In individuals with heart failure (HF) and significant secondary mitral regurgitation (MR), baseline renal dysfunction (RD) had a negative impact on outcomes. Heart failure and MR exacerbate the prognosis by hastening the progression of end-stage renal disease (ESRD). For a study, the researchers sought to find how RD affected new-onset ESRD and the need for renal replacement therapy in HF patients with severe MR. They also sought to determine how TMVr affected new-onset ESRD and the need for renal replacement therapy (RRT). The COAPT research compared MitraClip with guideline-directed medical therapy (GDMT) vs GDMT alone in 614 patients with HF and severe MR. Based on their baseline estimated glomerular filtration rate (eGFR, mL/min/1.73 m2), patients were divided into 3 RD subgroups: none (≥60), moderate (30–60), and severe (<30). RRT or eGFR 15 mL/min/1.73 m2 was used to define end-stage renal illness. The 2-year rates of all-cause death, HF hospitalization (HFH), new-onset ESRD, and RRT were calculated based on the RD and therapy. About 77.0% of patients had RD at the start, with 23.8% having severe RD, 6.0% having ESRD, and 5.2% having RRT. A higher 2-year risk of mortality or HFH was related to worse RD (none 45.3%; moderate 53.9%; severe 69.2%; P<0.0001). MitraClip vs GDMT alone improved outcomes regardless of RD (Pinteraction=0.62) and reduced new-onset ESRD [2.9 vs 8.1%, HR 0.34, 95% CI 0.15–0.76, P=0.008] and the need for new RRT (2.5 vs 7.4%, HR 0.33, 95% CI 0.14–0.78, P=0.011).