Autoimmune-mediated congenital heart block: Long-term cardiovascular outcome in a tertiary center experience

ABSTRACT

Introduction. CHB is a rare disease due to the immune-mediated injury of the conduction system, as result of the transplacental passage of maternal anti-SSA/Ro and anti-SSB/La autoantibodies to the fetus. High rates of mortality and pacemaker (PM) implantation have been observed. Specific long-term management recommendations are not yet available. Methods. Consecutive patients with autoimmune-mediated CHB referred to our Center from 2008 to 2019 were prospectively enrolled. In utero diagnosis was assessed by fetal echocardiography and confirmed at birth by electrocardiography (ECG). Serial clinical evaluation, ECG-monitoring and echocardiography were performed during follow-up. In patients with PM, a periodical device-monitoring was obtained. The aim of the study was to evaluate the long-term cardiovascular outcome and the clinical management of CHB. Data on self-perception of exercise tolerance were considered. CHB degree and mean ventricular heart rate (HR) in utero, at birth and during the latest follow-up were assessed. Pacing characteristics and device-related adverse events were also evaluated, involving LV dyssynchrony obtained by echocardiography. Results. 22 cases of CHB from 21 anti-SSA/Ro antibody-positive mothers were enrolled (67% III-degree CHB at fetal diagnosis;33% II-degree CHB). One intra-uterine death occurred. 16 cases were treated with a combination therapy protocol of steroids, plasmapheresis and intravenous immunoglobulin infusion. Among the 20 live births, 5 cases of incomplete CHB were observed (3 cases of I-degree and 2 cases of II-degree CHB). Patients with III-degree CHB at birth most often presented LV dilation (p=0,03;incomplete CHB 1 vs III-degree CHB 15 patients). HR at birth was for I-degree 135 bpm [127,5-147,5], for II-degree 75 bpm [72,5-77,5] and for III-degree CHB 58 bpm [50-65]. Long-term follow-up was obtained in 21 patients (one late-diagnosis presented to our Institution at the age of 8 years) at 6,9 years [4,3-8,5]. HR remained stable over time (I-degree p=0,1;II-degree p=0,18;III-degree CHB p=0,14). No cases of impaired exercise tolerance were observed. LV dilation was detected in 4 patients. 1 patient with severe LV dilation and preserved ejection fraction presented non-sustained ventricular tachycardia. A borderline QT interval was observed in a child with LV dilation. No cases of R-R interval >3 sec were revealed. QRS interval was normal in all patients with spontaneous rhythm. 6 patients underwent PM implantation (5 within the first year and 1 within the fifth year) 2 epicardial dual chamber DDD, 1 endocardial dual chamber DDD, 1 epicardial biventricular CRT-P PM and 2 epicardial single-chamber VVI-R PM were implanted. Last device follow-up showed a range of ventricular pacing of 98-100%. PM dependency was confirmed in all cases. An early abdominal PM pocket infection was successfully treated with antibiotics. Endocarditis, pneumothorax and macroscopic lead fracture or dislodgment have all been excluded. All patients presented a recovery of LV dilation and no cases of LV dyssynchrony were observed. Conclusions. In our experience, autoimmune-mediated CHB presented with a favorable long-term cardiovascular outcome. An adequate exercise tolerance was observed also in patients with spontaneous rhythm. Considering the stability of HR over time, an accurate selection of patients that need for PM should be performed. Long-term management of CHB should evaluate LV dyssynchrony in patients with PM and the presence of ventricular arrhythmias and LV dilation/dysfunction in patients with spontaneous rhythm. COVID-19.