Aim. To determine the prevalence and show the features of the development of newly diagnosed heart failure (HF) in patients with dyspnea after a coronavirus disease 2019 (COVID-19).Material and methods. This clinical prospective observational study was conducted during 2020-2022. The study consecutively included 368 outpatients with shortness of breath, who applied to the clinic. Depending on the presence of prior COVID-19, the patients were divided into 2 groups: the first group consisted of 205 patients with shortness of breath after COVID-19, the second group — 163 patients without prior COVID-19. All patients underwent a clinical examination within 3 days after presentation with an assessment of outpatient records and other medical documents for the differential diagnosis of dyspnea. The severity of dyspnea was determined using the Modified Medical Research Council Dyspnoea Scale (mMRC). The diagnosis of HF was verified in accordance with the 2020 Russian Society of Cardiology guidelines and in some cases reclassified in accordance with the 2021European Society of Cardiology guidelines. For further analysis, 2 subgroups of patients with HF were identified depending on the presence and absence of prior COVID-19. The subgroup analysis excluded patients with acute heart failure, acute illness, and conditions requiring hospitalization and/or intensive care.Results. Among 368 patients who presented to the clinic with dyspnea during 2020-2022, 205 patients (55,7%) had COVID-19. The average period of treatment after COVID-19 was 3,5 [1,5; 22,4] months. Patients after COVID-19 applied earlier after the onset of dyspnea, which is associated with higher mMRC score. The prevalence of HF among patients with shortness of breath after COVID-19 was significantly higher than in patients without this pathology in history, and amounted to 19,0% vs 9,8% (p=0,021). Prior COVID-19 increased the relative risk (RR) of HF in patients with shortness of breath by 1,7 times. RR for HF in systolic blood pressure >140 mm Hg increased by 1,9 times, while in diastolic blood pressure >90 mm Hg — by 1,9 times, with the development of a hypertensive crisis — by 28%, with a heart rate >80 bpm at rest — by 1,4 times, with the development of type 2 diabetes — by 31%, in the presence of pulmonary fibrosis — by 2,3 times. Patients with shortness of breath after COVID-19 had more severe HF, both according to clinical tests and according to the blood concentration of N-terminal pro-brain natriuretic peptide (NT-proBNP), mainly with the preserved ejection fraction (EF) with a higher prevalence of left atrial (LA) enlargement in combination with a decrease in right ventricular (RV) systolic function and its dilatation. In patients after COVID-19 in the presence of chronic kidney disease, the RR for HF increased by 4,5 times; in the presence of C-reactive protein >4 mg/l — by 1,6 times.Conclusion. Every fifth patient with shortness of breath 3,5 months after COVID-19 had more severe HF, both according to clinical tests and according to blood NT- proBNP concentration, mainly with preserved EF with a higher prevalence of LA increase in combination with a decrease in RV systolic function and its dilatation. The risk of HF is interrelated with the female sex and multiple comorbidities.