Left atrial deceleration outperforms regional conduction velocity in predicting arrhythmia recurrence following atrial fibrillation ablation

Figures

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  Figure 1. Defining regional slowest conduction velocity (CVmin) and true deceleration (TD). A: An activation map of the left atrium (LA) for 1 atrial fibrillation (AF) patient is shown during high right atrial (RA) pacing at 750 ms. The vector (white dashed line) of the propagating wavefront is first determined for each LA region by dividing the map into 5-ms isochrones. Next, the regional CV is calculated traveling parallel with the vector and perpendicular to the greatest number of isochrones over the shortest distance. Examples of the conduction velocities of the anterior wall (left, vector AB) and posterior wall (right, vector CD) are highlighted. The regional CVs are 0.78 and 1.1 m/s, respectively. B: Schematic activation maps of a single LA region of varying length (in millimeters), divided into 6 colored 10-ms isochrones parallel to the propagating wavefront. The difference between the regional CV, CVmin, and TD are illustrated. The region where TD occurs is highlighted by the black arrows. i: CV is slow and constant, so there is no TD. ii: Conduction slowing is evident at the third isochrone and occurs over 1 isochrone. CVmin is 0.4 m/s, while TD is 60 m/s2. iii: Conduction slowing…

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  Figure 2. Slowest regional conduction velocity (CVmin) and maximum true deceleration (TDmax) in control and atrial fibrillation (AF) patients. One control patient and 3 AF patients are presented column wise. (Top) Activation maps of the left atrium (LA) during high right atrial (RA) pacing at 750 ms (10-ms isochrones). The white dotted arrow indicates the propagating vector with the slowest CV across the highlighted LA region (control: anterior; AF1: roof; AF2: inferior; AF3: anterior wall). The propagating vector is depicted below each activation map with corresponding isochronal colors, and their widths are measured to compute CV per isochrone. (Bottom) Plots of CV for each isochrone. The control and AF1 patients both have no TD. The AF2 patient has 1 TD over 2 isochrones (TDmax 60 m/s2, CVmin 0.17 m/s). The AF3 patient has 2 TD, the first over one isochrone and the second over 2 isochrones (TDmax 50 m/s2, CVmin 0.39 m/s).

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  Figure 3. Relationship of bipolar voltage to clinical true deceleration (TD) in atrial fibrillation (AF) patients. A, B: Two examples of patients in the AF cohort with clinical TD (maximum TD [TDmax] >110 m/s2), demonstrating the relationship between TD and bipolar voltage. i: An isochronal left atrial (LA) activation map with the corresponding dimension of each isochrone in mm along the propagating vector (A→B) on the anterior wall. ii: A graphical representation of conduction velocity (CV) against time separated into 10-ms isochrones. Areas demonstrating TD are highlighted. Clinical TD sites are characterized by sudden acceleration over 1 isochrone followed by rapid deceleration over a second isochrone. iii: The relationship between TD sites and bipolar voltage, using <0.5 mV cutoffs. iv: The relationship between TD sites and bipolar voltage, using a higher <1-mV cutoff. In both patient examples, isochrones exhibiting acceleration and clinical TD occur in a low voltage area defined by <1 mV but not by <0.5 mV. BI = bipolar voltage; CVmin = slowest regional conduction velocity; LAT = local activation time.

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  Figure 4. Cable model of propagation failure at true deceleration (TD) sites. A: An overview of the simulated cable demonstrating the 4 regions and the interface between them, which were used to determine the site of propagation failure. Normal regions are represented by a relative sodium conductance (Nas) of 1 and a relative cable conductivity (Gs) of 1. B: The fast region has a Nas of 1.4 (40% increase above normal) and a Gs of 1.5. The slow region has a fixed Gs of 0.2 (80% reduction below normal) and the Nas is varied from 0.1 to 1.0. C: The fast region has identical parameters; however, Nas is fixed at 0.2 and Gs is varied from 0.1 to 1.0. In both panels (B and C), propagation failure (block) occurs when the safety factor is <1.