Among older adults, heart valve disease is common and often requires treatment with valve repair or replacement. What used to require open heart surgery can now be done with less invasive transcatheter heart valve interventions (THVIs), allowing for less morbidity and quicker recovery. However, despite the safety and procedural success of THVIs, over one-half of patients are dead, have poor quality of life (QoL), and/or are hospitalized 1 year after a THVI. Cardiac rehabilitation (CR) effectively mitigates these poor outcomes in patients with cardiovascular disease, including those undergoing heart valve procedures. However, among Medicare beneficiaries, only 25% of those undergoing a THVI participate in center-based CR (CBCR), which highlights a significant unmet clinical need. To address this need, our long-term goal is to develop a home- based CR (HBCR) program that extends the benefits of CR to more individuals after THVIs. Our over-arching hypothesis is that a HBCR mobile health intervention that innovatively addresses key target health behaviors will reduce clinical events and improve physical activity, functional capacity, and QoL after THVIs and that an interactive delivery and longer duration of the active intervention will produce greater benefits. We propose a multicenter randomized controlled trial enrolling 375 patients undergoing aortic or mitral THVIs who do not intend to participate in CBCR; those who intend to pursue CBCR will be followed in a registry. Participants will be assigned to 3 groups: control (1) vs. a HBCR mobile health intervention with hands-off (2) vs. interactive (3) delivery. The intervention addresses key target health behaviors and includes Apple Watch (to encourage physical activity and give reminders on healthy living) and an exercise prescription (to build strength/balance). The hands-off and interactive delivery groups receive the same intervention, except for a video call (every other week) with an exercise physiologist (interactive group only). Each intervention group (hands-off, interactive) will be randomized to 12-week vs. 24-week duration of the active intervention. The co-primary endpoints are: (1) clinical events composite (death, rehospitalization, skilled nursing facility visits); and (2) average daily total activity counts. Key secondary endpoints: amount, intensity, consistency of physical activity; 6-minute walk distance; and QoL. We test whether the HBCR mobile health intervention (compared to control) reduces clinical events and improves physical activity, function capacity, and QoL after THVI (Aim 1) and whether interactive vs. hands-ff delivery (Aim 2) or 24-week vs. 12-week active duration (Aim 3) of the intervention yields greater benefits. We also explore mediators of clinical benefit and mechanisms of behavior change. With population aging, prevalence of heart valve disease and number of THVIs are rapidly increasing. Overcoming disablement associated with severe valve disease requires m...