Objectives: * To create an observational registry of all patients hospitalized for a AHF * To determine the precise prevalence of etiologies and the prognostic factors of AHF in a non selected population. Among the prognostic factors, to establish the specific role of acute renal failure * To establish the optimal initial assessment of patients hospitalized for heart failure * To validate and compare with prospective data the results of a retrospective cohort study carried out at the University Hospital of Geneva who established the re-hospitalization and mortality outcome of patients hospitalized for heart failure. Method: Creation of an observational registry associated with a biobank including patients hospitalized for AHF in the Department of General Internal medicine (SMIG) and in the Departments of Specialties at the University Hospital of Geneva. Anticipated results: * To identify the prevalence of the etiologies and the prognostic factors of the heart failure * To establish the optimal initial assessment of the patients hospitalized for a heart failure. Among the prognostic factors, to establish the specific role of acute renal failure * To validate and compare results of a retrospective cohort study carried out at the University Hospital of Geneva which established the re-hospitalization and mortality outcome of patients hospitalized AHF * To improve the management of hospitalized patients with AHF with a robust identification of the etiologies and a better identification of high-risk patients.