OBJECTIVES: Eplerenone, indicated to improve survival of stable patients with left ventricular systolic dysfunction and clinical evidence of congestive heart failure (HF) after an acute myocardial infarction (postAMI-CHF), has demonstrated to reduce all cause mortality and HF hospitalization number as well as the length of stay (LOS). The objective is to estimate total annual financial impact for an example of a tertiary Spanish hospital, based on a formulary including Eplerenone vs. without Eplerenone. METHODS: The model represents the patterns of treatment experienced by hospitalized postAMI-CHF patients during a 1-year period under the hospital perspective (2005). We estimated the annual discharges with postAMI-CHF number (422) from the total annual discharges number (62,391) and epidemiological data obtained from the literature. Estimated Eplerenone treatment mean duration was 15 days for the initial postAMI-CHF. Rates of CHF rehospitalization for postAMI-CHF patients, and the average of postAMI-CHF hospitalization LOS were obtained from EPHESUS. Only direct costs were included: adquisition drug and CHF hospitalization. Results are detailed as hospital net cost (postAMI-CHF hospitalizations and inpatient Eplerenone treatment) and incremental budgetary impact of having Eplerenone in the formulary. A sensitivity analysis was carried out varying hospitalization costs and hospitals mean LOS. RESULTS: Annual costs incurred due to postAMI-CHF hospitalizations were €128,373 with Eplerenone (Drug cost: €12,817) and €176,022 without Eplerenone. The hospital savings were €47,649, which represents an annual saving of 27% with regard to the total expense in these patients. The use of Eplerenone is overcompensated by the number of rehospitalization and LOS reduction. Sensitivity analysis results show an annual saving between €23,274 and €102.932. CONCLUSIONS: Using a simulation of what would happen in an example of a Spanish tertiary hospital, the use of Eplerenone is associated with a cost saving, under the perspective of the hospital, due to less rehospitalizations and length of stay.