1. A method for determining an optimal output of an ablation catheter ( 22 ) for a myocardial ablation in a patient, with the following steps: Creation of at least one at least three-dimensional image recording of an ablation region provided for the myocardial ablation using at least one image recording apparatus ( 16 ) (a), At least partial segmentation of the recorded ablation region to obtain segmentation information using a computation apparatus ( 17 ) (b), At least partial determination from the segmentation information of the location-dependent thickness of the myocardium ( 8 ) in the ablation region by the computation apparatus (c) and Determination of the optimal output of the ablation catheter ( 22 ), in particular by the computation apparatus ( 17 ) or a separate computation apparatus ( 20 ) of an ablation catheter system ( 21 ), as a function of the determined myocardium thickness (d).