Percutaneous mitral valve edge-to-edge repair with the Evalve MitraClipTM System: rationale and phase I results

Introduction Mitral regurgitation (MR) is associated with an increase in mortality in patients with left ventricular dysfunction1, and more recently has also been associated with increased cardiac events even in asymptomatic patients2. The combination of a desire to improve survival as well as quality of life in symptomatic subjects accounts for the approximately 100,000 mitral valve operations performed worldwide annually. About half of these operations are mitral valve replacements, which can provide excellent reduction in mitral regurgitation and can be performed more quickly and by surgeons with less training than is necessary for mitral valve repair surgery. However, bioprostheses have limited longevity and mechanical valves require lifetime anticoagulation, which may limit their benefit. The potential for mitral valve repair to better maintain ventricular function and thereby improve patient survival has led to a recent increase in repair operations when the anatomy is suitable3. Despite the reported advantages of mitral valve repair, no randomized trial has been conducted to compare repair with valve replacement. Observational studies that report the benefit of mitral valve repair often utilize the endpoint of freedom from re-operation rather than survival and report actual repairs as opposed to intention to treat. The latest generation of bioprostheses have demonstrated a marked improvement in valve longevity, and the use of chordal sparing may further improve the results of replacement. Both types of surgery are associated with significant morbidity in addition to mortality, which may be as high as 20%. In one study of Medicare patients undergoing mitral valve replacement, readmission within 30 days of surgery occurred in over 20% of patients4. Repair procedures usually involve annuloplasty, and for degenerative valve disease frequently employ leaflet resection. In 1990, Alfieri introduced a novel surgical edge-to-edge repair technique involving the approximation of the middle scallops of the anterior and posterior mitral leaflets5. The results of this approach have been reported both in patients with and without ring annuloplasty with excellent results, even without a ring in patients with a noncalcified annulus6,7. Recently, a percutaneous procedure to create the same type of double orifice mitral valve was developed, and the results of a phase 1 safety and feasibility trial of this technique (EVEREST I) have been reported9. In this review, we will describe this procedure and report the additional results of the first 47 patients treated.