Pediatric/Adult Congenital Heart Disease -> Adult Congenital Heart Disease D-AB15 - Pacing in Patients with Congenital Heart Disease (ID 44) Abstract


Background: Congenitally corrected transposition of the great arteries (CCTGA) is associated with spontaneous AV block and pacing-induced cardiomyopathy. His bundle pacing (HBP) is a potential alternative to conventional CRT.
Objective: To determine the outcomes of HBP for CCTGA.
Methods: Retrospective data were collected from 9 international ACHD centers. An HV <35 ms was considered proximal LBB pacing.
Results: HBP or LBB pacing was attempted for 14 CCTGA patients (median 20 yrs, 86% male). Prior surgery was performed in 5 (TV replacement in 3 and VSD closure in 2). A prior cardiac device was present in 6. Conduction system pacing (HBP=10, LBBP=2) was acutely successful in 12 (86%) without complication. 3D mapping was used in 9 cases to identify the anatomic course of His bundle and proximal LBB within the morphologic LV. A conventional left conduction system was observed to originate below the pulmonary valve with extensive ramifications (FIGURE). The median implant HV interval was 42 ms (IQR 35 - 48), R wave 7 mV (IQR 5 - 18) and threshold 0.5V (IQR 0.4 - 1.3) at 0.75 ms (IQR 0.4 - 1; 10 non-selective, 2 selective). QRSd decreased with preexisting pacing (164 vs 112 ms, p=0.03) but not overall (117 vs 112 m; p=0.46) (FIGURE). At a median of 17 mos (IQR 7 - 32), all patients were alive without significant change in pacing threshold (0.5V vs 0.875V, p=0.2) or lead failure. RV systolic function was unchanged (p=0.5).
Conclusion: Permanent conduction system pacing is feasible in CCTGA due to an extensive morphologic left conduction system. Narrow paced QRS and stable lead thresholds were observed at intermediate follow-up. Further study is needed to determine long-term outcomes in this challenging population.