Patients with heart failure (HF) are limited by symptoms and have impaired quality of life. The Kansas City Cardiomyopathy Questionnaire (KCCQ) is a patient-reported outcome measure that enables evaluation of the effect of HF and the impact of new therapies on health status in patients with HF.This prespecified analysis of FINEARTS-HF (Finerenone Trial to Investigate Efficacy and Safety Superior to Placebo in Patients With Heart Failure) assessed the efficacy and safety of finerenone according to baseline KCCQ Total Symptom Score (TSS) and the effect of finerenone on KCCQ-TSS.FINEARTS-HF tested the efficacy of the nonsteroidal mineralocorticoid receptor antagonist (MRA) finerenone, compared with placebo, in patients with HF with mildly reduced ejection fraction/preserved ejection fraction. The primary endpoint was the composite of cardiovascular death and total worsening HF events. The KCCQ was completed by patients at randomization and at 6, 9, and 12 months after randomization. Change in KCCQ-TSS was a key secondary endpoint. Patients were stratified by KCCQ-TSS tertiles at baseline. The association between KCCQ tertile and clinical outcomes was evaluated using semiparametric proportional-rates models for total events and Cox models for time-to-first-event data, and the effects of finerenone vs placebo on the primary endpoint were assessed across tertiles of KCCQ-TSS.Of the 6,001 participants in FINEARTS-HF, 5,986 (99.8%) had baseline KCCQ-TSS recorded (median score 69.8 of a possible 100; higher score = better health status). Lower (worse) KCCQ-TSS was associated with a higher risk of the primary endpoint. Finerenone, compared with placebo, reduced the risk of the primary endpoint across the range of KCCQ-TSS: tertile 1 (score 0-<57): RR: 0.82 (95% CI: 0.68-1.00); tertile 2 (57-<81): 0.88 (95% CI: 0.70-1.11); tertile 3 (81-100): 0.88 (95% CI: 0.69-1.14) (Pinteraction = 0.89). Compared with placebo, finerenone significantly improved KCCQ-TSS from baseline with a mean difference at 12 months of 1.62 points (95% CI: 0.69-2.56 points) (P < 0.001). Numerically fewer finerenone-treated patients experienced clinically meaningful deterioration, and more had improvements in KCCQ-TSS.Finerenone significantly reduced HF events and improved health status in patients with HF and mildly reduced ejection fraction/preserved ejection fraction across the spectrum of KCCQ-TSS at baseline. (Study to Evaluate the Efficacy [Effect on Disease] and Safety of Finerenone on Morbidity [Events Indicating Disease Worsening] & Mortality [Death Rate] in Participants With Heart Failure and Left Ventricular Ejection Fraction [Proportion of Blood Expelled Per Heart Stroke] Greater or Equal to 40% [FINEARTS-HF], NCT04435626; Finerenone Trial to Investigate Efficacy and Safety Superior to Placebo in Patients with Heart Failure; EudraCT 2020-000306-29).