What is the prevalence of a posterior variant of typical counter-clockwise atrial flutter reentry circuit as determined by entrainment mapping at the atrial roof?
In about a quarter to one-third of patients with typical counter-clockwise atrial flutter, the atrial roof is not part of the reentry circuit, suggesting a posterior variant.
AIMS: Upper turn-around of the reentry circuit in typical atrial flutter (AF) is classically described to be located in front of the superior vena cava (SVC), but circuits posterior to the SVC as well as lower loop reentry (LLR) involving only the lower part of the right atrium have been described. However, true prevalence of such AF circuits remains unknown. METHODS AND RESULTS: Fifty consecutive patients (46 men, 68 +/- 9 years old) undergoing radiofrequency (RF) ablation of typical counter-clockwise AF were prospectively investigated. Prior to RF deliverance, AF was entrained by pacing 10 ms shorter than the AF cycle length (AFCL). Post-pacing interval (PPI) at the cavotricuspid isthmus (CTI) and at the atrial roof (AR)-between SVC and the high tricuspid annulus-were determined. AR was considered to be part of the AF circuit when local PPI-AFCL was 30 ms in 12 cases (25%). In the remaining three patients, AR-PPI-AFCL did not exceed CTI-PPI-AFCL by more than 10 ms. In 42 patients, CTI-PPI-AFCL was 20 ms in 16 cases (39%). In the remaining eight patients, AR-PPI-AFCL was more than 10 ms longer than CTI-PPI-AFCL in only one instance. Taken together, AR PPI was >20 or >30 ms longer than AFCL or >10 ms longer than CTI PPI when prolonged in 17 (34%) and 12 patients (24%), respectively. CONCLUSION: In around a quarter to one-third of patients referred for RF ablation of typical AF, the atrial roof is not part of the circuit, thus they may present a 'posterior' variant of the typical counter-clockwise AF reentry circuit.
Maury et al. (Sun,) studied this question.