Incidence and Prognosis of Surgical Heart Block in Patients with L-transposition of the Great Arteries.

L-transposition of the great arteries (L-TGA) represents a spectrum of congenital heart defects (CHD) associated with atrioventricular block (AVB). However, the incidence and prognosis of postoperative AVB among patients with variants of L-TGA is uncertain. Assess the incidence and risk factors for postoperative AVB requiring permanent pacemaker (PPM) implantation for pediatric patients with L-TGA undergoing cardiac surgery. Single-center retrospective analysis of patients with L-TGA who underwent cardiac surgery from 2000 to 2022. Patients with postoperative AVB and those requiring PPM implantation were compared to those who did not receive a PPM. 161 cardiac surgeries were performed in 75 patients with L-TGA. Postoperative AVB occurred in 8 cases (5%) with 5 cases (3%) requiring PPM. Univariate analysis identified risk factors for PPM which included ventricular septal defect (VSD) intervention [odds ratio (OR) 58.4, p < 0.01], pre-operative non-single-ventricle physiology (OR 13.3, p = 0.02), and longer pre-operative PR interval Z-score (OR 3.3, p < 0.01). Excluding biventricular conversions, no surgery (n = 116) in patients with univentricular circulation required a PPM in the postoperative period due to AVB. Multivariate analysis did not identify any statistically significant risk factors for AVB requiring PPM. The overall risk of postoperative AVB in L-TGA was 5% despite the anatomic vulnerability of the conduction system. However, L-TGA patients appear less likely to recover AV conduction than all comers to CHD surgery (38% L-TGA vs 60% overall, p < 0.01) and may be considered for earlier PPM placement.