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.