An Integrated Approach to Radiofrequency Ablation of Para-Hisian Accessory Pathways in Pediatric Patients

BACKGROUND R03; Pediatric para-Hisian accessory pathway (PHAP) ablation carries greater challenges than in adults due to smaller Koch's triangles. OBJECTIVE We aimed to develop an ablation strategy to enhance both efficacy and safety in this population. METHODS This single-center retrospective study included 41 pediatric patients (median age 10 years) between January 2023 and September 2025. The strategy comprised: (1) pace-mapping validation of ventricular insertion sites in manifest pathways, using adenosine-induced maximal pre-excitation as a template; and (2) subvalvular retroflexion for catheter stabilization in patients ≥10 kg. Energy delivery was titrated with guidance from para-Hisian pacing to distinguish near-field His signals, and atrial overdrive pacing was used to monitor AV conduction during any junctional acceleration. RESULTS All 41 cases achieved acute success with no permanent complications. Mechanical pathway block occurred in 43.9% (18/41) during mapping. Subvalvular retroflexion enabled stable ablation in 90.2% (37/41) of cases, three patients <10 kg required supravalvular approaches, and one concealed pathway was successfully ablated from the non-coronary cusp. Over a median 19-month follow-up, recurrence occurred in 7.4% (3/41). Univariate analysis showed higher recurrence risk for pathways with a W-pattern in lead V1 and for those in the superior mid-septal region. Among manifest pathways, adding pace-mapping to activation mapping showed a lower recurrence rate (0% vs 21.4%), a hypothesis-generating trend that did not reach statistical significance (p = 0.056). CONCLUSION Our integrated ablation strategy effectively addresses the unique challenges of pediatric PHAP ablation, achieving durable efficacy and high procedural safety.