BACKGROUND: Patient-reported outcomes (PROs) may improve care for patients with heart failure. The Kansas City Cardiomyopathy Questionnaire-12 (KCCQ-12) is a patient survey that captures symptom frequency, symptom burden, physical limitations, social limitations, and quality of life. Despite the utility of PROs and the KCCQ-12, the implementation and routine use of these measures can be difficult. We conducted an evaluation of clinician perceptions of the KCCQ-12 to identify barriers and facilitators to implementation into clinical practice. METHODS: We conducted interviews with cardiologists from 4 institutions across the United States and Canada (n=16) and observed clinic visits at 1 institution in Northern California (n=5). Qualitative analysis was conducted in 2 rounds: (1) rapid analysis constructed around major themes related to the aims of the study and (2) content analysis with codes derived from the rapid analysis and implementation science. RESULTS: Most heart failure physicians and advanced practice clinicians reported that the KCCQ-12 was acceptable, appropriate, and useful in clinical care. Clinician engagement efforts, trialability, and the straightforward design of the KCCQ-12 facilitated its use in clinical care. Further opportunities identified to facilitate implementation include more streamlined integration into the electronic health record and comprehensive staff education on PROs. Participants highlighted that the KCCQ-12 was useful in clinic visits to improve the consistency of patient history taking, focus patient-clinician conversations, collect a more accurate account of patient quality of life, track trends in patient well-being over time, and refine clinical decision-making. CONCLUSIONS: In this qualitative study, clinicians reported that the KCCQ-12 enhanced several aspects of heart failure patient care. Use of the KCCQ-12 was facilitated by a robust clinician engagement campaign and the design of the KCCQ-12 itself. Future implementation of PROs in heart failure clinic should focus on streamlining electronic health record integration and providing additional staff education on the value of PROs. REGISTRATION: URL: https://clinicaltrials.gov; Unique identifier: NCT04164004