MIGHTIER: Movement in Heart Transplant patients: the Impact of Environmental factoRs

PROJECT SUMMARY/ABSTRACT Long term survival of pediatric heart transplant (HT) patients remains unacceptably low and is driven in part by modifiable cardiovascular risk factors. Children with HT engage in low levels of moderate to vigorous physical activity (MVPA), which is a major health problem for a population already at increased cardiovascular risk and

further contributes to their morbidity and mortality. Increasing MVPA may be a critical way to improve cardiovascular health, quality of life, and survival in this population. While environmental exposures are associated with physical activity in children without HT, their effects in those with HT are unknown, and likely

different. To design effective, equitable, generalizable, and sustainable interventions to increase MVPA, we need to recognize the environmental determinants of MVPA and involve stakeholders in intervention development. Jonathan Edelson, MD, is a pediatric cardiologist and physician-scientist passionate about

understanding how physical activity can improve outcomes of children after HT. With a mentoring team specializing in implementation science, Dr. Edelson will 1) develop expertise in mobile health technology and accelerometry; 2) hone the skills to design, launch, oversee, and complete a multisite, prospective

interventional study; and 3) gain methodologic expertise in geospatial and qualitative methodology. This study proposes to leverage Dr. Edelson's existing mobile health studies of pediatric HT patients to evaluate the macro and micro environmental determinants of MVPA in pediatric HT and to pilot an exercise intervention

using the Multiphase Optimization Strategy (MOST). Specific Aims are to 1) Determine the association of the macro-environment with MVPA in a socioeconomically diverse cohort of children after HT; 2) Use qualitative methodology to identify micro-environmental determinants of participation in physical activity in pediatric HT

patients; 3) Determine the feasibility and preliminary efficacy of a digital exercise program in pediatric HT patients. Dr. Edelson will map participant addresses to neighborhood-level built and natural environmental exposures to estimate the association of MVPA patterns with macro environmental factors. He will then

conduct semi-structured interviews informed by the COM-B (Capability, Opportunity, Motivation, Behavior) implementation science framework with patients and their families to identify determinants of physical activity and desirable components of a mobile health exercise intervention. Finally, he will apply the knowledge gained

to the development and implementation of a prospective pilot longitudinal exercise intervention using MOST, a strategy for developing multi-component intervention which has successfully informed physical activity interventions. This K23 award will support Dr. Edelson's pathway to becoming an independent investigator in

the interventional space with skills that will support future R level proposals using exercise in a large multisite cohort to improve long-term outcomes. This work will provide a novel framework for exercise interventions that will be applicable to a range of populations, further highlighting the public health significance of this proposal.