Aims: The major cardiovascular (CV) adverse effects observed with sipuleucel-T from large multi-institutional clinical trials included thromboembolic events, myocardial infarction, and congestive heart failure in up to 0.3% of patients with CV risk factors. The incidence, outcomes, and mechanisms in real-world clinical settings of these CV adverse effects to date have not been fully elucidated. Our study identified a patient with sipuleucel-T-induced inflammatory cardiomyopathy, which led to the identification of CV adverse effects associated with sipuleucel-T from a large pharmacovigilance database and elucidation of its potential mechanisms. Methods and results: Using the MedDRA term 'cardiac disorders' (System Organ Class level), CV adverse events associated with sipuleucel-T versus all other drugs were reviewed from VigiBase, a large pharmacovigilance database. Disproportionality analysis was calculated by the information component (IC), a Bayesian disproportionality indicator. A positive IC025 (IC 95% lower end credibility interval) value (>0) is the traditional threshold used in statistical signal detection at the Uppsala Monitoring Centre. From VigiBase, the total number of CV adverse drug reaction reported with sipuleucel-T was 306 out of a total of 22 980 104 adverse drug reactions in VigiBase on 10/25/2020. MedDRA preferred terms levels were grouped into major CV adverse drug reaction categories where we observed significant reports of myocardial ischaemia, supraventricular tachycardia (particularly atrial fibrillation/atrial flutter), congestive heart failure, and valvular disorders. Myocardial ischemia included acute myocardial infarction (IC025 2.3) with n = 4/26 (15%) of these individual case safety reports considered fatal. Among patients with 'cardiac failure congestive' (IC025 1.5), 11 of these 43 cases (26%) were fatal with 42 (98%) of these cases considered to be solely due to sipuleucel-T. Conclusions: Patients with CV risk factors who are receiving sipuleucel-T may be at higher risk for congestive heart failure, myocardial ischemia, and supraventricular tachycardia. Electrocardiograms during weekly sipuleucel-T infusions and left ventricular function monitoring with echocardiogram should be considered in these patients. Our findings are suggestive of another rare presentation of T-cell-mediated CV toxicity with cancer immunotherapy.