Advancing translational research in digital cardiac rehabilitation: The preparation phase of the Multiphase Optimization Strategy.

While digital cardiac rehabilitation (CR) is an effective alternative to center-based CR, its components and mechanisms of change remain poorly understood. The Multiphase Optimization Strategy (MOST) provides a framework that allows the effects of individual components of complex interventions to be studied. There is limited guidance within MOST on how to develop a conceptual model. This article describes the development of a conceptual model of digital CR. The conceptual model was developed based on several strands of evidence: (i) a systematic review of 25 randomized controlled trials to identify the behavior change techniques in digital CR interventions, (ii) a qualitative study of patients' (n = 11) perceptions of the mechanisms of digital CR, and (iii) a review of international guidelines. Tools and frameworks from behavioral science, including the Behaviour Change Wheel, Capability, Opportunity, Motivation and Behavior model, and Theoretical Domains Framework were used to integrate the findings. An initial conceptual model of digital CR was developed and then refined through discussion. The conceptual model outlines the causal process through which digital CR can enhance outcomes for patients with cardiovascular disease. The model illustrates the key intervention components (e.g. goal setting and self-monitoring, education, exercise training), targeted outcomes (e.g. physical activity, healthy eating, medication adherence), and theorized mediating variables (e.g. knowledge, beliefs about capability). The article provides an example of how behavioral science frameworks and tools can inform the preparation phase of MOST. The developed conceptual model of digital CR will inform guide decision-making in a future optimization trial.