Right atrial collision time (RACT): A novel marker of propensity for typical atrial flutter

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 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: Ninety-eight patients were included in the analysis, 41 with atrial flutter and 57 controls. Patients with atrial flutter were older, 64.7 ± 9.7 versus 52.4 ± 16.8 years (<.001), and more often male (34/41 vs. 31/57 [.003]). The AFL group mean RACT (132.6 ± 17.3 ms) was significantly longer than that of controls (99.1 ± 11.6 ms) (p < .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. A ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0, p < .01). Conclusion:RACT is a novel and promising marker of propensity for typical AFL. This data will inform larger prospective studies.

Conduction time around the mitral valve annulus has the potential to rule out postablation perimitral atrial tachycardia

“…This is understandable if one considers that MA size approximates PMAT circuit length, but offers no information about conduction time, including slow conduction, while E‐PMCT reflects both circuit length and conduction time. A recent study reported that conduction time around the tricuspid valve differed between patients with and without common AFL and could be used to determine whether to perform empirical ablation 27 . That study has many parallels to ours in that we use conduction time around the mitral annulus to predict PMAT.…”

“…A recent study reported that conduction time around the tricuspid valve differed between patients with and without common AFL and could be used to determine whether to perform empirical ablation. 27 That study has many parallels to ours in that we use conduction time around the mitral annulus to predict PMAT. However, it is significantly more difficult to create bidirectional block for the MI than for CTI, which makes weighing the decision whether or not to ablate more consequential.…”

Improved intra‐atrial conduction delay after successful ablation for atrial fibrillation by scar homogenization in right atrium

“…Atrial conduction delay has been associated with atrial flutter and a marker of atrial electrophysiologic substrate and remodeling (Redfearn et al, 2006). Recent study demonstrated that patients with atrial flutter had significantly longer RA conduction time measured by right atrial collision time (RACT) during pacing from the coronary sinus than controls and patients who developed clinical AF later showed significantly longer RACT than those who did not among atrial flutter group (Ryckman et al, 2023). (Saini et al, 2017) and ultimately improve the intra-atrial conduction delay in our patient (Figure 3).…”

The endless fascination of right atrial flutter: Can we predict its occurrence?

“…In this issue of the Journal, Rickman et al 1 take us into a new journey across the landscape of the cavo-tricuspid dependent atrial flutter (AFL) by enriching the old concepts with a novel parameter, i.e. right atrial collision time (RACT), whose role is to predict the occurrence of right common atrial flutter.…”

“…Rickman et al 1 have used this modality of pacing for investigating whether the collision time of the two wavefronts on the lateral wall of the right atrium could predict the occurrence of typical atrial flutter. For this purpose, the authors have designed a prospective study including a sample size of 98 patients, 41 having AFL and 57 as controls.…”