INTRODUCTION
Typical right atrial flutter (RAFl) is a common cardiac arrhythmia
mainly treated by catheter ablation as a first line therapy (1, 2). This
technic is associated with a high success rate around 95% (3). However,
the absence of recurrences following the procedure depends highly on the
validation of bidirectional cavo-tricupsid isthmus (CTI) block (4, 5).
This block is usually validated by differential pacing across the CTI
line and needs two or three catheters to be demonstrated (6, 7). Indeed,
CTI block is routinely validated by coronary sinus (CS) pacing proving a
descending activation of the right atrium (RA) lateral wall. Then, when
pacing is performed close to the lateral aspect of the line of block,
activation of the infero-septal part of the RA occurs before the septal
part of CTI line (8). Finally, CTI line block is confirmed with double
potential recorded all along the line during CS pacing (9). The use of
multiple catheters, through several venous access, increases procedural
cost, and potentially complications. Further, this strategy can be
jeopardized by limited venous access (tortuosity or abnormality).
Recently, measurement of PR interval on surface ECG has been proposed as
a new and easy endpoint to validate CTI line block (10). Indeed, PR
interval measured during atrial pacing from the tip of ablation catheter
at different sites of the tricuspid annulus could predict CTI block. We
propose to study the predictive value of differential surface ECG PR
measurement to assess CTI block to validate a single catheter approach
to perform RAFl ablation.