Percutaneous approaches to mitral regurgitation.

Percutaneous therapy for mitral repair has emerged over the past several years as an investigational option for treating mitral regurgitation (MR). A variety of novel methods to treat MR using a percutaneous route have been developed. Most of these approaches are modifications of surgical techniques, some established and some obscure. The basic surgical approaches to mitral repair are annuloplasty and leaflet repair. Catheter-based devices mimic or approximate these surgical approaches. MR as a disease process is heterogeneous, and different therapeutic approaches are needed for different etiologies of MR and morphologies of the mitral apparatus. Primary leaflet diseases are mitral prolapse and fibroelastic deficiency. Secondary, or functional, MR exists when the leaflets are normal. Functional ischemic MR and functional MR related to heart failure occur in different populations and historically have had different responses to surgical therapy. Leaflet repair using a percutaneous clip has been accomplished for patients with mitral valve prolapse and also some patients with functional MR. Indirect annuloplasty via the coronary sinus has shown promising early human trial results in patients with functional MR. Direct annuloplasty and left ventricular chamber remodeling technologies are in the earliest stages of human application. This group of approaches is being studied as an alternative to surgery for selected patients. The MitraClip (Evalve, Menlo Park, CA) for leaflet repair has been approved for use in Europe and is being applied predominantly to high-risk surgical patients with either functional or degenerative, organic MR. One of the coronary sinus devices has received approval in Europe as well. This complex clinical landscape has made device development, trial design, and patient selection complicated. Steady progress in the field is being made. Many patients with functional MR who are currently treated medically will be the subject of upcoming trials. Catheter methods for mitral repair promise to serve some patients currently considered high risk for surgery, and some patients may have catheter therapy as an alternative to surgery.