Chronic heart failure (HF) is a disabling condition with a rising prevalence, especially in the elderly (Bui et al., 2011). The clinical hallmark of the disease is a reduced tolerance to physical exercise (Piepoli et al., 2010). Compared to healthy subjects, chronic HF patients exhibit a reduction of peak aerobic capacity and early onset of dyspnea and fatigue (Ponikowski et al., 2016).

In chronic HF, aerobic exercise tolerance usually relates to habitual physical activity level, and progression of HF symptoms is associated with a progressive decrease of patients’ habitual activities (Mezzani et al., 2000).

Elderly chronic HF patients often complain of greater limitations when performing Activities of Daily Living (ADLs; Holland et al., 2010; Dunlay et al., 2015). In particular, older subjects describe a debilitating and distressing condition during daily life situations, due to several detrimental physical and psychosocial issues (Yu et al., 2008).

Spruit et al. (2011) have shown that, differently from healthy elderly subjects, chronic HF elderly patients had an oxygen uptake at a higher proportion of their peak aerobic capacity, and compared to healthy elderly subjects have a higher heart rate and greater ventilation (VE) during simple activities, such as getting dressed, folding towels, or cleaning the floor.

Moreover, Mapelli et al. (2020) recently observed that, in severe chronic HF patients with reduced ejection fraction (HFrEF), the VO₂ used during ADLs tasks was even higher of peak VO₂ at cardiopulmonary exercise test (CPET), with a respiratory exchange ratio around or above 1. Moreover, patients were able to compensate for the high percentage of peak VO₂ needed for a given ADL by prolonging the time needed to complete the task (Mapelli et al., 2020).

Cardiac rehabilitation (CR), which consists in a multidisciplinary and comprehensive treatment including exercise training, drug management, lifestyle modification, and psychosocial counseling, is recommended for the long-term management of HFrEF (Ponikowski et al., 2016). Aerobic exercise training is one component of CR, as its benefit in improving peak exercise capacity, increasing the tolerance to exercise, and reducing the impact of dyspnea and fatigue on the individual’s functional capacity have been widely demonstrated (Taylor et al., 2014).

However, the improvement of exercise tolerance could not always translate into an increased ability to perform functional activities, such as ADLs.

Because the improvement in the ability to perform tasks is an important goal for patients attending CR, more insights are needed on the possible beneficial effects of CR on the performance during ADLs, in terms of symptoms, time spent, and physiological response to the activity.

Single physiotherapy interventions, such as resistance training, can improve the ability of chronic HF patients to perform ADLs (Savage et al., 2011). However, to our knowledge, no studies yet have evaluated the effects of a CR intervention on ADLs performance.

Therefore, the present study aimed to describe the metabolic response during ADLs in elderly HF patients, before and after a residential CR program. Secondary aims were to describe: (a) the change in time necessary to perform five time-related ADLs (b) the modifications of heart rate and symptoms (c) the differences in response between patients in NYHA class 2 and 3 between patients with and without reduced ejection fraction (EF). The hypothesis was that CR might influence metabolic requests during ADL improving efficiency of tasks.

This was a prospective, multicenter, observational study performed at the Cardiac Rehabilitation Department of the Istituti Clinici Scientifici Maugeri IRCCS Network, Italy in the rehabilitative hospitals of Lumezzane (BS), Montescano (PV), Tradate (VA), and Pavia (PV). The study was approved by the local Ethical Committee (CE n. 2204, date 29/05/2018). All participants gave written informed consent to participate in the study.

Table 1 shows the baseline demographic, anthropometric, and clinical characteristics of HF patients enrolled in the study. The mean age was 72 ± 5 years. Patients were mainly male (80%), with moderate HF: more than 30% of patients were in NYHA class 3. Mean NT-proBNP was measured in 83 patients and was 2,559 ± 4,511 pg/ml. About 60% of patients had left ventricular EF lower than 40% and two or more comorbidities were present in 60% of patients. Fifty-six percent of patients had an ICD or CRT device implanted according to ESC guidelines recommendations (Ponikowski et al., 2016), while 90% received an angiotensin-converting enzyme inhibitor or one of its alternative and beta-blockers. No major differences in clinical characteristics emerged when patients were grouped according to NYHA functional class 2 or 3 other than a higher prevalence of kidney dysfunction among NYHA class 3 patients.

Resting metabolic parameters (VO₂ = 320 ± 111 ml/min, VCO₂ = 249 ± 97 ml/min, RER =0.78 ± 0.16, VE = 12.7 ± 3.6 L) did not change after CR.

Table 2 describes metabolic values and dyspnea symptoms at the end of each ADL before and after CR in the overall group and in NYHA class 2 and 3 subgroups.

After CR, Task VO₂ did not change in none of the domestic ADLs, apart in ADL4 (p = 0.045) and in 6MWT (p = 0.005). Task aerobic work showed a significant reduction in two out of the six domestic ADLs (ADL1 and ADL6, p = 0.019 and p = 0.003 respectively).

Notably, for non-fixed execution and speed ADLs, there was a decrease in the cumulative time required to perform the task-related activities (ADL 1–4 and ADL6; from 412 ± 147 to 388 ± 141 s, p = 0.001, Figure 1). Moreover, we found a pre-to-post reduction in maximal HR during ADL1 and ADL3 (p = 0.005 and p = 0.027, respectively) and a reduction of dyspnea during ADL6 (p = 0.004).

For the fixed execution and non-fixed speed activities (ADL5 and 6MWT), we observed a relevant increase in the distance covered at the 6MWT (p < 0.001) and a significant decrease in the discomfort of breathing in both activities (Borg scale of dyspnea ADL5, p = 0.008 and Borg scale of dyspnea of 6MWT, p = 0.004).

We also explored the relationship between NT-proBNP and the improvement in outcome measures of CR (change in meters and VO₂ at 6MWT and cumulative time of ADL). A weak, albeit statistically significant correlation, was found only between NT-proBNP and change in 6MWT distance (R = 0.2305, p = 0.036).

Finally, as the complaint of dyspnea seriously compromises the ability of patients to perform ADLs, we compared the mean cumulative value of the Borg scale before and after CR and found an overall symptom reduction (from 1.38 ± 1.31 to 1.13 ± 1.38; p = 0.006, Figure 2).

To our knowledge, this is the first study showing that, in elderly chronic HF patients, a short-term residential CR program improves the capacity to perform ADLs.

We extended our analysis to HF severity (NYHA class) and to those patients with reduced and preserved EF; NYHA 2 elderly HF patients were more sensible to CR program, even though 6MWT was improved in both subgroups (i.e., NYHA class 2 and 3), while HF elderly patients with reduced EF and those with preserved EF had a comparable behaviour in cardiometabolic response after CR.

As advancing age accelerates the functional impairment that characterizes HF, many elderly chronic HF patients also experience a decline in the ADLs, which contributes to loss of independence and worsens quality of life (Dunlay et al., 2015). Although the ability to perform ADLs is an important patient-related outcome, very few studies focused at their improvement. Gary et al. (2011) assessed the effects of a 12-week home-based exercise program on the time required for dressing, kitchen, household activities, and endurance walking in a sample of 24 patients with NYHA class 2 or 3 systolic HF between the ages of 40 and 75 years. The participants in the exercise group improved their time in seconds compared to baseline for completing most tasks and increased weight carried, while there were no changes in the control group. In the recent REHAB-HF trial, a progressive rehabilitation intervention initiated during hospitalization for HF and continued for 36 outpatient sessions improved physical function domains as assessed by the Short Physical Performance Battery (Kitzman et al., 2021).

At variance with the quoted studies, duration of intervention in our study did not exceed 25 sessions (mean length of stay 19 days), but is it worth to underscore that exercise was just one of the components of our comprehensive rehabilitation program.

A relevant question is whether these improvements had to be ascribed to the exercise training alone or whether other components of the rehabilitation intervention also concurred to the observed benefits. Theoretically, according to literature data showing an improvement in functional capacity and cardiopulmonary parameters in patients with HF (Giallauria et al., 2020; Malfatto et al., 2020; Dos Santos et al., 2021), we cannot dismiss the possibility that the optimization of pharmacological treatment might also have played a role. However, we have to underscore that, in our study, changes in therapy concerned a very limited number of patients over a limited number of days.

Elderly chronic heart failure who are engaged in a short-term residential cardiac rehabilitation program improve the performance of routine ADLs.

There is a need for further studies to identify and evaluate the efficacy of innovative treatments targeting improvement in ADLs as a strategy to improve clinical and patient-reported outcomes in elderly patients with chronic HF.

Anonimyzed data and materials will be made publicly available at: https://www.zenodo.org.

The studies involving human participants were reviewed and approved by ICS Maugeri Ethical Committee (EC n. 2204, date 29/05/2018). The patients/participants provided their written informed consent to participate in this study.

MTLR, SS, and PA contributed to the conception and design of research. MP, RR, AM, and ML conducted the experimental sessions. RM performed the statistical analysis. MP, MTLR, SS, and UC interpreted the results. MP and MTLR drafted the manuscript. MP, SS, UC, PA, and MTLR edited and revised critically the manuscript. All authors contributed to the article and approved the submitted version.

This work was supported by the “Ricerca Corrente” Funding scheme of the Ministry of Health, Italy.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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