BACKGROUND: A high proportion of cardiac patients suffers from depression, which is an antecedent for suicidal ideation. This study identifies clinical vulnerabilities for suicidal ideation in cardiac patients. METHODS: The primary outcome of the study was severity of suicidal ideation as measured with the Patient Health Questionnaire (PHQ-9) item No. 9. Covariates were demographics, cardiac characteristics (i.e., Canadian Cardiovascular Society angina rating of chest pain and New York Heart Association rating of shortness of breath), depression (PHQ-8,i.e., PHQ-9 minus item No. 9), anxiety (Generalized Anxiety Disorder-7, GAD-7), somatic symptoms (PHQ-15), illness perception (Brief-Illness Perception Questionnaire), and health-related quality of life (EuroQol-5D, EQ 5D). RESULTS: Data from 1,976 patients were analysed. At least 14% (95% CI [12%, 16%]) of patients indicated suicidal ideations within the last 2 weeks. Bivariate analyses yielded associations between suicidal ideation and higher levels of depression severity, anxiety severity, somatic symptom burden, chest pain, shortness of breath, negative illness perceptions, reduced health-related quality of life, and a higher probability of living alone (all p < 0.001). A multivariable ordinal regression revealed depression severity and anxiety severity to show the highest associations with suicidal ideation (OR  = 1.22, p < 0.001; OR  = 1.09, p < 0.001). Having a defibrillator implant was associated with a lower probability of suicidal ideation (OR = 0.27, p = 0.017). CONCLUSIONS: This study identified several clinical vulnerabilities of suicidal ideation. The results stress the importance of screening for suicidal ideation in clinical practice.