Background Mental distress is reported internationally among patients with cardiac disease. A Danish survey found that 25% of patients with cardiac disease experienced symptoms indicating anxiety and that anxiety was associated with an increased risk of death. Aim The aims of this study were to (1) compare cause of death patterns among deceased cardiac patients with anxiety to those without anxiety and (2) examine the association between anxiety symptoms and specific causes of death. Methods We used data from the DenHeart survey to evaluate symptoms of anxiety at discharge by using the Hospital Anxiety and Depression Scale. Data on mortality in the 3 years after discharge and cause of death according to International Classification of Diseases-10 classification came from national registers. Cause of death was compared between patients with and without anxiety using χ2 tests. The association between symptoms of anxiety and cause of death was investigated using logistic regression. Results Of 12 913 patients included, a total of 1030 (8%) died within 3 years. After 1 year, 4% of patients with anxiety symptoms had died versus 2% of patients without; after 3 years, the proportions were 9% versus 8%, respectively. Almost all died of natural causes irrespective of anxiety symptoms. No statistically significant differences were found regarding the cause of death between patients with and without anxiety. Conclusion Despite higher mortality rates in patients with cardiac disease with anxiety symptoms, the pattern of cause of death was identical for patients with cardiac disease with and without anxiety symptoms. It seems that an acceleration of morbid processes leading to mortality is more likely than a difference in cause of death. However, further research is needed to better understand the behavioral and pathophysiological processes that cause the higher mortality seen among patients reporting symptoms of anxiety.