Functional outcomes with Carillon device over 1 year in patients with functional mitral regurgitation of Grades 2+ to 4+: results from the REDUCE‐FMR trial

AIMS: The objective of this study was to compare functional outcomes through 1 year in patients with core‐lab verified moderate to severe (Grades 2+ to 4+) functional mitral regurgitation (FMR) treated with the Carillon device or control in the blinded sham‐controlled REDUCE‐FMR (Carillon Mitral Contour System for Reducing Functional Mitral Regurgitation) study. METHODS AND RESULTS: The main outcomes of this analysis were the change in 6 min walk test (6MWT) distance, incidence of heart failure hospitalization or death, change in New York Heart Association (NYHA) class, and change in Kansas City Cardiomyopathy Questionnaire (KCCQ) score through 1 year of follow‐up. The minimum clinically important difference (MCID) was defined as a ≥30 m increase in 6MWT distance, an NYHA decrease in ≥1 class, and a ≥3 point increase in KCCQ score. The proportion of patients achieving the MCID in each treatment group was compared using Fisher's exact test, and the number needed to treat (NNT) with the Carillon device was calculated. Among 83 patients (62 Carillon and 21 sham), no statistically significant group differences were observed in the baseline characteristics. All outcomes at 1 year numerically favoured the Carillon group, including MCID for the 6MWT distance (59% vs. 23%, P = 0.029; NNT = 2.8), NYHA class (48% vs. 33%, P = 0.38; NNT = 6.9), KCCQ score (69% vs. 47%, P = 0.14; NNT = 4.5), and freedom from heart failure hospitalization or death (60% vs. 48%, P = 0.45; NNT = 8.3). CONCLUSIONS: REDUCE‐FMR was the first blinded sham‐controlled trial to report outcomes with percutaneous therapy for the treatment of FMR. Trends towards improvement in mean 6MWT distance, KCCQ score, and NYHA class were observed with the Carillon device. A substantially higher number of patients achieved MCID for all patient‐centred outcomes with the Carillon device compared with the sham procedure.