While early symptoms of anxiety and depression resolve for many patients soon after an acute cardiac event, the persistence or worsening of symptoms indicates increased mortality risk. It is therefore important to identify the predictors, or red flags, of persistent or worsening anxiety and depression symptoms. Most previous research has focussed on metropolitan patients, hence the need for studies of regional and rural dwellers. Method: In this study, 160 cardiac patients consecutively admitted to two hospitals in regional Victoria, Australia, were interviewed in hospital and 2 and 6 months after discharge. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale. Growth mixture modelling was used to identify the trajectories of anxiety and depression over the 6 months after the acute event, and post-hoc tests identified predictors of persistent or worsening symptoms. Results: For both anxiety and depression, three common symptom trajectories were identified. Inhospital anxiety symptoms tended to persist over time, whereas inhospital depression symptoms resolved for some patients and worsened for others. A mental health history, younger age, smoking, financial stress, poor self-rated health, and social isolation were red flags for persistent anxiety and worsening depression. Additionally, diabetes, and other comorbidities were red flags for persistent anxiety. Conclusions: The results highlight several potential red flags for increased risk of persistent anxiety or worsening depressive symptoms after a cardiac event, including demographic, psychosocial, and behavioural indicators. These red flags could assist with identification of at-risk patients on admission to or discharge from hospital, thereby enabling targeting of interventions.