BACKGROUND: Despite randomized data for survival benefit (with class 1 recommendations) for treating heart failure (HF) with reduced ejection fraction using quadruple medical therapy (QMT)—defined as evidence-based β-blockers, sodium-glucose cotransporter 2 inhibitor, preferably angiotensin receptor/neprilysin inhibitor, and mineralocorticoid receptor antagonist—it is underutilized. IMPLEMENT-HF is a multiregional HF quality improvement initiative to improve care and outcomes for patients with HF by enhancing the use of QMT in routine practice. METHODS: This analysis of HF with reduced ejection fraction treatment in patients from hospitals participating in the American Heart Association’s Get With The Guidelines–HF who volunteered to participate in IMPLEMENT-HF in 7 US regions. IMPLEMENT-HF included multidisciplinary learning to share strategies for formulary changes, electronic health record tools, and patient resources with site-level feedback reports. Participants gathered QMT data