Abstract
Introduction: The risk of typical atrial flutter (AFL) is
increased proportionately to right atrial (RA) size or right atrial
scarring that results in reduced conduction velocity. These
characteristics result in propagation of a flutter wave by ensuring the
macro re-entrant wave front does not meet its refractory tail. The time
taken to traverse the circuit would take account of both of these
characteristics and may provide a novel marker of propensity to develop
AFL. Our goal was to investigate right atrial collision time (RACT) as a
marker of existing or future typical AFL.
Methods: This single centre, prospective study recruited
consecutive typical AFL ablation patients that were in sinus rhythm.
Controls were consecutive electrophysiology study patients
>18 years of age. While pacing the coronary sinus (CS)
ostium at 600 ms, a local activation time map was created to locate the
latest collision point on the anterolateral right atrial wall. This RACT
is a measure of conduction velocity and distance from CS to a collision
point on the lateral right atrial wall.
Results: 98 patients were included in the analysis, 41 with
atrial flutter and 57 controls. Patients with atrial flutter were older,
64.7 ± 9.7 vs 52.4 ± 16.8 years (<0.001) and more often male
(34/41vs 31/57 (0.003)). The AFL group mean RACT (132.6±17.3 ms) was
significantly longer than that of controls (99.1±11.6 ms)
(p<0.001). A RACT cut-off of 115.5 ms had a sensitivity and
specificity of 92.7% and 93.0% respectively for diagnosis of atrial
flutter. An ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0,
p<0.01).
Conclusion : RACT is a novel and promising marker of propensity
for typical AFL. This data will inform larger prospective studies. The
ability to predict AFL would be of significant clinical value to guide
anticoagulation and ablation decisions.
Key words: Typical atrial flutter; wavefront collision, electroanatomic
mapping, ablation, atrial fibrillation, electrophysiological studies.