Background: High rates of readmission after myocardial infarction and cardiac surgery have been reported, indicating a heavy burden for both patients and society. Patient-reported outcomes are predictors of adverse outcomes such as morbidity and mortality and may also be useful in preventive risk assessment as predictors of readmission. Aim: To describe (i) the prevalence of cardiac readmissions one year after hospital discharge among cardiac patients, (ii) patient-reported outcomes at hospital discharge as predictors of readmission. Methods: The following patient-reported outcomes were measured across cardiac diagnoses at hospital discharge from the five heart centres, cardiology and thoracic surgery units, as a part of the national, cross-sectional DenHeart Study: Short-Form 12 (SF-12), Hospital Anxiety and Depression Scale (HADS), EuroQoL (EQ-5D-5L), HeartQoL and the Edmonton Symptom Assessment Scale (ESAS). One year readmissions were obtained from national registers. Results: A total of 34,564 cardiac patients were discharged of whom 16,712 patients completed the questionnaire. A total of 11,693 (36%) patients were readmitted for cardiac reasons at least once during the first year after index admission. The risk of readmission was predicted by anxiety (HR = 1.36 (CI:1.26–1.46)) and depression (HR = 1.42 (CI:1.31–1.55)). Higher scores reflected lower readmission risk on the physical (HR = 0.98 (CI:0.98–0.98)) health component of the SF-12. Conclusion: A total of 36% of cardiac patients admitted to a national heart center were readmitted during the first year. Readmission was predicted by patient-reported anxiety, depression, perceived health, quality of life and symptom distress, which may be used in risk assessment in clinical practice.