillation.

Repair rates declined from 67.1% in 2011 to 63.2% in 2016, and were related to etiology - i.e., 82.7% for DLP; 17.5% for rheumatic disease. Rates varied for other, significantly less prevalent conditions, such as endocarditis and nonischemic cardiomyopathy.

Repair techniques included prosthetic annuloplasty in 94.3% of cases, leaflet resection (46.5%), and artificial cord implantation (22.7%).

Replacement with bioprosthetic valves increased during the study period, from 65.4% in 2011 to 75.8% in 2016. Less-invasive operations were performed in 23% of cases, with concomitant tricuspid valve repair in 15.7%.

Unadjusted operative mortality was 3.7% for replacements and 1.1% for repairs.

The authors note that mitral valve operations are the fastest growing surgical intervention captured in the Society of Thoracic Surgeons Adult Cardiac Surgery Database. Still, aortic valve operations were performed 1.6 times more often than mitral valve operations during the study period, although the prevalence of mitral valve disease is twofold to threefold higher.

"That may suggest important underreferral and undertreatment of mitral valve disease, which may be related to the slower progression of signs and symptoms of mitral compared to aortic disease, as well as a potential lack of adherence to guidelines for intervention," they state.

"Earlier guideline-directed referral and increased frequency and quality of repair may further improve results of mitral valve operations," they conclude.

"A significant proportion of patients were referred for operation after some degree of damage to either their heart or the blood vessels in the lungs had occurred," Dr. Gammie noted. "This may have resulted from patients presenting to a physician late, or perhaps from late referrals to surgeons from either primary care physicians or cardiologists."

Dr. Mathew Williams, director of the Heart Valve Center at NYU Langone Health in New York City, told Reuters Health, "We've known for a long time that patients need to be referred earlier and we have witnessed the survival advantages with earlier referral. Despite this information, the study highlights that practice is not changing and suggests that referring physicians are unwilling to alter their practice."

"Admittedly, many physicians struggle with referring patients for surgery who have no symptoms," he said by email. "In order to optimize treatment benefits, asymptomatic patients need to be treated before experiencing negative side effects of the disease."

"Think about it as it relates to cancer," he said. "You would hardly leave cancer to grow and further disrupt the patient (before removing) the disease. Unfortunately, this is what physicians are doing by waiting to send patients for (mitral valve) surgery."

"Hopefully, as we develop and expand upon less invasive techniques for treatment, particularly those that can be done with catheters, we will be able to treat more patients earlier," he said.

"Those responsible for writing guidelines need to be more aggressive," he added.


Ann Thorac Surg 2018.

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