There is growing evidence for the development of posttraumatic stress symptoms as a consequence of acute cardiac events. Acute coronary syndrome (ACS) patients experience a range of acute cardiac symptoms, and these may cluster together in specific patterns. The objectives of this study were to establish distinct symptom clusters in ACS patients, and to investigate whether the experience of different types of symptom clusters are associated with posttraumatic symptom intensity at six months. ACS patients were interviewed in hospital within 48 h of admission, 294 patients provided information on symptoms before hospitalisation, and cluster analysis was used to identify patterns. Posttraumatic stress symptoms were assessed in 156 patients at six months. Three symptom clusters were identified; pain symptoms, diffuse symptoms and symptoms of dyspnea. In multiple regression analyses, adjusting for sociodemographic, clinical and psychological factors, the pain symptoms cluster (β = .153, P = .044) emerged as a significant predictor of posttraumatic symptom severity at six months. A marginally significant association was observed between symptoms of dyspnea and reduced intrusive symptoms at six months (β = -.156, P = .061). Findings suggest acute ACS symptoms occur in distinct clusters, which may have distinctive effects on intensity of subsequent posttraumatic symptoms. Since posttraumatic stress is associated with adverse outcomes, identifying patients at risk based on their symptom experience during ACS may be useful in targeting interventions.