Congenital Atrio-Ventricular Block: looking for optimal implantation timing. A single tertiary referral centre experience

Abstract Background Congenital atrio-ventricular block (CAVB) affects 1 in 15,000 live births with a mortality rate of 16–30%. It can be associated with congenital heart disease (CHD) or maternal autoantibodies and, less commonly, with viral infections or drug side effects. CAVB detected in utero is more severe, leading to higher neonatal mortality and early pacemaker (PM) implantation. Physicians face challenges in determining if and when to implant a permanent PM. This study reports on the experience of a single tertiary referral center with fetuses and children diagnosed with CAVB, focusing on incidence, PM implantation indications and timing, device types, complications, re-interventions, and long-term clinical outcomes. Methods The diagnostic database of the Paediatric Cardiology and Adult Congenital Heart Disease and Congenital and Familiar Arrhythmias Unit was reviewed to identify patients with CAVB from January 1996 to January 2023. Patients were followed for an average of 10.3 ± 7.3 years. Results Forty patients (average age 14.3 ± 11.7 years; 57.5% male; 80% with complete CAVB) were included. The median age at diagnoses was 3 (IR 0.06–6.3) years, ranging from in utero to 22 years. Nine patients (22.5%) had symptoms at time of diagnosis, 8 (20%) received a foetal diagnosis of CAVB, and 23 (57.5%) were diagnosed after casual detection of bradycardia during routine exams. Twelve patients (30%) had concomitant congenital heart disease (CHD), one patient had multiple cardiac rhabdomyomas and one had atrio-ventricular septal aneurysm at aorto-mitral junction. After a mean follow-up of 10.3 ± 7.3 years, 24 (60%) patients underwent a PM implant (15 epicardial PM and 9 transvenous PM) with a median time from the diagnosis to the implant procedure of 5 months (IR 1–18). PMs were implanted for symptoms in 45.8% and prophylactically in 54.2%. Cardiologic therapies were significantly associated with PM implantation (HR 9; P = 0.04). In the subgroup of implanted patients, ejection fraction (EF) showed an improvement at the last follow-up compared to the last pre-implantation value (P = 0.02), as was Fractional Shortening (FS) (P = 0.01) and left ventricle z-score end-systolic diameter (P = 0.045). Seven patients in PM group (29.1%) underwent a re-intervention, 6 due to lead failure and 1 due to infective endocarditis. Only 1 death (2.5%) occurred in a preterm infant with a very low body-weight at birth. Conclusion Accurate follow-up and optimal timing of PM implantation, including prophylactic pacing as per current recommendations, are associated with good long-term outcomes.