Post–Myocardial Infarction Scar With Fat Deposition Shows Specific Electrophysiological Properties and Worse Outcome After Ventricular Tachycardia Ablation

Background Fat deposition ( FD ) is part of the healing process after myocardial infarction. The characteristics of FD and its impact on the outcome in patients undergoing ventricular tachycardia ( VT ) ablation have not been thoroughly studied. Methods and Results We studied consecutive patients undergoing post–myocardial infarction VT ablation with pre‐procedural cardiac computed tomography. FD was defined as intra‐myocardial attenuation ≤ −30  HU on computed tomography. Clinical, anatomical, and post‐procedural outcome was assessed in the overall population. Electrophysiological characteristics were assessed is a subgroup of patients with high‐density electro‐anatomical maps. Sixty‐nine patients were included (66±12 years). FD was detected in 44 (64%) patients. The presence of FD related to scar age (odds ratio [OR]: 1.14 per year; P =0.001) and scar extent ( OR : 1.27 per segment; P =0.02). On electro‐anatomical maps, FD was characterized by lower bipolar amplitude ( P <0.001) and prolonged electrogram duration ( P <0.001). Although the proportion of local abnormal ventricular activation was similar ( P =0.22), local abnormal ventricular activation showed lower amplitude ( P <0.001) and were more delayed ( P <0.001) in scars with FD . After a mean follow‐up of 26 months, patients with FD experienced a worse outcome including all‐cause mortality and VT recurrence (70% versus 28%, P log rank=0.009). On multivariate analysis, FD (hazard ratio=2.69; 95% CI , 1.12–6.46; P =0.027) and left ventricular systolic dysfunction (hazard ratio=2.57; 95% CI , 1.13–5.85; P =0.024) were independent predictors of adverse outcomes. Conclusions FD in patients with post–myocardial infarction VT undergoing catheter ablation relates to scar age and size and may be a marker of adverse outcomes including all‐cause mortality and VT recurrence.