Abstract MP164: Electrophysiologic Conservation of Epicardial Conduction Dynamics After Myocardial Infarction in Newborn Piglets

Abstract

Introduction: Newborn piglets reportedly exhibit natural heart regeneration after myocardial infarction (MI). However, the electrophysiologic properties of this regenerated muscle have not been examined. We hypothesized that epicardial electrical conduction is preserved after MI in newborn piglets. Methods: Yorkshire-Landrace piglets underwent left anterior descending coronary artery ligation on postnatal day 1 (P1, n=4) or postnatal day 7 (P7, n=7), infarcting the anteroseptal left ventricle through which the Purkinje conduction system passes. After 7 weeks, cardiac magnetic resonance imaging (MRI) was performed with late gadolinium enhancement for fibrosis analysis. Epicardial conduction mapping was performed using custom 3D-printed, 256-channel high-resolution mapping arrays (Fig 1A). Age- and weight-matched healthy pigs served as controls (n=7). Data are expressed as mean±SD. Results: MRI analysis revealed significant differences between the control, P1, and P7 groups in ejection fraction (47.6±3.1% vs 37.6±3.3% vs 30.2±6.6%, p<0.001, Fig 1B) and the degree of transmural anteroseptal LV scar (0.0±0.0% vs 9.1±5.4% vs 15.4±4.2%, p<0.001), respectively. Evidence of infarcted myocardium was identified with high-resolution mapping in the P1 and P7 piglets (black arrows, Fig 1C-F). Epicardial electrical conduction was preserved in control and all P1 pigs (Figs 1C-D), whereas variable conduction block or aberrant propagation were observed in all P7 pigs (Fig 1E-F, p=0.001). Conclusion: P1 piglets exhibited incomplete natural cardiac regeneration after MI but nevertheless demonstrated electrophysiologic conservation of epicardial conduction dynamics.