Guidelines recommend the use of renin-angiotensin-aldosterone-system inhibitor (RAASi) therapy to reduce the risk of hospitalization and mortality of patients with heart failure (HF), and clinical studies demonstrate the benefits of RAASi therapy in these patients. Contrary to this evidence, RAASi therapy is often down-titrated, discontinued, or not initiated in patients, in particular those with impaired renal function, because of the risk or presence of comorbid hyperkalemia. Novel potassium binders that remove excess potassium are now available, and clinical studies have shown that novel binders enable patients with HF to initiate and maintain target doses of RAASi therapy via long-term serum potassium control. A greater understanding is still needed of real-world RAASi treatment patterns in patients with HF and how these treatment patterns relate to serum potassium status and potassium binder use. The CARE HK in HF study is an observational, multinational, non-interventional study designed to investigate treatment patterns and influences affecting RAASi target dosing in relation to hyperkalemic events and the initiation of patiromer. Prospective patient follow-up will occur for 24 to 48 months. Primary endpoints of the study include a comparison of the level of RAASi optimization at initiation of patiromer treatment, in response to hyperkalemia events, and short- and long-term titration following hyperkalemic events. Additionally, the percentage of patiromer-treated and untreated patients will be compared according to the level of RAASi optimization at short- and long-term titration following hyperkalemia events.