経皮的僧帽弁修復術の可能性

Preliminary results from studies such as EVOLUTION suggest that percutaneous mitral repair may be beneficial and safe for selected patients with mitral regurgitation who are not currently being treated surgically, according to a presentation at the annual meeting of the European Society of Cardiology.

Based on EuroHeart Survey results, mitral regurgitation represents the second most important native valve disease in Europe (30 percent). The same survey suggests that mitral valve repair is performed only 50 percent of the time. This shortfall is mostly due to a lack of expertise in performing the procedure. Finally, survey data highlight the fact that half of the patients, despite the presence of severe symptoms and severe mitral regurgitation, are not considered for surgery by their physicians. Thus, there is a need for treatment other than surgery for high-risk patients or those denied surgery.

Percutaneous mitral valve repair was introduced only a few years ago. There are two different approaches to percutaneous mitral valve repair.

The first approach is the edge-to-edge technique, which creates a double mitral valve orifice replicating the surgical intervention pioneered by Professor Alfieri. This technique is very demanding because it requires trans-septal catheterization and sophisticated collaboration between the echocardiographist and interventionist to catch the valve at the appropriate moment and location.

Preliminary clinical results obtained in over 100 patients suggest that in expert hands the feasibility of the technique is high (80-90 percent) and the degree of mitral regurgitation can be reduced to mild in two thirds of cases. In addition, the risk is low, once again, in experienced centers. In patients where the procedure was successful, two thirds remained event free after three years. Thus these data, even if only preliminary, are encouraging.

The second possible approach is mitral annuloplasty, which is achieved by introducing a constraining device in the coronary sinus located in the vicinity of the mitral annulus. The rationale here is that ring annuloplasty is almost always combined with other procedures during surgical interventions on the mitral valve. More than ten devices have been designed and three are currently being studied. They share common technical features: distal fixation and proximal fixation in the coronary sinus and a bridge between the two fixating elements.

Annuloplasty is easier because it only requires catheterization of the coronary sinus. Preliminary results from the EVOLUTION study in 60 patients show high feasibility (90 percent) and good safety profiles: Almost 80 percent of patients experienced no complications within 90 days. Very preliminary efficacy data suggest a reduction in the degree of regurgitation.

Clearly at the present stage these two approaches do not yet reach the standard of the multiple surgical techniques that make the success of surgical mitral valve repair.
The annuloplasty technique could be potentially used in patients with functional mitral regurgitation, while the edge-to-edge technique could be used in selected patients with degenerative mitral regurgitation. The potential clinical indications of the new percutaneous techniques are represented by the vast group of patients with contraindications or judged to be at very high risk for surgery.

Many devices are currently being studied or are at the experimental stage: suture-based direct annuloplasty, percutaneous mitral valve replacement, or transpericardial left ventricular remodeling.

Further research should be carefully evaluated in comparison with surgery and standard contemporary medical treatment including cardiac resynchronization. Trials such as EVEREST II, EVOLUTION II, and AMADEUS are underway.

Development of such new techniques will require close collaboration between engineers, interventionalists, imaging specialists, and surgeons.