heart surgery

New Therapies for Mitral Valve Disease

Mitral valve disease affects an estimated 4 million adults living in the United States. Common treatments for mitral valve disease include surgical intervention. Andres M. Pineda, MD, an assistant professor in the Department of Medicine, Division of Cardiology, at the University of Florida, Jacksonville, recently spoke about new therapies for mitral valve disease at the Women and Heart Disease Conference. He answered questions about the implications of these new therapies. 

CONSULTANT360: What are the new therapies for mitral valve disease?

Dr Maldonado: The treatment for mitral valve disease depends primarily on the type of valvular lesion (regurgitation or stenosis) and its etiology. Mitral valve replacement is the most common treatment for severe mitral stenosis. Percutaneous mitral valve balloon commissurotomy is preferred for patients with severe symptomatic rheumatic mitral stenosis and favorable mitral valve anatomy. Severe primary mitral valve regurgitation (MR) is treated with valve surgery, which may be accomplished by repair (preferred) or replacement. The type of surgery depends on the patient's anatomy and also on the surgeon’s expertise. A significant proportion of patients with mitral valve disease are not candidates for surgical interventions or are at high risk for surgery-related complications due to advanced age, multiple medical problems, or other factors. Catheter-based therapies for mitral valve disease have been developed in the last decade for these patients.  

The transcatheter mitral valve edge-to-edge repair (MitraClip) was developed for patients with severe primary MR. It significantly reduces MR and improves left ventricular function and remodeling, pulmonary arterial pressures, heart failure symptoms, and survival. Compared with medical therapy alone, MitraClip significantly improves survival in patients at extreme risk for surgery. It also provides similar survival and symptomatic improvement compared with surgery in high-risk patients. Transcatheter mitral valve repair is currently an established therapy for patients with severe primary MR and high or extreme risk for surgery.

More recently, MitraClip was approved for patients with severe secondary (or functional) MR. In this cohort of patients, in which mitral valve surgery has not clearly shown benefit, MitraClip significantly reduced heart failure admission and improved survival compared with guideline-directed medical therapy. It is expected that MitraClip will soon gain approval by the US Food and Drug Administration (FDA) and be included in the guidelines for this indication. 

Transcatheter mitral valve replacement (TMVR) using a balloon-expandable transcatheter heart valve (Sapien) can now be performed for patients with a degenerated surgical mitral valve bioprosthesis (severe regurgitation or stenosis) at high risk for surgery, achieving excellent outcomes. Although not FDA approved, TMVR can also be performed for patients with MR or stenosis related to prior surgical annuloplasty rings or severe mitral annular calcification (MAC).

Several other devices for transcatheter mitral valve repair, including direct and indirect annuloplasty systems, have been developed in past few years and are currently undergoing initial feasibility studies. Similarly, several transcatheter systems for mitral valve replacement are currently under investigation.  

C360: How do these therapies differ for men vs women?

Dr Maldonado: There are significant gender differences for the surgical treatment of mitral valve disease and its outcomes. First, mitral valve surgery through a conventional median sternotomy may be more aesthetically unpleasant for women compared with men. Minimally invasive mitral surgery through a lateral thoracotomy, for example, could be technically challenging in women due to their breast anatomy. Second, women with mitral regurgitation are less often treated with mitral valve repair and more likely to get a replacement compared with men. Mitral valve repair is the preferred surgical treatment, as it is associated with fewer perioperative complications compared with replacement. Finally, but a more important issue, the postoperative outcomes of mitral valve surgery in women are worse compared with men, including longer length of hospital stay and higher short- and long-term mortality. This observation may be due to older age, more advanced disease, or more comorbidities at the time of surgery, or/and the higher rate of valve replacement in women.

On the other hand, several reports have shown there are no gender differences in the clinical outcomes after transcatheter mitral valve repair with the MitraClip system. In fact, one report suggested the 5-year survival after MitraClip is better for women.

C360: How would a cardiologist choose which therapy is appropriate for which patient? What is your method?

Dr Maldonado: The best therapy for each patient is chosen based on the patient’s mitral valve pathology (stenosis vs regurgitation, primary vs secondary regurgitation, etc.), symptoms, and risk for perioperative complications and mortality. In general, symptomatic patients at low risk for surgical-related complications will have open heart surgery, whereas the newer catheter-based therapies are for those with significant symptoms and high risk or who are not candidates for surgery. It should be a shared decision with the patient, and ideally using a team approach in which the interventional cardiologists, cardiac surgeons, and other specialists come up with the ideal treatment plan. This is the method used at my institution and in most academic centers. 

C360: Can you talk about a challenging patient with mitral valve disease? How did you handle that situation?

Dr Maldonado: Nine years ago, a patient with history of a prior mitral valve replacement (bioprosthesis) presented to my institution with severe heart failure symptoms and had very severe prosthetic mitral stenosis. Due to multiple other medical issues, including severe left ventricular dysfunction, the patient was not a candidate for redo mitral valve replacement. After the patient was discussed in our weekly multidisciplinary structural heart and valve meeting, it was decided to treat the patient with a valve-in-valve transcatheter mitral valve replacement, in which a transcatheter heart valve (typically for aortic valve replacement), delivered from the femoral vein and across the atrial septum, is implanted inside the old surgical bioprosthesis. The procedure, which was technically challenging, was completed successfully, and the patient recovered uneventfully.

C360: What other takeaways should cardiologists know about the new therapies for mitral valve disease?

Dr Maldonado: There is a huge number of patients with mitral valve disease out there that are not being treated due to the idea that patients may not get through open heart surgery. So, therefore, I think the main takeaway for family medicine, internal medicine, and cardiovascular specialists is that these newer catheter-based therapies for mitral valve disease are now available and used in daily practice in specialized centers. Additionally, within the next 5 to 10 years, the number of transcatheter options will grow exponentially and patients who may not be suitable candidates now will be in the future.