Ap-452681-4 unusual initiation of orthodromic atrioventricular reentrant tachycardia with a junctional beat

Spontaneous initiation of orthodromic atrioventricular reentrant tachycardia (AVRT) is commonly noted with premature ventricular beat (PVC). In the lab it can be initiated with programmed atrial or ventricular stimulation. We report the initiation of AVRT (with left lateral accessory pathway) with a junctional beat. Case report A 69-year-old male with history of Parkinson’s, HTN, who has had palpitations for few years. Event monitor showed narrow and wide complex tachycardia and he was scheduled for electrophysiology (EP) study and catheter ablation. He presented in sinus rhythm. EP study revealed normal AH and HV intervals with no evidence of preexcitation. Narrow complex supraventricular tachycardia (SVT) initiated spontaneously as noted in the Figure. SVT (short RP) was also initiated with ventricular and atrial extra stimuli without critical AH dependence. There was eccentric atrial activation during SVT with the earliest atrial activation on distal CS. Ventricular overdrive pacing (VOD) during SVT lead to VAV response ruling out atrial tachycardia. There was LBBB during SVT that increased the VA time from 94 ms to 170 ms. The tachycardia terminated with single fused PVC with VA block. Based on these findings a diagnosis of AVRT was made and the concealed left lateral accessory pathway was ablated at 1’o clock on mitral annulus via transseptal catheterization. This case illustrates spontaneous initiation of AVRT using a left lateral accessory pathway with a junctional beat that conducted retrogradely through the accessory pathway. This is a novel finding that has not been demonstrated prior to this. Hence a junctional beat can spontaneously initiate AVRT similar to a PVC. Similarly JPC can initiate AVNRT especially during ablation at the slow pathway region and should not be presumed to be junctional tachycardia.