One more option in heart failure: correction of mitral regurgitation with MitraClip^®

Degenerative mitral regurgitation in elderly patients and functional mitral regurgitation secondary to severe left ventricular dysfunction are not easy options for conventional surgery. Recently, a new percutaneous approach has been proposed with the MitraClip^®, based on the Alfieri edge-to-edge repair technique. The aim of the study is to report, compare and discuss the results of two multicenter randomized trials: MITRA.FR and COAPT in light of the current practice. In both trials patients with functional mitral regurgitation grade 3/4+ or 4/4+ were randomly assigned, in 1:1 ratio, to undergo percutaneous repair and optimal medical therapy or optimal medical therapy alone. Other baseline characteristics reflecting severity of mitral regurgitation and of left ventricular impairment were statistically different, such as the effective regurgitant orifice area (0.31 cm² in MITRA.FR vs 0.41 cm² in COAPT) and the indexed LVEDV (135 ± 37 ml/m² in MITRA.FR vs 101 ± 34 ml/m² in COAPT). A 24 months follow-up and a 12 months follow-up have been completed, respectively, in COAPT and MITRA.FR. Out of the 307 patients enrolled in the MITRA.FR, 152 were randomized to percutaneous treatment but only in 138 (95.8%) the MitraClip^® was actually implanted. At the end of the follow-up a residual mitral regurgitation of at least grade 3+ has been observed in 17% of the patients. A composite of death from any cause or unplanned hospitalizations for heart failure at 12 months respectively occurred in 83 patients (54.6%) treated percutaneously and 78 patients (51.3%) treated with medical therapy only. A total of 614 patients have been enrolled in the COAPT and 293 underwent transcatheter treatment. A successful implantation of the MitraClip^® was achieved in 287 patients (98.0%). Hospitalization for heart failure at 24 months occurred in 160 patients in the device group and in 283 in the control group, with an annualized ratio of 35.8% and 67.9%, respectively (p > 0.001). The conflicting results of the two trials may have many explanations, but probably the main cause is the most stringent inclusion criteria in COAPT. The effective reduction of mitral regurgitation and improvement in exercise capacity already observed in registries including more than 70,000 patients was confirmed in a randomized trial with improvement observed in hard end-points. This has already led to an extension of FDA approval to functional regurgitation and a more liberal use across the world.