724-2 Electrophysiologic Endpoints of Successful Radlofrequency Catheter Modification for Atrioventricular Nodal Reentrant Tachycardia. Are There “Good” and “Bad” Persistent Echoes?

Transcatheter treatment of atrioventricular nodal reentrant tachycardia (AVNRT) modifies but frequently does not eliminate the electrophysiologic substrate for reentry. The extent of modification required thus remains unclear. High recurrence rates have been reported when single AV nodal echos (AVNe) remain inducible. We, therefore, prospectively evaluated the characteristics of AVNe pre and post AV nodal modification. Results Ablation was deemed successful when sustained AVNRT could not be induced on isoproternol (ISO). After successful ablation, AVNe was inducible in 24 pts and noninducible in 72 pts. Other electrophysiologic parameters in these two groups were comparable with similar increases in 1:1 AV block cycle lengths (356 to 413 and 368 to 400 msec, p l 0.005) and AVNERP (258 to 317 and 264 to 313 msec, p l 0.001) pre to post ablation. In Group 1 patients, persistent AVNes following successful ablation (good echoes) were associated with an increase in AH interval in all but one patient as compared to AVNes seen either preablation or during ablation attempts when tachycardia was still inducible (bad echoes) (366.9 ± 113 vs 279.6 ± 80 msec, p l 0.001). In Group 2 patients, when the AH interval of AVNes was unchanged from baseline, further ablation attempts were required to achieve noninducibility and also resulted in abolition of dual physiology. During a mean follow-up of 11 ± 4 months, only one of the 96 patients had a recurrence. Conclusion Successful modification of the slow pathway for AVNRT is associated with persistent AVNes with longer AH intervals possibly due to slow pathway injury or multiple slow pathways. Post ablation, AVNes with unchanged AH interval from baseline require further ablation for successful outcome.