Atrial extrasystoles unmask early electropathology in pediatric congenital heart disease

Abstract

Abstract Background Despite improvement in (timing of) of intervention or surgery, atrial fibrillation (AF) still occurs more often and at a younger age in patients with congenital heart disease (CHD) than in the general population. This suggests that in this population atrial conduction is already affected in an early stage. Purpose To unmask early, enhanced non-uniform anisotropic atrial conduction in pediatric patients with CHD by examining the impact of spontaneous aberrant atrial extrasystoles (AES) on atrial conduction. Methods Twenty-one pediatric patients with various CHD (mild 43%, moderate 24% and severe 33%) (median age=1.8 years [0.2–7.3]) undergoing primary cardiac surgery were included for an intra-operative epicardial mapping of both atria, including Bachmann's bundle. Conduction velocity (CV), localized areas of conduction delay and/or block (CD, CB and continuousCDCB) and unipolar electrogram (EGM) characteristics (voltages and amount of fractionated potentials) were quantified during sinus rhythm (SR) and compared with corresponding AES beats. Results During 41 AES median unipolar voltage and CV decreased compared to corresponding SR beats (7.08 [5.50–9.10] mV vs. 5.71 [3.95–7.48] mV, p<0.001); 87.9 [76.7–101.6] cm/s vs. 84.5 [73.0–93.6] cm/s, p=0.013; respectively), whereas the amount of fractionated potentials increased (12.7 [3.5–18.2] % vs. 19.5 [10.5–30.0] %, p<0.001). Conduction disorders, consisting of CD, CB and cCDCB, were more prominent during AES (4.5 [2.3–6.3] %; 1.5 [0.0–4.3] %; 6.3 [2.6–11.2] %, respectively) (all p≤0.006). Differences in EGM morphology and conduction heterogeneity were not influenced by the degree of the prematurity of AES (p>0.05). Conclusions AES in pediatric patients with CHD cause localized areas of conduction slowing and block, potentials with lower unipolar voltages and a higher degree of fractionation compared to SR potentials, independent of its prematurity. Our findings indicate that in pediatric patients with CHD, early, enhanced non-uniform anisotropic atrial conduction is already present and can be unmasked by AES. These insights are the first step in further understanding the time course of AF in CHD patients. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CVON-AFFIPNWO-Vidi