Shared decision making (SDM) facilitates delivery of medical therapies that are in alignment with patients' goals and values. Medicare national coverage decision for several interventions now includes SDM mandates, but few have been evaluated in nationwide studies. Based upon a detailed needs assessment with diverse stakeholders, we developed pamphlet and video patient decision aids (PtDAs) for implantable cardioverter/defibrillator (ICD) implantation, ICD replacement, and cardiac resynchronization therapy with defibrillation to help patients contemplate, forecast, and deliberate their options. These PtDAs are the foundation of the Multicenter Trial of a Shared Decision Support Intervention for Patients Offered Implantable Cardioverter-Defibrillators (DECIDE-ICD), a multicenter, randomized trial sponsored by the National Heart, Lung, and Blood Institute aimed at understanding the effectiveness and implementation of an SDM support intervention for patients considering ICDs. Finalization of a Medicare coverage decision mandating the inclusion of SDM for new ICD implantation occurred shortly after trial initiation, raising novel practical and statistical considerations for evaluating study end points. METHODS/DESIGN: A stepped-wedge randomized controlled trial was designed, guided by the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) planning and evaluation framework using an effectiveness-implementation hybrid type II design. Six electrophysiology programs from across the United States will participate. The primary effectiveness outcome is decision quality (defined by knowledge and values-treatment concordance). Patients with heart failure who are clinically eligible for an ICD are eligible for the study. Target enrollment is 900 participants. DISCUSSION: Study findings will provide a foundation for implementing decision support interventions, including PtDAs, with patients who have chronic progressive illness and are facing decisions involving invasive, preference-sensitive therapy options.