The number of patients with implanted left ventricular assist devices is constantly increasing. Numerous patients suffer from drug-resistant ventricular tachycardias. Only a few studies and reports about ablation therapy in this cohort of patients are available. Electromagnetic interferences between the left ventricular assist device and the three-dimensional mapping system which is used for ablation has been described as disabling the investigator to create a proper map of the left ventricle. We observed that this interference is interrupted by "hot mapping" meaning that one pretends an ablation with only 5 W, permitting the creation of a clear map in areas of interference.