Management of Mitral Regurgitation: Indications for Surgery

Points to remember

• Mitral valve regurgitation (MR) affects more than 2 million people in the United States.
• Mitral valve regurgitation can progress in severity to a serious condition associated with excess mortality and morbidity.
• Doppler echocardiography is the main assessment tool for delineating the anatomic cause of MR and quantifying its severity.
• Surgery for severe MR, preferably valve repair, improves a patient's outcome particularly when it is done before symptom onset, marked dilation of the left heart dimension, or a decrease in ejection fraction.

The challenge

The management of mitral valve regurgitation (MR) has evolved greatly during the past 2 decades. Considerable progress has been made toward earlier diagnosis of MR to precisely quantify the severity of MR and to define clearly the cause of the MR and the prospects for valve repair in patients with severe MR.

Recent research established the long-term benefits of performing valve repair before symptom onset and underscored the importance of proactive management and early surgical intervention. The risk of surgery, although very low, is a concern that leads to careful evaluation of the risk and benefit in each person affected by MR.

Schematics of organic MR and mitral valve repair

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Schematics of organic MR and mitral valve repair

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Schematics of organic MR and mitral valve repair

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Schematics of organic MR and mitral valve repair

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An evolving approach

Multiple studies from Mayo Clinic and other institutions have demonstrated the considerable decrease in operative risk recently and the excellent outcome of surgery performed early.

An objective guideline for an early surgical decision was established by a Mayo Clinic study of 456 patients who had MR but were without severe symptoms when MR was diagnosed. Five years after enrolling in this prospective study, patients with an effective regurgitant orifice (ERO) larger than 40 mm2 who were treated only with medication had a notable risk of cardiac events and death. In those with the same severity of MR who underwent early valve repair, the risk of death or cardiac events was considerably reduced and life expectancy was restored.

Since then other studies from Europe and Asia confirmed the Mayo Clinic study's findings and also showed considerable benefit with early surgery involving valve repair.

Mayo Clinic's approach to treating MR emphasizes proactive assessment and management. Detailed longitudinal studies and improved techniques of 2-dimensional and Doppler echocardiography have allowed the identification of evidence-based markers for recommending mitral valve surgery in patients with severe MR. Accurate echocardiographic delineation of both the anatomic cause and the severity of MR allows selection of an optimal treatment strategy based on well-defined outcomes.

Given the benefits associated with early surgical correction, Mayo cardiologists now recommend prompt surgical evaluation for patients with classic indications (symptoms or ventricular failure) and asymptomatic patients with MR and:

• Left ventricular end-systolic dimension between 35 and 40 mm
• ERO e40 mm2
• Cardiac hormonal activation
• Markedly reduced functional capacity
• Atrial fibrillation (even paroxysmal)

Surgical repair vs replacement

The long-term durability of primary and reoperative valve repair has been clearly established. At medical centers like Mayo Clinic, where surgeons perform large numbers of valve procedures on a regular basis, mitral valve repair offers several advantages over valve replacement. Successful valve repair allows patients who maintain sinus rhythm to resume full activities without the need for chronic anticoagulation.

3-D view of mitral valve

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Although the durability of mitral valve repair and replacement are similar, survival rates associated with valve repair are superior to those associated with prosthetic replacement. While patients who undergo valve replacement with a biological prosthesis usually do not require anticoagulation, their long-term need for reoperation is much higher than that of patients undergoing valve repair. Also, valve replacement with a mechanical prosthesis entails a risk of stroke that persists over the years and requires anticoagulation for life, with a notable risk of bleeding. Therefore, valve repair is the preferred method of surgical correction for patients with severe MR. This option is the key to considering surgery before the appearance of symptoms.

Mitral valve repair, performed classically by opening of the chest or through newer minimally invasive surgery, provides durability and restores life expectancy with minimal risk of morbidity. Such progress has transformed the long-term outlook of patients with severe MR.