Methods and resultsProspective multicenter registry that included 499 HF outpatients ≥75 years old. Mean age was 81.4 ± 4.3 years, and 193 (38%) were women. Compared with men, women were older (81.9 ± 4.3 vs. 81.0 ± 4.2 years, p = 0.03) and had higher left ventricular ejection fraction (46 vs. 40%, p < 0.001) and less ischemic heart disease (30 vs. 57%, p < 0.001). Women had a higher prevalence of frailty (22 vs. 10% with Clinical Frailty Scale, 34 vs. 15% with FRAIL, and 67% vs. 46% with the mobility visual scale, all p-values < 0.001) and other geriatric conditions (Barthel index ≤90: 14.9 vs. 6.2%, p = 0.003; malnutrition according to Mini Nutritional Assessment Short Formulary ≤11: 55% vs. 42%, p = 0.007; Pfeiffer cognitive test's errors: 1.6 ± 1.7 vs. 1.0 ± 1.6, p < 0.001; depression according to Yesavage test; p < 0.001) and lower comorbidity (Charlson index ≥4: 14.1% vs. 22.1%, p = 0.038). Women also showed worse self-reported quality of life (6.5 ± 2.1 vs. 6.9 ± 1.9, on a scale from 0 to 10, p = 0.012). In the univariate analysis, frailty was an independent predictor of mortality in men [Hazard ratio (HR) 3.18, 95% confidence interval (CI) 1.29–7.83, p = 0.012; HR 4.53, 95% CI 2.08–9.89, p < 0.001; and HR 2.61, 95% CI 1.23–5.43, p = 0.010, according to FRAIL, Clinical Frailty Scale, and visual mobility scale, respectively], but not in women. In the multivariable analysis, frailty identified by the visual mobility scale was an independent predictor of mortality (HR 1.95, 95% CI 1.04–3.67, p = 0.03) and mortality/readmission (HR 2.06, 95% CI 1.05–4.04, p = 0.03) in men.