This retrospective cohort study investigates the effects of SGLT2 inhibitor therapy on erythropoiesis and its association with cardiac and renal outcomes in patients with chronic heart failure. The study will compare hematological parameters, echocardiographic measures, and clinical outcomes between patients who initiated SGLT2 inhibitor therapy and a matched control group receiving guideline-directed medical therapy alone over a 12-month follow-up period.

The study is designed as a retrospective cohort analysis of patients with chronic heart failure who attended the outpatient heart failure clinics at University Medical Centre Ljubljana between January 1, 2019, and December 31, 2023. Patients will be divided into two groups: those who initiated SGLT2 inhibitor therapy (empagliflozin or dapagliflozin 10 mg daily) and a control group of comparable patients receiving guideline-directed medical therapy without SGLT2 inhibitors. Data will be extracted from electronic medical records at baseline, 6 months, and 12 months. The primary focus is on changes in erythropoietic parameters (hemoglobin, hematocrit, red blood cell count, red cell distribution width) and their association with changes in cardiac function (LVEF, NTproBNP, NYHA class) and renal function (eGFR, serum creatinine).

Inclusion Criteria:

• Diagnosis of chronic heart failure
• Receiving guideline-directed medical therapy for heart failure for at least 3 months prior to inclusion
• Age ≥18 years

Exclusion Criteria:

• Incomplete or missing data in electronic medical records
• Acute cardiac event within 3 months prior to baseline
• Active malignancy or hematological disease affecting erythropoiesis
• Use of erythropoiesis-stimulating agents or regular erythrocyte transfusions during the observation period
• Severe renal insufficiency (eGFR <15 mL/min/1.73m²)
• Severe liver insufficiency (AST/ALT >3× upper limit of normal, bilirubin >2× upper limit of normal)
• Known allergy to any SGLT2 inhibitor component
• Pregnancy or breastfeeding

Patients with chronic heart failure on guideline-directed medical therapy.

Deidentified individual participant data (IPD) that underline the results reported in future publications (text, tables, figures, and appendices) will be shared upon reasonable request. Shared IPD will include baseline characteristics, outcome measures, and relevant biomarker data, excluding data that could compromise participant privacy or institutional confidentiality.

IPD will be made available within 6 months after publication of the main results and will remain accessible for at least 5 years thereafter.

Researches whose proposed use of the data is approved by the principal investigator will be granted access. Proposals should include a concise research plan and statistical analysis outline. Request should be submitted to gregor.poglajen@kclj.si. Approved requesters will sign a data sharing aggrement to ensure data confidentiality and appropriate use.