Transcatheter mitral repair and replacement: state of the art and future directions

Many patients affected by severe mitral regurgitation (MR) do not currently undergo surgery, mainly because of the high surgical risk due to old age, impaired left ventricular function and comorbidities. Consequently, many transcatheter devices are emerging with the purpose of treating MR in a less-invasive fashion, using different approaches and addressing different anatomic targets. The most widely used device in the clinical setting at present is the MitraClip system (Abbott Vascular, Inc., Menlo Park, CA, USA), which 'clips' the mitral leaflets together to force coaptation, and has shown optimal safety and acceptable clinical results, despite the high-risk profile of the patients in which it is commonly used. Other repair technologies include percutaneous neochordae implantation, direct and indirect annuloplasty, and reshaping of the left ventricle, but these are still undergoing limited clinical trials or preclinical experience. The combination of different repair techniques is likely to be required to achieve good long-lasting results. Transcatheter mitral valve implantation is also under development, and has already been carried out successfully in the context of valve-in-valve, whereas in the native scenario it remains an open challenge because of the particular anatomic and physiologic features of the mitral complex; hence, various prostheses using different concepts are emerging, and the first human cases have already been treated. Because data on the safety, efficacy and durability of all transcatheter mitral therapies are still limited, they are currently reserved to high-risk and inoperable patients, and their application requires an integrated Heart-Team approach. However, they represent the natural evolution of surgery and promise to expand treatment options and improve patient outcomes in the near future.