Does cardiac phenotype shape the impact of motivational interviewing on caregiver contribution to self-care? A secondary analysis of the MOTIVATE-HF trial

Abstract Background Heart Failure (HF) is commonly classified into three phenotypes based on left ventricular ejection fraction (EF): HF with reduced EF (HFrEF), HF with mildly reduced EF (EFmrEF), and HF with preserved EF (HFpEF). These phenotypes differ in clinical complexity and response to treatment, with HFpEF generally characterized by greater complexity and lower pharmacological effectiveness. As a result, patients with HFpEF often present with greater clinical complexity, and pharmacological treatments are generally less effective. Previous findings from the MOTIVATE-HF trial showed that the effects of motivational interviewing (MI) - a counseling approach aimed at enhancing HF self-care - were moderated by EF, with patients with HFpEF deriving less benefit. Whether EF similarly moderates the effects of MI on caregiver contribution to self-care maintenance, self-care management, and caregiver confidence remains unknown. Caregiver contribution to HF self-care has been associated with improved patient outcomes. Purpose To examine whether EF moderates the effects of MI on caregiver contribution to self-care maintenance, management, and caregiver confidence over time. Methods This secondary analysis used data from the MOTIVATE-HF randomized controlled trial. Patient–caregiver dyads were allocated to usual care, MI delivered to the patient only, or MI delivered to both the patient and the caregiver. Caregiver contribution to self-care maintenance, management, and confidence was assessed at baseline and at four follow-up time points over 12 months. Population-averaged generalized estimating equation models were fitted separately for each domain, with adjustment for baseline scores. EF was modeled as a continuous moderator, and three-way interactions between group, time, and EF were tested. Estimated marginal means were used to illustrate longitudinal patterns across EF levels. Results A total of 510 caregivers were included (mean age 53 years, SD 15; 74% female). EF did not moderate the effects of MI on caregiver contribution to self-care maintenance, which remained largely stable over time and was predominantly predicted by baseline levels. In contrast, EF significantly moderated MI effects on caregiver contribution to self-care management and caregiver confidence. For both domains, MI effects were stronger and more sustained at lower EF levels, particularly when MI was delivered to both patients and caregivers, and progressively attenuated as EF increased. Conclusions EF, as a marker of HF phenotype, plays a key moderating role in caregivers’ responsiveness to motivational interviewing for HF symptom management and caregiver confidence. MI-based caregiver interventions may therefore need to be tailored according to HF phenotype, with caregivers of patients with EFmrEF and HFpEF likely requiring more intensive or targeted support strategies to enhance their contribution to patient self-care.