We demonstrated a 47 year-old woman with ischemic-VT with repetitive ICD-shocks, requiring ablation. Pre-procedural CT demonstrated a single anatomical channel on the inferior-basal infarcted area between <3mm wall thinning area and the mitral annulus, which suggested the circuit of two VTs observed. Additionally, distribution of <2mm and <3mm scars can explain the mechanism of the variation of QRS morphology and S-QRS interval during entrainment. Ablation on this region resulted in no VT- inducibility and absence of any VTs for 2yrs. CT wall thinning data may allow us to understand the mechanism and circuit of VT and aid VT ablation procedures.