Abstract 13443: Dead Antegrade Fast Pathway: A Dilemma for Atrioventricular Nodal Re-Entry Tachycardia Ablation

Abstract

Background: Catheter ablation is the first-line treatment option for symptomatic atrioventricular nodal re-entry tachycardia (AVNRT). Ablation of the slow pathway is preferred over the fast pathway in Typical AVNRT, given that it has a lower risk of heart block. Still, baseline conduction abnormalities and findings on the Electrophysiology (EP) study can alter the ablation strategy. Case: We report a case of a 61-year-old male who was referred to EP clinic for symptomatic suspected AVNRT. His baseline electrocardiogram (EKG) showed normal sinus rhythm with PR prolongation, right bundle branch block, and left anterior fascicular block. EP study was performed, which showed prolonged AH interval with normal HV interval (Figure 1). Typical AVNRT was induced with a premature atrial complex; there was no AV nodal jump before the tachycardia, but it had a long AH interval (Figure 2). There was no evidence of pre-excitation. Discussion: Since there was no antegrade conduction through the fast pathway, conventional slow pathway ablation was not viable as it would make the patient pacemaker (PM)-dependent. Even ablating the fast pathway, though not PM-dependent, would still put him at risk for complete heart block, especially when his antegrade conduction via the slow pathway was unreliable. Hence PM was discussed with the patient before ablation. The fast pathway was mapped and ablated (Figures 3, 4, and 5) without complication, and PM was implanted. Conclusion: This case emphasizes the role of fast pathway ablation in symptomatic AVNRT in patients with conduction abnormalities and the importance of EP study to see the need for PM post-ablation.