We describe catheter ablation of recurrent ventricular tachycardia using high-resolution definition of a myocardial infarct scar by contrast-enhanced cardiac computed tomography (CT). Positron emission tomography scanning as well as three-dimensional electroanatomic mapping confirmed the extent of scar prior to ablation. Catheter ablation based on substrate mapping was successful in eliminating the ventricular tachycardia. Detection of scar by cardiac CT has the potential to abbreviate voltage/substrate mapping in the electrophysiology laboratory. To our knowledge, this is the first time myocardial scar was defined by cardiac CT and utilized for defining an ablation strategy for ventricular tachycardia.