Background: In the randomized COAPT trial (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation), among 614 patients with heart failure with 3+ or 4+ secondary mitral regurgitation (MR), transcatheter mitral valve repair (TMVr) with the MitraClip reduced MR, heart failure hospitalizations, and mortality and improved quality of life compared with guideline-directed medical therapy (GDMT) alone. We aimed to examine the prognostic relationship between MR reduction and outcomes after TMVr and GDMT alone. Methods: Outcomes in COAPT between 30 days and 2 years were examined on the basis of the severity of residual MR at 30 days. Results: TMVr-treated patients had less severe residual MR at 30 days than GDMT-treated patients (0/1+, 2+, and 3+/4+: 72.9%, 19.9%, and 7.2% versus 8.2%, 26.1%, and 65.8%, respectively [ P <0.0001]). The rate of composite death or heart failure hospitalizations between 30 days and 2 years was lower in patients with 30-day residual MR of 0/1+ and 2+ compared with patients with 30-day residual MR of 3+/4+ (37.7% versus 49.5% versus 72.2%, respectively [ P <0.0001]). This relationship was consistent in the TMVr and GDMT arms ( P _interaction =0.92). The improvement in Kansas City Cardiomyopathy Questionnaire score from baseline to 30 days was maintained between 30 days and 2 years in patients with 30-day MR ≤2+ but deteriorated in those with 30-day MR 3+/4+ (–0.3±1.7 versus –9.4±4.6 [ P =0.0008]) consistently in both groups ( P _interaction =0.95). Conclusions: In the COAPT trial, reduced MR at 30 days was associated with greater freedom from death or heart failure hospitalizations and improved quality of life through 2-year follow-up whether the MR reduction was achieved by TMVr or GDMT. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01626079.