Generalized anxiety disorder (GAD) is a significant yet modifiable risk factor for worse cardiovascular disease (CVD) outcomes. The treatment of GAD in an accessible manner represents an unmet need in CVD, given that patients with CVD experience numerous barriers to in-person treatment engagement. This paper presents the rationale and design for an investigation of a strategy to enhance care for patients with CVD by introducing a scalable, affordable, and system-friendly digital intervention that targets a prominent modifiable risk factor (generalized anxiety and associated worry) for negative health behaviors in CVD. In the context of a randomized clinical trial design, we describe an experimental medicine approach for evaluating the degree to which a digital cognitive behavior therapy (dCBT), relative to a waitlist control group, engages anxiety and worry outcomes in a sample of 90 adults who have experienced an acute CVD event and who have comorbid GAD symptoms. We also investigate the degree to which dCBT leads to greater changes in GAD symptoms compared to the control condition and whether reductions in these symptoms are associated with corresponding reductions in cardiac anxiety and cardiac health behaviors (including smoking, physical activity, heart-healthy diet, and medication adherence). We propose that by targeting GAD symptoms in CVD in a way that does not tax ongoing medical care provision, we have the potential to improve the uptake of effective care and address both GAD and associated health behaviors.