Importance: Transcatheter mitral valve repair (TMVr) plus maximally tolerated guideline-directed medical therapy (GDMT) reduced heart failure (HF) hospitalizations (HFHs) and all-cause mortality (ACM) in symptomatic patients with HF and secondary mitral regurgitation (SMR) compared with GDMT alone in the Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation (COAPT) trial but not in a similar trial, Multicenter Study of Percutaneous Mitral Valve Repair MitraClip Device in Patients With Severe Secondary Mitral Regurgitation (MITRA-FR), possibly because the degree of SMR relative to the left ventricular end-diastolic volume index (LVEDVi) was substantially lower.
Objective: To explore contributions of the degree of SMR using the effective regurgitation orifice area (EROA), regurgitant volume (RV), and LVEDVi to the benefit of TMVr in the COAPT trial.
Design, setting, and participants: This post hoc secondary analysis of the COAPT randomized clinical trial performed December 27, 2012, to June 23, 2017, evaluated a subgroup of COAPT patients (group 1) with characteristics consistent with patients enrolled in MITRA-FR (n = 56) (HF with grade 3+ to 4+ SMR, left ventricular ejection fraction of 20%-50%, and New York Heart Association function class II-IV) compared with remaining (group 2) COAPT patients (n = 492) using the end point of ACM or HFH at 24 months, components of the primary end point, and quality of life (QOL) (per the Kansas City Cardiomyopathy Questionnaire overall summary score) and 6-minute walk distance (6MWD). The same end points were evaluated in 6 subgroups of COAPT by combinations of EROA and LVEDVi and of RV relative to LVEDVi.
Interventions: Interventions were TMVr plus GDMT vs GDMT alone.
Results: A total of 548 participants (mean [SD] age, 71.9 [11.2] years; 351 [64%] male) were included. In group 1, no significant difference was found in the composite rate of ACM or HFH between TMVr plus GDMT vs GDMT alone at 24 months (27.8% vs 33.1%, P = .83) compared with a significant difference at 24 months (31.5% vs 50.2%, P < .001) in group 2. However, patients randomized to receive TMVr vs those treated with GDMT alone had significantly greater improvement in QOL at 12 months (mean [SD] Kansas City Cardiomyopathy Questionnaire summary scores: group 1: 18.36 [5.38] vs 0.43 [4.00] points; P = .01; group 2: 16.54 [1.57] vs 5.78 [1.82] points; P < .001). Group 1 TMVr-randomized patients vs those treated with GDMT alone also had significantly greater improvement in 6MWD at 12 months (mean [SD] paired improvement: 39.0 [28.6] vs -48.0 [18.6] m; P = .02). Group 2 TMVr-randomized patients vs those treated with GDMT alone tended to have greater improvement in 6MWD at 12 months, but the difference did not reach statistical significance (mean [SD] paired improvement: 35.0 [7.7] vs 16.0 [9.1] m; P = .11).
Conclusions and relevance: A small subgroup of COAPT-resembling patients enrolled in MITRA-FR did not achieve improvement in ACM or HFH at 24 months but had a significant benefit on patient-centered outcomes (eg, QOL and 6MWD). Further subgroup analyses with 24-month follow-up suggest that the benefit of TMVr is not fully supported by the proportionate-disproportionate hypothesis.
Trial registration: ClinicalTrials.gov Identifier: NCT01626079.