Abstract Background Heart failure (HF) is one of the most prevalent diseases. Improvements in cardiac disease management in the last two decades and in HF itself might have influenced the referral of patients with HF to a specialised HF clinic. Purpose To evaluate changes in the profile of patients referred to an outpatient HF clinic over the span of 20 years, and to analyse trends in 2-year mortality. Methods A retrospective analysis of a prospective registry of HF patients in a specialised ambulatory HF clinic was conducted, from January 1st 2002 to December 31st 2021. We divided the 20 years of the study into five periods of four years each, in order to compare the clinical characteristics of patients at admission. The variables analysed include age, sex, aetiology, HF type (preserved - HFpEF, reduced - HFrEF, mildly-reduced - HFmrEF), NYHA class, left ventricle ejection fraction (LVEF), NT-proBNP level, number of previous hospitalizations, and treatment at referral (first visit). Two-year mortality was also analysed. Results A total of 2973 patients were included (mean age 67.1± 12,9, 69.7% men). Age remained stable across the five periods, p=0.43), while the referral of women increased throughout the study period (27.7% in 2002-2005 vs 32.9% in 2018-2021, p-for-trend=0.037). Patients with HFpEF were also increasingly referred (12.3% first period vs. 27.6% last period, p-for-trend<0.001) and LVEF tended to be higher (33.09% vs. 40,9%, p<0.001). The main aetiology of the referred patients was ischaemic heart disease, although it progressively decreased in favour of other aetiologies (Table 1) (p<0.001). NYHA class tended to improve (NYHA 3-4 40.3% vs. 21.3%, p-for-trend <0.001) and NT-proBNP levels tended to decrease, predominantly in the last period (p-for-trend=0.025), as well as hospitalisation rates in the previous year (p-for-trend<0.001). Treatment with ACEi/ARB was progressively less frequent (p<0.001), at least partially due to replacement by ARNi (p<0.001). Treatment with digoxin and loop diuretics also diminished (p<0.001 and p=0.04 respectively), whereas treatment with betablockers, ARM, ivabradine and SGLT-2i increased during the study periods (all p<0.001) (Table 2); Patients carrying ICD and CRT also increased (p=0.014 and p<0.001 respectively). Adjusted 2-year mortality significantly decreased, mainly in the last period (p<0.001) (Figure 1). Conclusion The profile of HF patients referred to a tertiary HF ambulatory Clinic changed along 20 years of study. HFrEF remained the most common, but is declining in favour of HFpEF. Ischaemic aetiology also remained the most frequent but, again, showed a decreasing trend. Two-year mortality has globally decreased, markedly in the last period.Figure 1