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

Abstract

BackgroundFat 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 ResultsWe 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.

Association of left ventricular tissue heterogeneity and intramyocardial fat on computed tomography with ventricular arrhythmias in ischemic cardiomyopathy

“… 13 The amount of infiltrating fat was also a predictor of VT recurrence after VT ablation in ICM patients. 14 Unlike these studies, our cohort consists of ICM patients with LV systolic dysfunction without any previous VT and thus is more representative of a broader ICM population at high risk for VAs. Our results show a lack of association between total intramyocardial fat mass and arrhythmic outcomes.…”

“…Additionally, although intramyocardial fat is recognized to develop progressively after myocardial infarction and may be arrhythmogenic, no studies have examined the relationship between intramyocardial fat mass on CE-CT and the occurrence of VAs in a cohort of ICM patients with LV systolic dysfunction and no previous VAs. 8 , 9 , 10 , 11 , 12 , 13 , 14 …”

Recurrent ventricular tachycardia associated with lipomatous metaplasia of a myocardial scar

“…In a recent study involving a group of 72 patients undergoing ablation for VT, fat deposition within the myocardium was associated with worse outcomes and higher rates of VT recurrence. 12 Further strategies must be implemented before proceeding with invasive procedures in this patient population. Future implications may suggest broader and earlier use of CMR to evaluate the presence of lipomatous metaplasia in post-myocardial infarction scars and better risk stratification of patients prior to ablation to predict propensity for VT and mortality.…”

Cardiac Adiposity and Arrhythmias: The Role of Imaging

“…An association between lipomatus metaplasia and abnormal ventricular electrophysiology has been reported in both animal and clinical studies [ 110 , 128 ]. In this regard, electrophysiological studies demonstrated that lipomatus metaplasia, as depicted by CMR or CT, was strongly associated with scar age and size, lower bipolar and unipolar amplitudes and critical ventricular tachycardia circuit sites in patients with ischemic cardiomyopathy, suggesting its potential role in the generation of scar-related VT circuits in this setting [ 108 , 109 ]. Fragmented and isolated electrograms were also more frequently observed in areas with fat.…”