Decremental accessory pathway conduction after ablation and antidromic atrioventricular reciprocating tachycardia 8 years after successful radiofrequency ablation.

INTRODUCTION: This is a rare case of antidromic reciprocating tachycardia developing 8 years after successful catheter ablation.

RESULT: A 15-year-old girl had recurrence of palpitations 8 years after the ablation of manifest right posteroseptal accessory pathway. Atrial burst pacing revealed Wenckebach atrioventricular conduction with preexcitation. Wide QRS tachycardia with identical morphology to sinus rhythm associated with retrograde His potential recorded immediately after the V-wave was induced by isoproterenol infusion. Atrial premature stimulus applied at the identical timing of His potential advanced the subsequent ventricular beat and His potential.

CONCLUSION: Catheter ablation may produce decremental accessory pathway conduction and rarely cause antidromic atrioventricular reciprocating tachycardia. This may be explained by a presence of "de novo" accessory pathway with decremental conduction properties that became manifest after the first ablation.