Percutaneous mitral annuloplasty with the Carillon device: outcomes in proportionate and disproportionate functional mitral regurgitation.

BACKGROUND: It has been suggested that the disparity of outcomes between the studies of transcutaneous edge-to-edge repair (TEER) for functional mitral regurgitation (FMR) in heart failure with reduced ejection fraction (HFrEF) could be due to systematic differences in the populations studied. One proposal is that there are two broad groups: those with proportional FMR who respond less favourably, and those in whom the FMR is greater than expected (disproportionate) FMR where edge-to-edge TEER seems to be more effective. Whether this grouping is relevant for other percutaneous interventions for FMR is unknown.

OBJECTIVES: We sought to compare clinical and echocardiographic outcomes of patients with HFrEF and proportionate and disproportionate FMR treated with indirect annuloplasty using the Carillon device.

METHODS: This is a pooled analysis from three trials of patients with FMR. Key patient eligibility in these trials specified persistent grade 2+ to 4+ FMR with >5.5 cm left ventricular (LV) end-diastolic diameter (LVEDD) and reduced ejection fraction. Patients with an effective regurgitant orifice area/LV end-diastolic volume (EROA/LVEDV) ratio under 0.15 were assigned to the proportionate FMR group (n=74;65%) and those with a ratio above 0.15 were classed as having disproportionate FMR (n=39;35%).

RESULTS: At 12 months following treatment, both groups showed improvements in all MR variables including regurgitation volume, EROA and vena contracta. Moreover, in patients with proportionate MR there were clinically relevant and statistically significant improvements in LV volumes and diameters. There was no independent relationship between the degree of proportionality as a continuous variable and the remodeling response to Carillon therapy (change in LVEDV r=0.17; change in LVESV r=0.14).

CONCLUSION: Percutaneous mitral annuloplasty with the Carillon device reduces MR in patients with both proportionate and disproportionate FMR, and also results in LV reverse remodeling in those with proportionate FMR. The effect on remodeling remains to be verified in a large scale trial.