This is a multicenter, observational, prospective, national study which includes patients with chronic kidney disease (CKD) under dialysis or not, or with heart failure (HF), treated with sodium zirconium cyclosilicate (SZC) as per Summary of Product Characteristics (SmPC), aiming to collect information on patient characteristics, routine clinical practice and treatments administered for managing hyperkalaemia in a real-world setting in Greece. It will include approximately 12 public hospital and clinic based nephrology, or cardiology sites throughout the country. Sites and investigators will be selected so to represent the management of patients with CKD under dialysis or not, or with HF receiving Renin angiotensin aldosterone inhibitors/Mineralocorticoid receptor antagonists (RAASi/MRAs) therapy, and treated with sodium zirconium cyclosilicate (SZC) as per SmPC at a national level. The final selection of the participating sites will be based on a documented feasibility evaluation process that will assess physicians' qualifications, previous participation, and experience in similar clinical studies. Data will be obtained prospectively during the study visits as performed per standard clinical practice. Data regarding the patient's medical history will be collected retrospectively from patient medical charts records. Physicians will monitor eligible patients and will record their management according to their usual clinical practice. Only medical records available from the clinical practice and provided by the physicians will be used in this study as source documentation and the data will be entered into the electronic Case Report Form. Therefore, the collected data will reflect usual clinical practice. The study will enroll approximately 120 hyperkalaemia patients with serum potassium level >5.0 mmol/L, being treated with sodium zirconium cyclosilicate for hyperkalaemia at the time of enrolment as per SmPC, assigned in a 2:1:1 ratio to one of the following 3 groups: (1) CKD patients not on dialysis (60 patients), (2) CKD patients on dialysis (30 patients) and (3) HF patients receiving RAASi/MRAs therapy (30 patients), all consisting the study population. Patients will be followed for 6 months, with a 6-month recruitment period, for a total study duration of 12 months.
