Huntley GD, et al. - Given that placement of an epicardial pacemaker system was often preferred over an endocardial system in patients who have undergone a Fontan operation, the researchers determined how these two systems perform over time in patients with Fontan palliation. From 1994 to 2014, a retrospective review of adults with Fontan palliation who had pacemaker implantation and interrogation data at Mayo Clinic was performed. Findings revealed that ventricular epicardial leads were correlated with temporal decrease in impedance and increase in energy threshold (ET) compared to endocardial leads. Epicardial leads had higher rates of failure but similar generator longevity in comparison to endocardial leads regarding clinical outcomes. It was noted that ventricular epicardial leads were connected with temporal decrease in impedance and increase in ET. They found that epicardial leads had a higher rate of failure but similar generator longevity compared to endocardial leads.