Abstract 2615: Multiple Accessory Pathways in Pediatric Patients with Structural Heart Disease

Abstract

Pts with structural heart disease (SHD) such as Ebstein’s and certain cardiomyopathies often have multiple accessory pathways (AP’s) at mapping procedures. The goals of this study were to determine the incidence of multiple AP’s (multAP) in a large pediatric cohort undergoing electrophysiology study, contrasting pts with and without SHD, and to measure the influence of multAP on ablation outcomes. Methods: Data from all patients (n=1089) undergoing catheter mapping and/or ablation for AP’s at Children’s Hospital Boston from 1990 through 2006 were reviewed. The AP locations were divided into segments along the septum(S), tricuspid(TV) and mitral (MV) valves. The presence of multAP was defined as two or more APs with distinct conduction characteristics mapped at least 1 cm apart. Acute ablation success was defined as elimination of all AP conduction. Recurrence was defined as return of conduction in any one or more AP’s. A total of 1229 APs (36% concealed AP) were mapped in 1089 patients (aged 12.9 ± 4yrs) with locations along TV in 18%, S in 39%, and MV in 43%. Ablation attempts (n=1306) were successful in 94% overall (92% TV, 92% S, and 97% MV), with 8% recurrence rate. A subgroup of 111 pts (10%) had multAP, involving 250 distinct APs. MultAP were significantly more common (p<0.001) among SHD pts (25%) than those without SHD (8%). Ebstein’s, AV discordance, and cardiomyopathy accounted for 28/30 (93%) of SHD pts with multAP. Ebstein’s(OR 8.7,p<0.001) and myopathic pts(OR13.3, p<0.001) were more likely to have multAP. AP locations in SHD pts shifted toward TV, driven by Ebstein’s pts. Acute ablation success did not differ between multAP and a solitary AP (91% vs. 94%, p= n.s.), though recurrence rate was higher for multAP (19% vs. 8%, p<0.001). Acute success was lower in SHD compared to those without SHD (85% vs. 95%, p<0.01), and recurrence was higher (17% vs. 8%, p<0.05). MultAP can be found in 10% of pediatric patients, and are far more common in SHD compared to those with normal hearts. Both the presence of multAP and SHD can negatively influence ablation outcomes.