Percutaneous transcatheter mitral valve repair: a classification of the technology.
Surgical treatment of mitral regurgitation (MR) has evolved from mitral valve replacement (MVR) to repair (MVR(e)), because MVR(e) produces superior long-term outcomes. In addition, MVR(e) can be achieved through minimally invasive approaches. This desire for less invasive approaches coupled with the fact that a significant proportion of patients–especially elderly persons or those with significant comorbidities or severe left ventricular (LV) dysfunction, are not referred for surgery, has driven the field of percutaneous MVR(e). Various technologies have emerged and are at different stages of investigation. A classification of percutaneous MVR(e) technologies on the basis of functional anatomy is proposed that groups the devices into those targeting the leaflets (percutaneous leaflet plication, percutaneous leaflet coaptation, percutaneous leaflet ablation), the annulus (indirect: coronary sinus approach or an asymmetrical approach; direct: true percutaneous or a hybrid approach), the chordae (percutaneous chordal implantation), or the LV (percutaneous LV remodeling). The percutaneous edge-to-edge repair technology has been shown to be noninferior to open repair in a randomized clinical trial (EVEREST II [Endovascular Valve Edge-to-Edge REpair Study]). Several other technologies employing the concepts of direct and indirect annuloplasty and LV remodeling have achieved first-in-man results. Most likely a combination of these technologies will be required for satisfactory MVR(e). However, MVR(e) is not possible for many patients, and MVR will be required. Surgical MVR is the standard of care in such patients, although percutaneous options are under development.