Spatial and Temporal Variability of Rotational, Focal and Irregular Activity: Practical Implications for Mapping of Atrial Fibrillation

Abstract

Background Charge density mapping of atrial fibrillation (AF) reveals dynamic patterns of localised rotational activation (LRA), irregular activation (LIA) and focal firing (FF). Their spatial stability, conduction characteristics and the optimal duration of mapping required to reveal these phenomena and has not been explored. Methods Bi-atrial mapping of AF propagation was undertaken and variability of activation patterns quantified up to a duration of 30-seconds(s). The frequency of each pattern was quantified at each vertex of the chamber over 2 separate 30s recordings prior to ablation and R2 calculated to quantify spatial stability. Regions with the highest frequency were identified at increasing time durations and compared to the result over 30s using Cohen’s kappa. Properties of regions with the most stable patterns were assessed during sinus rhythm and extrastimulus pacing. Results In twenty-one patients, 62 paired LA and RA maps were obtained. LIA was highly spatially stable with R2 between maps of 0.83(0.71-0.88) compared to 0.39(0.24-0.57) and 0.64(0.54-0.73) for LRA and FF, respectively. LIA was also most temporally stable with a kappa of >0.8 reached by 12s. LRA showed greatest variability with kappa>0.8 only after 22s. Regions of LIA were of normal voltage amplitude (1.09mv) but showed increased conduction heterogeneity during extrastimulus pacing (p=0.0480). Conclusion Irregular activation patterns characterised by changing wavefront direction are temporally and spatially stable in contrast with rotational patterns that are transient with least spatial stability. Focal activation appears of intermediate stability. Regions of LIA show increased heterogeneity following extrastimulus pacing and may represent fixed anatomical substrate.

Characterization of persistent atrial fibrillation with non‐contact charge density mapping and relationship to voltage

“…Yet the consistent observation of temporally stable activity in patient‐specific locations, LIA in particular, strongly suggests this reflects an underlying fixed atrial substrate. Our observations regarding the frequent occurrence of LIA confirm those of others using this approach 18,30,31 . Using optical mapping ex vivo, fibrotic regions have been shown to harbor microscopic intramural re‐entrant circuits that can act as AF drivers 32 .…”

“…However, this earlier generation system was of lower spatial resolution and does not utilize accurate patient‐specific ultrasound chamber geometry. Using the current system, LIA locations detected during AF co‐localize to areas of slow conduction during non‐AF paced rhythm, providing further evidence that these represent localized areas of abnormal substrate 31 …”

Atrial conduction velocity mapping: clinical tools, algorithms and approaches for understanding the arrhythmogenic substrate

“…Kodex-EPD Philips cardiac imaging and mapping system uses dielectric mapping to estimate wall thickness [22], which can be compared to CV using openEP software [23]; future iterations of the software may combine these analyses. Acutus Medical AcQMap offers high-resolution global maps, and includes a SlowZone Locator where multiple maps are combined to identify regions of consistently slow conduction [24,25]. Exciting new developments across the electroanatomic mapping systems offer detailed analysis of the atrial substrate.…”

Is there rule to the chaos: Defining stable patterns in atrial fibrillation

“…In this issue of the Journal of Cardiovascular Electrophysiology , Pope et al studied the spatial stability of AF drivers and optimal duration of mapping while simultaneously mapping AF activation in both the left and right atria using the AcQMap system in 21 patients undergoing first time catheter ablation 8 . The wavefront patterns studied were localized rotational activation (LRA)—defined as a smooth depolarization wavefront rotating 360° around a central point within 300 mm 2 , LIA—defined as a difference in angle of more than 90° between the entry and exit of a conduction from a confined region (200 mm 2 , and not meeting criteria for LRA), and focal firing (FF)—defined as a primary activation that extends centrifugally from its origin.…”