Michel Terbraak

Cardiovascular diseases (CVD) are the leading cause of death worldwide. The most common form is coronary heart disease (CHD), which occurs when the vessels that supply the heart with blood become narrowed or blocked. Other frequent types of CVD include heart valve disorders and irregular heart rhythms (e.g. atrial fibrillation). These disorders can reduce the heart’s ability to pump blood effectively, leading to heart failure. Because of unhealthy lifestyles and an ageing population, the global burden of CVD has nearly doubled over the past 30 years, not only in terms of mortality but also in disability.

Older adults bear the highest burden of CVD and face different challenges compared to younger patients. When hospitalized for heart-related conditions, they are particularly at risk of physical decline and loss of independence. In addition, age-related syndromes such as frailty, including malnutrition, impaired balance, and cognitive decline, can hinder recovery. Despite the clinical relevance of these geriatric conditions, hospitals do not routinely screen for them. As a result, older adults at risk of functional decline after discharge are often not identified in time, and appropriate aftercare is lacking.

Transitional care interventions have been developed to improve continuity of care and patient outcomes. However, although these interventions have shown effectiveness in general older populations, these interventions often lack disease-specific components tailored to the needs of patients with CVD.

Although current guidelines recommend cardiac rehabilitation (CR) as part of standard aftercare following hospitalization for cardiovascular disease (CVD), participation among older adults remains unacceptably low. CR aims to promote long-term recovery, improve quality of life and physical capacity, reduce recurrent cardiac events, and prevent disability. However, most programs do not sufficiently account for geriatric syndromes, frailty, and comorbidity, making them less appropriate for older patients. Moreover, most CR programs are center-based, and transportation barriers further limit access for older adults. As a result, fewer than 30% of older adults enroll in CR programs, with participation dropping below 10% among those aged 80 and above.

As currently implemented, CR programs are not designed to address the complex, multidimensional needs of frail older adults. Moreover, evidence on effective and feasible adaptations of CR for this population remains limited, highlighting an urgent gap in clinical practice and research.

Physiotherapists play a central role in CR by conducting exercise tests, prescribing training programs, providing physical activity counseling, and supporting patients in adopting an active lifestyle. However, for frail older adults, physiotherapeutic care requires adaptations beyond traditional CR. First, physiotherapists must not only focus on conventional CR goals but also address geriatric syndromes such as frailty, balance impairments, and comorbidity. Yet, there is limited guidance on how to effectively integrate these domains into a single treatment plan. Second, to improve accessibility for this population, CR should be offered in a home-based format. Despite growing interest, such tailored, physiotherapist-led home-based programs for frail older adults with CVD remain underdeveloped.

To improve the aftercare of older adults after a hospitalization for CVD, in Amsterdam UMC we developed the Cardiac Care Bridge-intervention. This intervention combined transitional care with cardiac disease management, and incorporated a home-based CR component. This thesis aims to develop, test, and refine a physiotherapist-led, home-based cardiac rehabilitation approach tailored to frail older adults with CVD, embedded within the broader Cardiac Care Bridge transitional care intervention.

The thesis starts with a general introduction outlining the background and research questions that guided the development of physiotherapist-led home-based cardiac rehabilitation (Chapter 1). The following chapters reflect the stepwise development of the home-based CR component. We began by exploring its feasibility and content, based on physiotherapists’ experiences with delivering home-based CR to frail older adults in the Cardiac Care Bridge intervention (Chapter 2). We then evaluated patient participation by analyzing adherence and identifying factors that influenced engagement (Chapter 3), and assessed the effectiveness of the intervention on physical functioning using secondary data from the randomized controlled trial (Chapter 4).

Because physical activity counseling and exercise testing, two core components of cardiac rehabilitation, remain insufficiently adapted for older, frail patients with CVD, we addressed both gaps in the next part of this thesis. Using data from the Hospital-ADL cohort study, we monitored older adults during the first week after hospital discharge with Fitbit wearable devices, and evaluated whether their activity levels were associated with recovery of physical functioning after three months (Chapter 5).

We also validated the Two-Minute Step Test (2MST) as a home-based measure of cardio-respiratory fitness (VO2-peak) in older adults. Its performance was compared with the gold-standard cardiopulmonary exercise test (CPET) in patients who had undergone transcatheter aortic valve implantation (TAVI), a typically older and frail population (Chapter 6).

Finally, we developed expert-based recommendations to guide the tailoring of home-based CR to the specific needs of this population (Chapter 7). The thesis concludes with a general discussion of the findings and their implications for clinical practice, education, and future research (Chapter 8). Together, these studies offer insight into the building blocks of an effective, feasible, and person-centered approach to cardiac rehabilitation for frail older adults.

The results described in chapter 2 show that physiotherapists working with frail older adults in the Cardiac Care Bridge intervention consider home-based CR feasible. However, the feasibility of home-based CR appeared to depend on many factors. First, the possibility of performing exercises depends on the patient’s home (for instance the presence of stairs) and the practical possibility of placing training tools in the home environment. Second, the patient needs to have a sufficient level of motivation, and the physiotherapist should use motivational strategies to encourage the patients. Third, the quality of the interdisciplinary collaboration between healthcare providers who monitor and address risks such as the risk of physical decline, hospital readmission, or mortality is also an important factor. Especially, since organizing communication between hospital and community-based professionals often poses a challenge.

In chapter 3, we examined adherence to home-based cardiac rehabilitation among frail older patients, with a mean age of over 80 years. Of those who were referred, 67% initiated the home-based intervention component. Older age and higher grip strength in men were associated with lower participation rates, possibly because the oldest patients had other priorities, and stronger older men perceived less need for rehabilitation. In contrast, no significant associations were found between comorbidity or lower physical capacity and participation. These findings suggest that neither frailty, comorbidity, nor reduced fitness levels should automatically be seen as reasons to withhold referral to home-based CR in this population.

Chapter 4 demonstrated that home-based CR, integrated into the transitional Cardiac Care Bridge intervention, was effective in improving physical functioning in a subset of frail older adults with CVD for whom complete follow-up data were available. Patients in the intervention group showed significantly greater improvements in physical functioning (measured with the Short Physical Performance Battery [SPPB], which assesses leg strength, balance, and gait speed) over the six months following their hospitalization. However, no between-group differences were observed for handgrip strength, cardiorespiratory fitness, or activities of daily living. These findings suggest that home-based CR can lead to clinically meaningful improvements in physically independent functioning, and support the importance of reaching frail older adults with this intervention.

In chapter 5, physical activity was identified as a key factor associated with recovery, which was defined as no deterioration in physical functioning, hospital readmission, or death. After hospital discharge, thresholds of 1,043 steps per day or 72 minutes of light-intensity activity per day were associated with better recovery outcomes in frail older adults. While these thresholds offer useful guidance for rehabilitation goals, prospective studies are needed to evaluate if these thresholds can be used to identify individuals at higher risk of poor recovery. Nevertheless, the findings highlight the importance of monitoring and optimizing daily activity during the recovery process after a hospitalization.

Chapter 6 confirmed the validity and reproducibility of the two-minute step test (2MST), supporting its use as a practical alternative to cardiopulmonary exercise testing (CPET). In patients who had undergone Transcatheter Aortic Valve Implantation (TAVI), the 2MST showed strong correlations with peak oxygen uptake (VO2-peak), indicating that the 2MST can validly measure cardiorespiratory fitness. We also found high correlations between the 2MST performed at the outpatient clinic and the 2MST at home, indicating that the 2MST is a reliable measurement which is not substantially influenced by the environment. Our results further demonstrated a minimal detectable change of 16 steps, which means that patients who improve by 16 steps have improved beyond measurement error. These findings support the value of the 2MST as a home-based alternative for evaluating cardiorespiratory fitness, particularly in patients with severely limited exercise capacity or in those unable or unwilling to undergo lab-based CPET.

In chapter 7, we conducted a three-round Delphi study with national experts in cardiac care, geriatrics, and rehabilitation to develop recommendations for tailoring home-based cardiac rehabilitation to the needs of frail older adults with CVD in the Netherlands. The findings were synthesized into a practical framework to support personalized rehabilitation, taking into account individual goals, preferences, and barriers to physical activity.

While shared decision-making in cardiac care has traditionally focused on medical treatments, our findings suggest it is equally relevant when determining the most appropriate form of CR, whether home-based, center-based, or otherwise. Older adults often prefer to rehabilitate at home and respond well to encouragement from caregivers, yet referral decisions are still frequently influenced by assumptions or logistical factors rather than by what patients themselves want. These findings highlight the need to actively incorporate patient preferences to improve participation in CR among older adults, which is key to expanding its benefits in the older population.

Chapter 8 discusses the main findings and presents implications for clinical practice, education, and future research, emphasizing the need to integrate personalized, home-based CR into standard care for frail older adults with CVD. These findings collectively support the implementation of personalized, home-based CR as a feasible and necessary extension of care, a treatment option that may improve outcomes, reduce healthcare costs, and increase participation among those currently not reached by traditional CR programs.