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Epicardial interventions have forged new frontiers in cardiac ablation and device therapies. Healthy human hearts typically present with significant adipose tissue layers superficial to the ventricular myocardium and may hinder success or increase the complexities of epicardial interventions. We quantitatively evaluated the distribution of epicardial adipose tissue on the surface of human hearts and provided high-fidelity 3-dimensional reconstructions of these epicardial adipose tissue layers. The regional thickness of adipose tissues was analyzed at 51 anatomical reference points surrounding both ventricles and compared to specific patient demographics. Adipose deposits on the human hearts displayed characteristic patterns, with the thickest accumulations along the interventricular septa (anterior, 9.01 ± 0.50 mm; posterior, 6.78 ± 0.50 mm) and the right ventricular margin (7.44 ± 0.57 mm). We provide one of the most complete characterizations of human epicardial adipose location and relative layer thickness. These results are considered fundamental for an underlying anatomic understanding when performing procedures within the pericardial space., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Assessment of origin of ventricular tachycardias (VTs) arising from epicardial vs endocardial sites are largely challenged by the available criteria and etiology of cardiomyopathy. Current electrocardiographic (ECG) criteria based on 12-lead ECG have varying sensitivity and specificity based on site of origin and etiology of cardiomyopathy., Objectives: This study sought to test the hypothesis that epicardial VT has a slower initial rate of depolarization than endocardial VT., Methods: We developed a method that takes advantage of the fact that electrical conduction is faster through the cardiac conduction system than the myocardium, and that the conduction system is primarily an endocardial structure. The technique calculated the rate of change in the initial VT depolarization from a signal-averaged 12-lead ECG. We hypothesized that the rate of change of depolarization in endocardial VT would be faster than epicardial. We assessed by applying this technique among 26 patients with VT in nonischemic cardiomyopathy patients., Results: When comparing patients with VTs ablated using epicardial and endocardial approaches, the rate of change of depolarization was found to be significantly slower in epicardial (6.3 ± 3.1 mV/s vs 11.4 ± 3.7 mV/s; P < 0.05). Statistical significance was found when averaging all 12 ECG leads and the limb leads, but not the precordial leads. Follow up analysis by calculation of a receiver-operating characteristic curve demonstrated that this analysis provides a strong prediction if a VT is epicardial in origin (AUC range 0.72-0.88). Slower rate of change of depolarization had high sensitivity and specificity for prediction of epicardial VT., Conclusions: This study demonstrates that depolarization rate analysis is a potential technique to predict if a VT is epicardial in nature., Competing Interests: Funding Support and Author Disclosures This work was supported in part by the University of Minnesota’s Medical School Academic Investment Education Program grant and the Institute for Engineering in Medicine. Dr Prisco is funded by the National Institutes of Health T32 HL144472. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. All rights reserved.)