Cardiovascular diseases (CVDs) are a major global health challenge, compounded by a significant systemic treatment gap: the underutilization of cardiac rehabilitation (CR). Central to this issue is the crucial yet underperforming referral process to CR due to various factors, including patients’ lack of information. By co-designing a CR referral assistant with cardiac patients and healthcare professionals, this work explores how technology can support patient journeys from the acute hospital to CR, overcoming existing healthcare system barriers. This work (1) contributes a map of patients’ evolving needs tailored to their pathway, (2) provides design implications for interactive digital health technologies aiming to facilitate patient transitions across established healthcare system boundaries, and (3) discusses the potential of technology as a “patient companion” during their transition to CR.