Simultaneous Whole-Chamber Non-contact Mapping of Highest Dominant Frequency Sites During Persistent Atrial Fibrillation: A Prospective Ablation Study

Figures

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  FIGURE 1. Diagram of the workflow for ablation targets identification. (A) St. Jude Ensite: left atrial geometry isopotential map exported from Ensite Velocity System. (B) Array data is imported into a bespoke MATLAB user interface. QRST subtraction: Electrograms using one ECG lead as reference. (C) FFT and DF detection: power spectrum of the current non-contact atrial signal and DF identification (D) 3D and 2D DF/HDF maps: MATLAB reconstructed 3D Atrial geometry with color-coded DF/HDF and transformation to 2D uniform grid. (E) The top panel shows an antero-posterior view of the LA, with the region hosting HDF for a single 4 s time window highlighted in purple. The pink dots indicate the HDF spatial centers for all time windows. For better intraprocedural clarity, the bottom panel shows only the HDF spatial centers (white dots) identified across all the mapped time windows. (F) Identifying and ablating HDF regions. These are transcribed into the Velocity 3D mapping system and targeted with ablation (red dots). Yellow dots represent anatomical marker points. FFT, fast Fourier transform; HDF, highest dominant frequency.

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  FIGURE 2. Patterns of pre-ablation isopotential map behavior in and around HDF regions. For each case, the temporal sequence is from left to right and top to bottom. The timing of each frame relative to the first is given in ms. Each image is centered around an area that was subsequently ablated based upon the presence of HDF spatial centers. Purple areas on the map represent atrial myocardium where local activation is absent, as defined by a local vEGM (virtual electrogram) amplitude above –0.28 mV. Voltages of –0.53 mV or less display as white, with the remainder of the color scale defining intermediate values. The appearance and trajectory of color around the maps were used to define the following wavefront activation patterns: (A) Rotor-like behavior, seen on the LA roof. The final panel shows an isochronal map of the area during this period, confirming rotational activity. AFCL was not significant altered by ablation in this region. (see also Supplementary Video 1). (B) Activation passes through the posterior wall of the LA three times consecutively (see Supplementary Video 2) within a single TQ period, but ablation here did not alter AFCL. (C) A wavefront is seen to split into two…

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  FIGURE 3. Examples of AF termination following ablation of a region of highest dominant frequency. (A) Patient 5. The white arrow indicates the point of transition from AF to a persistent organized atrial tachyarrhythmia. (B) Patient 7. The left atrium is silent with no coronary sinus (CS) signal at baseline, but with ECG evidence of ongoing AF. Pacing from the ablation (Abl) catheter captures the CS with organized distal to proximal activation.

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  FIGURE 4. (A) The four HDF targeted ablation regions from patient 5 are shown. The color scale corresponds to occurrences of HDF at the given spatial location. Individual lesions are labeled according to their impact on AFCL, with a change of 10 ms or more considered significant. Yellow triangles indicate the location of HDF spatial centers. (B) Changes in AFCL for each consecutive region of HDF-guided LA ablation. Lines are labeled with their respective patient number. Case progression is from left to right. *, patients in whom sinus rhythm was restored without the need for electrical cardioversion; AFCL, atrial fibrillation cycle length; HDF, highest dominant frequency; MV, mitral valve annular locations; LUPV, left upper pulmonary vein; RUPV, right upper pulmonary vein; RLPV, right lower pulmonary vein.

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  FIGURE 5. Spectral characteristics of HDF-targeted ablation regions compared with the AFCL response to ablation of that region. (A) HDF counts. (B) HRI counts. (C) HDF + HRI concurrence counts. Values shown are median ± interquartile range. DIS – ablation lesions resulting in an AFCL decrease/disorganization of 10 ms or more; EQU – ablation lesions resulting in equivocal change in AFCL of between –9 and + 9 ms; ORG – ablation lesions resulting in AFCL increase/organization of 10 ms or more; * indicates a statistically significant difference when compared with the corresponding DIS group after correction for multiple comparisons.

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  FIGURE 6. (A) Comparing numbers (mean and SD) of focal activation events with the AFCL response to ablation of that region; *p < 0.05 for Kendall’s correlation between the variables. (B) Counts of focal extinction and activation events within the same regions. Line of best fit and confidence intervals by linear regression are shown (p < 0.0001).

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  FIGURE 7. Demonstrating the temporal consistency of focal activation events. (A) In one patient, for each consecutive TQ interval, the number of observed focal activation events for one ablated region is shown by the solid line. The dotted line indicates the MMax (moving maximum) for the region, and an example of the derivation of diffMMax is shown. (B) The variation in the consistency of focal activation as measured by diffMMax (filled circles) and diffMMin (unfilled circles) across all 51 lesions from all 10 patients are shown. See main text for definitions.