PROJECT SUMMARY/ABSTRACT Heart failure (HF) is a leading global public health problem. The burden of HF is increasing in low- and middle- income countries and clinical outcomes remain poor. Guideline-directed medical therapy (a combination of distinct medications from disparate drug classes) improves morbidity and mortality in patients with HF with reduced ejection fraction (HFrEF). Despite this high-quality evidence, guideline-directed medical therapy remains widely underutilized globally and specifically in India. This gap represents a key target for intervention to save lives. Dr. Agarwal’s K99/R00 proposal aims to substantially simplify HF management by shifting the treatment paradigm for undertreated patients with HFrEF from multi-drug therapy with sequential initiation and titration to a novel late-stage implementation strategy of a HFrEF polypill of guideline-directed medical therapy including a beta-blocker, angiotensin receptor blocker, and mineralocorticoid receptor antagonist. First, Dr. Agarwal will conduct formative mixed methods research including a HF treatment consensus meeting and focus group discussions to guide development of the HFrEF polypill-based strategy in India. Second, she will evaluate whether, compared to usual care, a HFrEF polypill implementation strategy will reduce cardiovascular disease mortality and HF hospitalizations at 12 months in adults with HFrEF in India using a multi-center, type I hybrid randomized clinical trial design. She will also assess the effect of the HFrEF polypill implementation strategy on important secondary outcomes including medication adherence, markers of HF disease severity, health-related quality of life, and safety measured by adverse events. Finally, Dr. Agarwal will apply methods of process evaluation to assess implementation outcomes of the HFrEF polypill in India, a key step in translating evidence generated into broader use globally. The K99 phase will also provide essential methodological training