Abstract Background/Introduction Following an acute cardiac event, individuals commonly face multiple emotional and mental health challenges. For many people, this change in their mental health will resolve over time. However, one in five will go on to develop major depressive disorder. The development of major depressive disorder is a complex co-morbidity that, if left unchecked, can increase the risk of subsequent cardiac events and mortality. Systems thinking methodology offers a novel approach to investigating factors that contribute to mental health following a cardiovascular event. Purpose This project aims to (1) unravel the complex system influencing mental health after a cardiac event and (2) pinpoint priorities for supporting individuals' mental well-being following a cardiac event. Methods Group model building workshops using Deakin University’s purpose-built STICKE software were conducted over Zoom to explore the interrelationships contributing to mental health following a cardiovascular event. Twelve participants, including consumers (n = 3) and healthcare professionals (n = 9) from across Australia, engaged in two 1.5-hour workshops. Guided by the prompt "Reflect on factors influencing a person’s mental health post-cardiac event", participants worked together to construct a systems diagram. This facilitated exploration, visual mapping, and identification of factors and priority areas influencing mental health post-cardiac event. The diagram was then analysed using the theoretical domains framework. Results The STICKE diagram developed demonstrates the interplay of various factors impacting mental health across the cardiac healthcare journey at both patient and system levels (see Figure 1). Using the theoretical domains framework, eight domains were identified: knowledge, skills of healthcare professionals, environmental context, personal context, emotional response to event and recovery, social influences, behavioural regulation, and beliefs about individual capacity. Knowledge (including health literacy and staff training), environmental context (addressing gaps in care and navigating the system), and social influences (such as social isolation) were domains that were consistently raised in the workshop (see Figure 2). Stakeholders also identified the following key priority areas: highlighting the need for additional support for staff and intervention to increase health literacy and knowledge around mental health. Conclusion(s) Supporting mental health post-cardiac events is a multifaceted challenge requiring a comprehensive community-level intervention, particularly in the initial weeks post-hospitalisation. The insights gained from this study will inform the co-design of an intervention aimed at increasing health literacy and knowledge around mental health following a cardiovascular event.