Abstract Background/Introduction Heart failure (HF) presents as a clinical syndrome associated with an adverse prognosis, increased mortality risk, and recurrent hospitalizations for HF (HHF). In Poland, there has been a persistent increase in the overall prevalence and hospitalizations of HF among patients. Each subsequent HHF is associated with progressively worsening prognosis. In Europe, HF is most prevalent in elderly individuals, rendering this patient group particularly susceptible to HF exacerbations. Purpose The aim of this study was to conduct a comprehensive analysis of the oldest patients (≥80 years) hospitalized due to HF decompensation, compared to the rest of the evaluated cohort, including overall mortality after median 46 months of observation. Methods The prospective registry of patients with HF decompensation (LECRA-HF) is an ongoing registry conducted at a tertiary cardiology center specializing in HF treatment. Patients enrolled in the registry (n=1394) were evaluated for the presence of cardiovascular risk factors, HF phenotype, laboratory, and echocardiographic findings, as well as overall mortality. Due to the frequent occurrence of HF in elderly patients, we arbitrarily chose to compare two cohorts of patients: those above (n=306) vs. below 80 years of age (n=1088). Results Median age of elderly patients was 84 [82-86] years, of which only 7.8% were >90 years of age. HFrEF was the most common HF phenotype, which, occurred less frequently in the elderly (54.4 vs 74.4%, P<0.001). In turn, HFpEF was more prevalent in elderly group (39.2 vs 17.7%, P<0.001). Elderly patients were more often female (45.1 vs 30.2%, P<0.001) and had more comorbidities: arterial hypertension (85.6 vs 78.6%, P=0.007), atrial fibrillation (61.1 vs 45.7%, P<0.001), renal failure (49.7 vs 28.5%, P<0.001) as well as peripheral arterial disease (17 vs 9.8%, P=0.005). Those patients had more frequently implanted cardiac pacemakers (28.6 vs 12.6%, P<0.001), but less often implantable cardioverter-defibrillators (7.9 vs 14.3%, P=0.003). During HHF they were less often qualified to elective coronary angiography (24.2 vs 31.5%, P=0.039). At discharge mineralocorticoid receptor antagonist were less often prescribed in that group (42.4 vs 50.3%, P=0.010). During long-term observation patients ≥80 years had a higher all-cause mortality (81 vs 67.4%, P<0.001, Panel A). Moreover, it was also higher elderly with NT-proBNP>4497 pg/mL (P<0.001) and LVEF<41% (P=0.014) (Panel B). Conclusion(s) Patients aged ≥80 years were characterized by a higher burden of comorbidities. They were more often qualified to cardiac pacemakers, but less often to implantable cardioverter-defibrillators and invasive coronary procedures. The most common HF phenotype was HFrEF, however with a significant increase in HFpEF. They exhibited significantly higher overall mortality compared to those <80 years old, which was associated with both LVEF and NT-proBNP levels.