Background
Percutaneous mitral valve repair (MVR) is used to treat mitral regurgitation (see the image below). Percutaneous procedures used to treat valvular heart disease were first developed decades ago; the first pulmonic balloon valvuloplasty was reported in 1982, which was quickly followed by applications to the aortic and mitral valves. [1, 2] Mitral stenosis was the first pathologic condition of a heart valve to be treated both surgically [3] and percutaneously. [4]
Percutaneous Mitral Valve Repair. Mitral regurgitation.
Over the past 20 years, percutaneous mitral balloon valvuloplasty used to treat mitral stenosis has yielded excellent success rates in patients with suitable valvular and subvalvular morphology. [5] However, clinically viable percutaneous treatments for mitral regurgitation have become available only relatively recently.
Newer approaches have progressed far beyond balloon valvuloplasty to include catheter techniques for emulating surgical annuloplasty and edge-to-edge repair of regurgitant mitral valves.
A multinational study by Nickenig et al of transcatheter MVR in 628 patients in Europe found that such treatment had a high acute procedural success rate (95.4%) and that reduction in the severity of mitral regurgitation persisted at 1 year. [6] The study also determined that the acute procedural success rate was similar between patients with functional mitral regurgitation and those with degenerative mitral regurgitation, as were the in-hospital (2.9%) and estimated 1-year mortality (15.3%). However, the patients with functional mitral regurgitation had a significantly higher estimated 1-year rate of heart failure-related rehospitalization than did the other group (25.8% versus 12.0%, respectively). [6]
In a study of the initial US commercial experience with transcatheter MVR using the MitraClip, Sorajja et al analyzed data from the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry on patients commercially treated with the MitraClip (N = 564). [7] Procedural success was achieved in 90.6% of patients, and the majority of patients were discharged home with a moderate or lesser degree of mitral regurgitation. The results support the effectiveness of MitraClip therapy in the treatment of appropriately selected, high-risk patients in a commercial setting. [7]
In a prospective, observational study, Scandura et al compared 1-year outcomes of MitraClip therapy in high surgical risk patients with moderate-to-severe or severe mitral regurgitation between patients aged up to 75 versus those 75 years or older (total N: 180 patients) and found that the primary efficacy endpoint occurred in 41 patients, with similar rates between groups. [8] The groups showed no significant differences in cumulative mortality or in the rates of rehospitalization for acute heart failure within 1 year after the MitraClip procedure. Relative to baseline, both groups showed a significant reduction in severity of mitral regurgitation achieved after the procedure at 1-year follow-up and a significant improvement in New York Heart Association (NYHA) functional class. [8]
The COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation) trial randomized 614 patients with heart failure with moderate-to-severe or severe secondary mitral regurgitation and symptoms despite maximally tolerated medical therapy to transcatheter MVR (with MitraClip) plus medical therapy versus medical therapy alone. Transcatheter MVR was safe; provided a durable reduction in mitral regurgitation+, heart failure hospitalizations (51%) and mortality (33%); and improved quality of life and functional capacity compared with medical therapy alone through 36 months. [9]
In the near term, percutaneous valve intervention will probably have several indications, as follows:
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Severe disease deemed inoperable or at high risk of surgical complications owing to comorbid disease
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Treatment of secondary mitral regurgitation in patients with severe symptomatic heart failure refractory to medical therapy
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Early-stage regurgitant lesions if less-invasive valve repair may prevent progressive ventricular enlargement
Various percutaneous approaches are being evaluated and used. The field will develop rapidly over the next several years, with refinement of the above approaches, emergence of still newer technologies, and better identification of which patients are most likely to derive benefit.
If these percutaneous techniques are to be considered as alternatives to traditional surgical methodologies in low-risk to medium-risk patients, they must demonstrate hemodynamic effects, safety, and durability comparable to those of the current highly refined surgical techniques. Conversely, these percutaneous techniques may be best applied to patients at the margins of current surgical indications.
See also Percutaneous Valve Therapies for more information.
Relevant anatomy
The human heart has four valves. The left atrium (LA) is connected to the left ventricle (LV) via the mitral valve, which opens during diastole to allow blood to flow from the LA to the LV. During ventricular systole, the mitral valve closes and prevents backflow to the LA. The normal function of the mitral valve depends on its six components, which include the LA wall, the annulus, the leaflets, the chordae tendineae, the papillary muscles, and the LV wall.
For more information about the relevant anatomy, see Mitral Valve Anatomy and Cardiovascular System Anatomy.
Indications
Despite the general enthusiasm generated by emerging percutaneous devices, establishing which patient populations are suitable for such technologies is important. Degenerative (primary) and functional (secondary) etiologies are two causes of mitral regurgitation most amenable to surgical repair.
Surgical annuloplasty is the main invasive technique for treating functional mitral regurgitation, whereas leaflet repair is also usually performed to treat degenerative mitral regurgitation.
The excellent results and low perioperative mortality associated with surgical repair in selected patients emphasize the need for a thoughtful approach to percutaneous mitral valve repair.
For more details, see the Percutaneous Mitral Valve Repair section in the Percutaneous Valve Therapies topic.
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Percutaneous Mitral Valve Repair. Mitral regurgitation.
