Characteristics of Decremental Accessory Pathways in Children.

Background: Although retrograde decremental accessory pathways (DAPs) are thought to typically present as permanent junctional reciprocating tachycardia (permanent junctional reciprocating tachycardia), they may also be diagnosed unexpectedly during electrophysiology study. We aimed to compare the clinical and electrophysiological characteristics of patients with DAPs to an age-matched cohort with nondecremental accessory pathways.

Methods And Results: We retrospectively studied pediatric patients (<21 years of age) with retrograde DAPs and an age-matched control population with nondecremental accessory pathways who underwent electrophysiology study between 2005 and 2014. Decrement was defined as rate-dependent prolongation of the local ventriculo-atrial time by >30 ms. Twenty-six patients with DAPs were compared with 73 controls (mean age at electrophysiology study 9.8±5.7 and 10.3±5.2 years, respectively [P=nonsignificant]). Compared with controls, patients with DAPs had more frequent syncope (5/26 [19%] versus 3/73 [4%]; P=0.02) and ventricular dysfunction (6/26 [23%] versus 4/73 [6%]; P=0.04). Only 11 (42%) DAP patients manifested clinical permanent junctional reciprocating tachycardia, and these patients had more syncope (5/11 [45%] versus 0/15 [0%]; P<0.01), slower orthodromic reciprocating tachycardia (176±44 beats per minute versus 229±31 beats per minute; P=0.001), and longer ventriculo-atrial times (mean maximum ventriculo-atrial times of 283±116 ms versus 208±42 ms; P=0.02) compared with those with DAPs without clinical permanent junctional reciprocating tachycardia. DAPs and controls had similar rates of acute ablation success (23/26 [89%] versus 67/73 [92%]; P=nonsignificant) and recurrences (1/23 [4%] versus 2/67 [3%]; P=nonsignificant).

Conclusions: The majority of pediatric patients with DAPs do not present with clinical permanent junctional reciprocating tachycardia. DAPs are associated with more severe symptoms, but ablation outcomes are similar to those of age-matched controls.