Abstract Since the introduction of the ESC guidelines in 2021 and the increased level of recommendations in 2023, SGLT2 inhibitors (SGLT2i) have been widely used in all patients with heart failure (HF), improving their prognosis. Current guidelines recommend the use of SGLT2i across the entire spectrum of HF regardless of ejection fraction. The aim of the study was to summarize the usage of SGLT2i in patients with HF in Poland, based on data gathered in the Heart Failure Observational Study (HEROES) conducted by the Polish Cardiac Society. Overall, 1176 patients (enrolled between Feb 2022 and Jun 2023) were included in the analysis (hospitalizations: N=918, outpatient visits: N=258). Most of them were men (71.7%) with a median age of 69 years (IQR: 60-75). Patients with reduced ejection fraction (HFrEF) were the most numerous group (48%, N=565) followed by preserved (HFpEF, 22%, N=259) and mildly reduced (HFmrEF, 14%, N=166) ejection fraction. In 16% of cases, ejection fraction was not reported. Only fewer than 60% of subjects were reported to be treated with SGLT2i (overall: 59.5%; HFrEF: 82.3%; HFmrEF: 48.8%, HFpEF: 32.4%). We divided the whole study group into 4 even quartiles based on the number of consecutive patients enrolled (Q1: Feb 2022-Dec 2022; Q2: Sep 2022; Q3: Mar 2023; Q4: Jun 2023). Results showed an overall increasing number of patients treated with SGLT2i in consecutive quartiles, especially in HFmrEF group (Fig. 1). However, in the last quartile (Q4), less than 40% usage of SGLT2i in HFpEF patients was observed (38.2%). The analyzed period ended before the release of the 2023 focused update of HF guidelines that strengthened recommendations for SGLT2i use to the first class of recommendations regardless of ejection fraction. This document will probably further increase the usage of SGLT2i in the Polish HF population. Nevertheless, our data are worrying, as overall more than 1/3 of HF patients in the last quartile were not treated with one of the basic and effective drugs in HF. It is worth mentioning that the 2021 HF guidelines recommended SGLT2i in the first class of recommendations only in HFrEF, but by that time, current clinical trial results had already shown great benefit in HFmrEF and HFpEF patients.SGLT2i treatment in PL (Feb2022-Jun2023)