AUTHOR=Wang Hanjay , Pong Terrence , Obafemi Oluwatomisin O. , Lucian Haley J. , Aparicio-Valenzuela Joy , Tran Nicholas A. , Mullis Danielle M. , Elde Stefan , Tada Yuko , Baker Sam W. , Wang Caroline Y. , Cyr Kevin J. , Paulsen Michael J. , Zhu Yuanjia , Lee Anson M. , Woo Y. Joseph 

TITLE=Electrophysiologic Conservation of Epicardial Conduction Dynamics After Myocardial Infarction and Natural Heart Regeneration in Newborn Piglets

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2022.829546

DOI=10.3389/fcvm.2022.829546

ISSN=2297-055X

ABSTRACT=<p>Newborn mammals, including piglets, exhibit natural heart regeneration after myocardial infarction (MI) on postnatal day 1 (P1), but this ability is lost by postnatal day 7 (P7). The electrophysiologic properties of this naturally regenerated myocardium have not been examined. We hypothesized that epicardial conduction is preserved after P1 MI in piglets. Yorkshire-Landrace piglets underwent left anterior descending coronary artery ligation at age P1 (<italic>n</italic> = 6) or P7 (<italic>n</italic> = 7), After 7 weeks, cardiac magnetic resonance imaging was performed with late gadolinium enhancement for analysis of fibrosis. Epicardial conduction mapping was performed using custom 3D-printed high-resolution mapping arrays. Age- and weight-matched healthy pigs served as controls (<italic>n</italic> = 6). At the study endpoint, left ventricular (LV) ejection fraction was similar for controls and P1 pigs (46.4 ± 3.0% vs. 40.3 ± 4.9%, <italic>p</italic> = 0.132), but significantly depressed for P7 pigs (30.2 ± 6.6%, <italic>p</italic> &lt; 0.001 vs. control). The percentage of LV myocardial volume consisting of fibrotic scar was 1.0 ± 0.4% in controls, 9.9 ± 4.4% in P1 pigs (<italic>p</italic> = 0.002 vs. control), and 17.3 ± 4.6% in P7 pigs (<italic>p</italic> &lt; 0.001 vs. control, <italic>p</italic> = 0.007 vs. P1). Isochrone activation maps and apex activation time were similar between controls and P1 pigs (9.4 ± 1.6 vs. 7.8 ± 0.9 ms, <italic>p</italic> = 0.649), but significantly prolonged in P7 pigs (21.3 ± 5.1 ms, <italic>p</italic> &lt; 0.001 vs. control, <italic>p</italic> &lt; 0.001 vs. P1). Conduction velocity was similar between controls and P1 pigs (1.0 ± 0.2 vs. 1.1 ± 0.4 mm/ms, <italic>p</italic> = 0.852), but slower in P7 pigs (0.7 ± 0.2 mm/ms, <italic>p</italic> = 0.129 vs. control, <italic>p</italic> = 0.052 vs. P1). Overall, our data suggest that epicardial conduction dynamics are conserved in the setting of natural heart regeneration in piglets after P1 MI.</p>