Impact of procedural success on clinical outcome after MitraClip: Results from the MITRA-FR trial

Background: Differences in procedural success rates have been proposed to explain the divergent results between the MITRA-FR trial (Percutaneous Repair with the MitraClip Device for Severe Functional/Secondary Mitral Regurgitation) and the COAPT trial (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation).

Aim: To examine whether MITRA-FR patients who had successful clip implantation achieved a better outcome than the control group.

Methods: Based on the per protocol population of MITRA-FR, we compared the outcome in 71 patients in whom optimal clip implantation was achieved (group 1: mitral regurgitation grade ≤ 1 + at discharge) with that in 23 patients with non-optimal clip implantation (group 2: mitral regurgitation grade ≥ 2 + at discharge) and that in 137 patients in the control group (group 3). The primary endpoint was all-cause death or unplanned hospitalization for heart failure at 24 months.

Results: Event-free survival was not different across the groups (42±6% in group 1, 30±10% in group 2 and 31±4% in group 3; log-rank P=0.32). In multivariable analyses, after adjustment for age, sex, rhythm, aetiology, left ventricular ejection fraction and mitral regurgitation severity, group was not associated with variations in outcome: using Group 3 as reference, hazard ratio 0.86, 95% confidence interval 0.58-1.27 (P=0.43) in group 1; and hazard ratio 0.98 95% confidence interval 0.54-1.76 (P=0.94) in group 2.

Conclusions: The clinical outcome of patients in whom optimal procedural result was achieved at discharge was not different compared with the control group. Our results do not support the hypothesis that the differences in rates of residual mitral regurgitation at discharge between MITRA-FR and COAPT explain the divergent results between the two trials.