Heart failure (HF) is a complex, heterogeneous, increasingly prevalent cardiovascular disorder with high morbidity and mortality [
1,
2]. Self-care behaviors are essential for the effective treatment of heart failure, and poor self-care may lead to adverse clinical events in patients with HF, including repeated hospitalizations, poor quality of life, and increased mortality [
3]. Several factors contribute to adequacy of self-care. Depression [
4], sleep disturbances [
5], impaired cognition, multiple comorbid conditions [
6], and low level of awareness of illness decline all limit self-care [
7]. The involvement of the partner, i.e., the informal caregiver who assists the patient with daily self-care, is crucial. Caregiver mental health, strain, and contributions to self-care predict patient clinical events in heart failure [
8,
9,
10]. A caregiver is often someone very close to the patient, such as a spouse or an adult child, who helps the patient with daily functioning and has the potential to influence the trajectory of this chronic disease. Increasingly, researchers are using a dyadic approach to study self-care in HF because they have realized that self-care is a dyadic phenomenon in which patients and their caregivers are an interdependent team working within their life context and that the way they appraise illness as a team influences management of the disorder [
11]. HF patients usually have a partner with whom they make day-to-day decisions about symptom management but also about diet and how to deal with worsening symptoms. Dyadic HF research has shown that good relationships with a partner and other people [
12,
13], knowledge regarding HF of each member of the dyad [
14], congruence in symptom assessment, and agreement on who is providing self-care [
15] influence HF behavior and may determine a patient’s outcome. Within this dyad, caregivers influence patient self-care and patients influence caregiver’s contribution to self-care. Patients struggle to perform self-care; therefore, the contribution of informal caregivers is fundamental, and a dyadic approach is necessary. Therefore, the dyadic approach to self-care allows a more accurate assessment the factors determining effective self-care in HF by including both the patient and the caregiver [
16].
Studies conducted on caregiver participation in self-care in HF and other chronic conditions have shown that taking the caregiver role into account improves patient outcomes. Since HF patients and their caregivers influence each other in self-care, investigators have started to approach self-care studies using dyadic approaches because they allow controlling for the interdependence between patients and caregivers. The theoretical framework for research on dyadic care in HF is a combination of three theories: the Theory of Dyadic Illness Management (TDIM) [
11], Situation-Specific Theory of Heart Failure Self-Care (SSTHFSC) [
17,
18], and the Situation-Specific Theory of Caregiver Contribution to Heart Failure Self-Care (SSTCCHFSC) [
19]. The TDIM illustrates that management of disease is a dyadic process and describes the interdependency of the patient and the caregiver. The Situation-Specific Theory of Heart Failure Self-Care illustrates the unique aspects of self-care in patients with HF. The Situation-Specific Theory of Caregiver Contribution to Heart Failure Self-Care describes factors influencing caregiver contribution to HF self-care as well as outcomes of this contribution. Research on dyadic self-care in HF focuses on the joint management of this specific disease by the adult patient and caregiver. Many previous studies of self-care in HF have focused on either the patient [
20,
21,
22,
23] or the caregiver [
9,
24,
25]. There are also studies investigating dyads with chronic illnesses, but their focus was more about dyadic appraisal and coping (i.e., spousal involvement and communication between dyadic partners) [
26]. A dyadic approach to the care of a patient with HF emphasizes the joint efforts of both members in coping with the disease and the interdependency of the two members of the dyad on effectiveness of HF self-care.
HF is a heterogeneous disease, both in terms of patient health status as well as caregiver experience and tasks. The time required in HF caregiving is highly variable and depends on several factors, including the severity and stability of HF, the presence of comorbidities, impairments to physical and/or cognitive function, the complexity of the treatment regimen, and other situational aspects [
27]. During the disease, as the disease advances, the experience of HF becomes characterized by continuous management of progressive and pervasive symptoms (e.g., dyspnea, fatigue, edema, insomnia) that severely compromise the quality of life [
18,
28]. Additionally, patients with advanced heart failure have an uncertain disease trajectory, and this places a significant burden on heart failure caregivers [
29]. Higher levels of comorbid conditions are associated with family caregivers feeling fewer positive feelings about providing care [
30], and higher patient with HF functional class (worse symptom severity) is significantly associated with greater caregiver anxiety and general stress [
31]. Studies across caregiving contexts suggest that caregivers of patients with more severe illness may need the most support [
32,
33,
34].