Abstract 17134: Misleading Long PPI-TCL from Entrainment of Cavotricuspid Isthmus-Dependent Right Atrial Flutter
Background: Entrainment from the cavotricuspid isthmus (CTI) is consistent with CTI-dependent atrial flutter (AFL) if the post-pacing interval (PPI) matches the tachycardia cycle length (TCL). Conduction slowing during overdrive pacing can cause PPI-TCL >30 ms, which falsely suggests other mechanisms.
Purpose: To determine the frequency of a long (>30 ms) PPI-TCL at the CTI during CTI-dependent atrial flutter and to determine the anatomic location of conduction slowing.
Methods: We retrospectively screened 243 consecutive patients (pts) referred for AFL ablation. All pts had a 20-pole diagnostic catheter (1–10: CS; 11–20: HRA to LRA along the tricuspid annulus) to measure conduction times in anatomic segments depicted in the figure. 60 pts with CTI-dependent AFL confirmed by termination with CTI ablation had entrainment from the CTI and were grouped by PPI-TCL (short: ≤30ms, long: >30ms).
Results: CTI entrainment produced a long PPI-TCL in 18% of pts with CTI-dependent AFL (Tbl.). Compared to short PPI-TCL pts, long PPI-TCL pts had similar AFL conduction times by anatomic segment (Fig.) but greater fluctuation in TCL (Tbl.). With entrainment, long PPI-TCL pts demonstrated conduction slowing (% in bold in Fig), predominantly in the inferior and septal segments.
Conclusions: A potentially misleading PPI-TCL >30 ms with entrainment at the CTI is common in pts with CTI-dependent AFL and should be particularly suspected in AFL with fluctuating TCL. Conduction slowing within the inferior and septal segments of the AFL circuit has to be considered as a potential cause for long PPI-TCL in these subjects.
- © 2010 by American Heart Association, Inc.