Abstract 2853: Usefulness of Entrainment Response Analysis in Distinguishing the Macroreentrant Channel-dependent Atrial Tachycardia From the Macroreentrant Channel-independent Atrial Tachycardia
Background: It has been shown that two types of macroreentrant atrial tachycardia (AT) exist, i.e. channel dependent (CD-) and independent (CI-) AT. Focal energy application to the channel is often effective in terminating the CD-AT, whereas linear lesion between obstacles is required to terminate the CI-AT. However, no specific criteria in distinguishing the CD-AT from CI-AT has been established.
Objective: We hypothesized that entrainment response in CD-AT is different from that in CI-AT, because of different circuit components. Thus, we examined the change in the post pacing interval (PPI) after entrainment between CD- and CI-AT. Moreover, we elucidated whether the entrainment response is useful in differentiating the CD-AT from the CI-AT.
Methods: Seven patients with CD-AT and 7 patients with CI-AT were included in this study. The 3D mapping using the CARTO or EnSite 3000 system was performed during tachycardia in all patients. Then entrainment pacing was delivered from cavotricuspid isthmus or coronary sinus. PPI after entrainment at a rate 5, 10, 15 and 20 beats/minute faster than tachycardia rate were analyzed. The increment of the PPI following increase in the pacing rate from 5 to 10 beats/minute (PPI-10), from 5 to 15 beats/minute (PPI-15) and from 5 to 20 beats/minute (PPI-20) were compared between the CD-AT and CI-AT patients.
Results: There was no significant difference among PPI-10, PPI-15 and PPI-20 in the CI-AT. However, PPI-15 was longer than PPI-10 (p<0.002) and PPI-20 was further longer than PPI-15 (p<0.03) in CD-AT. The PPI-10, PPI-15 and PPI-20 in the CD-AT patients were significantly longer than those in the CI-AT patients, respectively (15±6 vs. 1±2 msec; p<0.002, 39±23 vs. 2±3 msec; p<0.002 and 47±20 vs. 2±3 msec; p<0.005, respectively). The non-contact mapping showed that the increment in the post pacing interval in CD-AT was caused by the increase in the conduction interval over the channel. In CD-AT, focal radiofrequency energy application to the channel terminated the tachycardia, whereas, linear ablation was required to terminate the CI-AT.
Conclusions: Analysis of the PPI after entrainment is useful in differentiating the CD-AT from CI-AT and facilitates the identification of an appropriate ablation site.