An Application of SMART Methodology to Optimize an Intervention to Maintain Improvements in Health Behaviors in Under-resourced Patients after Phase II Cardiac Rehabilitation - PROJECT SUMMARY/ABSTRACT Cardiovascular disease (CVD) is the leading cause of death in the United States. Cardiac rehabilitation (CR) is an evidence-based, cost-effective, and widely available multidisciplinary program that combines supervised exercise with psychoeducation on health behavior change aimed at improving overall health and reducing cardiovascular risk in individuals with established CVD. However, under-resourced and underserved CVD patients (e.g., women, racial and ethnic minorities, low socioeconomic status, disabled) are less likely to maintain their adherence to key cardioprotective behaviors (weight management, physical activity [PA], and medication adherence) after CR and are under-represented in post-CR research; these factors combined increase the health disparities in CVD care that these sub-populations experience, especially since many cannot complete self-pay Phase III maintenance programs. In the PI’s previous work, under-resourced and under-represented patients indicated that they want technology-based maintenance support interventions that utilize technology they already own, are minimal burden, offer a flexible schedule, offer more support for patient needs without overwhelming them with program requirements before demonstrating that a lower level of support was insufficient, and produce desired results. Patients felt resistant to initiating a demanding, time- intensive, or in-person maintenance intervention immediately following CR. The present application utilizes a Sequential, Multiple Assignment, Randomized Trial (SMART) design to create a stepped care model that adapts to patient needs and minimizes patient burden. Participants (N=400) will be randomized to receive either a low-intensity text messaging intervention or an automated online program for 2 months and determine which produces superior adherence (Aim 1). Following classification as intervention responders or non- responders, responders will continue receiving their initial low-intensity intervention. We will then determine whether low- or high-intensity home-based CR (with or without case management) for 3 months produces better behavioral adherence following failure of a low-intensity intervention failure (Aim 2). We will then finalize the ideal adaptive intervention based on Aims 1 and 2 results and moderator analyses (Aim 3). Patients will complete post-intervention assessments at 6 months and exploratory outcomes assessment (death, rehospitalization, quality of life). This research will result in a stepped care model for under-resourced patients’ behavioral adherence maintenance following CR. This project advances the science of CVD treatment and post-CR care, and it will directly impact CVD patient outcomes by extending the benefits of evidence-based, effective care as well as target health disparities among less-resourced CVD patients.