Aims: Frailty is highly prevalent in patients with heart failure (HF), but a concordant definition of this condition is lacking. The Heart Failure Association of the European Society of Cardiology (HFA-ESC) proposed in 2019 a new multi-domain definition of frailty, but it has never been validated. Methods and results: Patients from the HELP-HF registry were stratified according to the number of HFA-ESC frailty domains fulfilled and to the cumulative deficits frailty index (FI) quintiles. Prevalence of frailty and of each domain was reported, as well as the rate of the composite of all-cause death and HF hospitalization, its single components, and cardiovascular death in each group and quintile. Among 854 included patients, 37 (4.3%), 206 (24.1%), 365 (42.8%), 217 (25.4%), and 29 (3.4%) patients fulfilled zero, one, two, three, or four domains, respectively, while 179 patients had a FI < 0.21 and were considered not frail. The 1-year risk of adverse events increased proportionally to the number of domains fulfilled (for each criterion increase, all-cause death or HF hospitalization: hazard ratio [HR] 1.43, 95% confidence interval [CI] 1.27-1.62; all-cause death: HR 1.72, 95% CI 1.46-2.02, HF hospitalizations: subHR 1.21, 95% CI 1.04-1.31; cardiovascular death: HR 1.77, 95% CI 1.45-2.15). Consistent results were found stratifying the cohort for FI quintiles. The FI as a continuous variable demonstrated higher discriminative ability than the number of domains fulfilled (area under the curve = 0.68 vs. 0.64, p = 0.004). Conclusion: Frailty in patients at risk for advanced HF, assessed via a multi-domain approach and the FI, is highly prevalent and identifies those at increased risk of adverse events. The FI was found to be slightly more effective in identifying patients at increased risk of mortality.
