**Abstract**

The Chapter contains information about the prevalence of heart failure (HF) among patients in outpatient practice. The causal structure of HF, the prevalence of risk factors for HF, and the occurrence of a reduced ejection fraction are described. It describes the frequency of overdiagnosis of HF, the disease most often simulating its symptoms. The difficulties associated with laboratory and instrumental diagnostics of this syndrome are discussed. A pharmacological test for differential diagnosis of the causes of dyspnea in patients with suspected HF is described. Information is provided on the incidence of depressive and anxiety among the patients with this disease.

**Keywords:** heart failure, prevalence, outpatient, diagnostics, differential diagnostics, pharmacological test, torasemide, depressive, anxiety
