Perspective:

The following are 10 points to remember about this state-of-the-art paper:

1. Mitral regurgitation (MR) is a common problem and is present in over 7% of patients over the age of 75.

2. Current guidelines recommend surgical intervention for symptomatic severe MR or asymptomatic severe MR with left ventricular (LV) dysfunction or enlargement. Mitral valve repair is favored over replacement for patients with degenerative valve disease.

3. Percutaneous MR repair is increasingly being considered and the techniques have been previously grouped into technologies targeting leaflets, direct annuloplasty, or indirect annuloplasty via the coronary sinus, and LV remodeling.

4. The MitraClip system uses a steerable catheter to deliver a clip to the anterior leaflet and posterior leaflet via transseptal access. The system was evaluated in the EVEREST I (Endovascular Valve Edge-to-Edge REpair Study) trial, and a successful reduction in MR (post-procedure MR <2) was achieved in 74% of patients with an in-hospital mortality of <1%. Over 76% of patients were free from surgery at 3 years.

5. The EVEREST-2 trial randomized 279 patients to surgery versus MitraClip in a noninferiority design. Freedom from combined endpoint of death, MV surgery, or reoperation more than 90 days after the index procedure, and MR >2+ at 1 year was 72.4% in the device arm and 87.8% in the surgery arm.

6. Leaflet ablation using radiofrequency has been explored as a means to induce leaflet fibrosis and shortening. While initial animal studies support proof of concept, lack of controlled change in leaflet morphology, leaflet injury, and perforation are potential concerns. No human data are available at present.

7. Indirect annuloplasty techniques involve implantation of devices within the coronary sinus with the aim of “pushing” the posterior annulus anteriorly, reducing the septal-lateral dimension of the mitral annulus, and improving leaflet coaptation. This approach is utilized by a variety of devices that have undergone phase I and II studies, but concerns about circumflex artery compression and marked variability in the relation of the coronary sinus and mitral annulus limit their widespread applicability.

8. Direct annuloplasty techniques involve strategies to cinch the mitral annulus via the LV or left atrial approach using mechanical devices or focused energy (ultrasound or heat). These strategies are in the early stages of development.

9. The leaflet space occupier concept involves using a device across the mitral annulus against which leaflets can coapt. This strategy is currently being evaluated in phase I trials. Other strategies that are being explored include chordal implantation and device-based LV modeling.

10. Three approaches to percutaneous mitral valve are being explored and involve a transapical, transseptal, or left atrial approach via a mini thoracotomy. Significant challenges include the saddle shape and the variability in the anatomy of the mitral annulus, paravalvular leaks, and LV outflow obstruction from retained valve tissue.