**1. Introduction**

Chronic HF is a common complication of cardiovascular diseases. The widespread prevalence of this pathology in the world in recent years has taken on the scale of an epidemic. Tens of millions of people around the world suffer from this disease. It can be made with the growing burden of obesity-related diseases and with the aging of the population [1]. Probably, it is also important to increase the survival rate after acute forms of coronary artery disease and increase the life expectancy of patients with HF. Diagnosis of chronic HF is a major clinical problem, especially in patients with comorbidities [2]. This Chapter aims to highlight the features of the diagnosis of HF in an outpatient setting.

## **2. The prevalence of heart failure among patients in outpatient practice**

The reasons for visiting a polyclinic by patients are often acute diseases, the need for a health examination, or dispensary monitoring for chronic diseases. The cohort of such visitors does not accurately reflect the state of the population, but these are the people that outpatient doctors have to deal with.

Many variants of criteria for the diagnosis of heart failure in epidemiological studies have been developed. Their diversity highlights the inferiority of diagnostic methods. There are Framingham, Gothenburg, Boston, European society of cardiology criteria and others. We used a questionnaire proposed by the Russian society of heart failure specialists [3]. The questionnaire includes a question about the presence of shortness of breath, confirmation of myocardial damage by instrumental methods, taking diuretics, a known diagnosis of heart failure, and a decrease in the left ventricular ejection fraction of less than 50%. A positive answer to the first question and any subsequent question makes it likely that the patient has HF.

In a survey of 3,000 adults who consecutively applied to the outpatient clinic, it was found that 543 patients were suspected of heart failure. The recruitment of people in the study was carried out by age and gender groups identical to the population living in the city. Among people who visit an outpatient department, the clinical suspicion of heart failure among men is 12.3%, among women it reaches 22.9% [4]. At the same time, it is possible to confirm the presence of heart failure in 11.7% of outpatient patients. In 36.2% of outpatient visitors with suspected HF, the disease is not confirmed during further examination. These cases were 57% more common among women compared to men.

The specificity of the questionnaire used was 63.8%. Thus, after clinical screening for possible HF, additional methods should be used that exclude the situation of overdiagnosis.

The vast majority of patients (87%) have HF with preserved ejection fraction (EF). However, among hospitalized patients with heart failure, the ratio between preserved and reduced ejection fraction is approximately one to one [5].
