Pediatric/Adult Congenital Heart Disease -> Translational D-PO01 - Featured Poster Session (ID 11) Poster

D-PO01-121 - Distribution Of Conduction Disorders In Patients With Congenital Heart Disease And Right Atrial Volume Overload (ID 909)


Background: Patients with right atrial (RA) volume overload are prone to developing atrial fibrillation (AF), which may be related to conduction disorders occurring due to atrial stretch. In order to improve treatment strategies aimed at eliminating AF, it is essential to understand the substrate underlying AF in these patients, which may be different or more severe than in the general population.
Objective: To quantify characteristics of atrial conduction disorders during sinus rhythm in patients with RA volume overload. Knowledge of the characteristics of conduction disorders during sinus rhythm is an essential first step towards unraveling the substrate of AF in this specific patient population.
Methods: 31 patients (18 female, age: 49±14 yrs) undergoing surgery for an interatrial shunt underwent epicardial mapping of the right atrium (RA), Bachmann’s bundle (BB) and left atrium (LA) during sinus rhythm. Conduction delay (CD) was defined as inter-electrode conduction time of 7-11ms and conduction block (CB) as conduction time ≥12ms. Prevalence of CD/CB (percentage of mapped region), length of CD/CB lines, and severity of CB (75th percentile of CTs ≥12ms) were analyzed.
Results: All patients had some degree of CD and CB. Prevalence of CD and CB was higher in the RA and BB than in the LA (p<0.0083 after Bonferroni correction). The longest CB line within each patient was found in the RA in most patients (52%). Inter-individual variation in prevalence and lengths of lines was considerable. CB was more severe in the RA than in the LA (p<0.0083). Within the RA, conduction disorders were more prevalent and more severe in the intercaval region than in the RA free wall (p<0.05). When comparing patients with and without a history of AF, prevalence and characteristics of conduction disorders only differed in BB, yet only 5 patients (16%) had a history of AF. Patients with AF had a higher prevalence of CB (p=0.047) and longer CB lines (p=0.041) in BB.
Conclusion: In patients with RA volume overload, conduction disorders during sinus rhythm are most pronounced in the RA - particularly the intercaval region - and BB, rather than the LA. The next step is to study the characteristics of conduction disorders in relation to initiation and perpetuation of AF in these patients.