Background: Frailty syndrome (FS) is a syndrome characterized by a reduction in the body’s physiological reserves as a result of the accumulation of reduced efficiency of many organs and systems. Experts of the Heart Failure Association of the European Society of Cardiology (ECS) emphasize the need to assess frailty in all patients with heart failure (HF). There is no specific scale dedicated to this group of patients. The aim of the study was to assess the occurrence of the frailty syndrome in heart failure using the multidimensional Edmonton Frailty Scale (EFS). Methods: The study included 106 patients diagnosed with heart failure with reduced left ventricular ejection fraction (LVEF < 40%). The average age was 62.6 ± 9.7 years. Most of the patients (84%) studied were men. In 70 people (66%), the cause of heart failure was coronary artery disease. The study group included patients admitted to hospital on a scheduled basis and with exacerbation of heart failure. Frailty was measured using the EFS before discharge from the hospital. Demographic, sociodemographic and clinical data were obtained. A 12-month follow-up period was included in the project. The number of readmissions after 6 and 12 months was assessed. Results: A correlation was observed between the New York Heart Association (NYHA) functional class and the occurrence of frailty—this applies to the assessment at the beginning and at the end of hospitalization. When analyzing the age of the patients in relation to frailty, a statistically significant difference was obtained. The youngest group in terms of age were non-frail patients. Hospitalization of people prone to development of the frailty syndrome and diagnosed with the FS was significantly more often associated with the occurrence of complications during hospital stays. Rehospitalizations for exacerbation of heart failure were much more frequent in patients with frailty. Conclusions: Assessment and monitoring of the state of increased sensitivity to the development of frailty or FS in patients with heart failure should influence the differentiation of clinical management. The Edmonton Questionnaire may be a helpful tool for the assessment of frailty in hospitalized patients with HF.