Electrogram Transition Patterns During Atrial Antitachycardia Pacing‐Mediated Termination

Figures

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  FIGURE 1. Study population and intracardiac electrogram availability. Flow diagram of patient selection and availability of stored intracardiac atrial electrograms (EGMs) for analysis. All screened patients (n = 199) had cardiac implantable electronic devices (CIEDs) capable of reactive atrial antitachycardia pacing (aATP); 80 were excluded because aATP was not activated. Of the remaining 119 with aATP activated, 36 had no device‐detected atrial tachyarrhythmias (ATAs) after activation and were excluded from EGM analysis, leaving 83 patients with device‐detected ATAs. Of these, 45 were excluded due to unavailable stored EGMs, yielding 38 patients with 1641 aATP‐terminated episodes available for analysis. *Of the 38 patients with available EGMs, 15 had prior catheter ablation for ATAs (ABL group; 410 episodes) and 23 had no prior ablation (No‐ABL group; 1231 episodes).

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  FIGURE 2. Definitions of atrial electrogram patterns and termination categories. (A) Representative examples of regular and irregular atrial electrograms. Regular atrial activity was characterized by discrete atrial deflections with consistent morphology and a stable baseline between deflections. Irregular atrial activity was characterized by polymorphic or fragmented atrial deflections and/or loss of temporal organization. Regularity was assessed by visual inspection of electrogram morphology with reference to atrial interval plots. (B) Representative interval plot showing immediate termination following atrial antitachycardia pacing (aATP). Immediate termination was defined as cessation of atrial tachyarrhythmia in fewer than 10 atrial beats following aATP delivery (dashed box). Episodes with immediate termination were not assessed for regularity because fewer than 10 beats were insufficient for regularity assessment.

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  FIGURE 3. aATP Success rate by ablation status. (A) Overall aATP success rate did not differ between the ABL and No‐ABL groups. Error bars indicate standard deviation. (B) In seven patients with follow‐up data before and after catheter ablation, aATP success rate increased after ablation. *Paired t‐test.

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  FIGURE 4. Electrogram regularity and transition patterns in aATP‐terminated atrial tachyarrhythmias. Distribution of electrogram regularity transition patterns at aATP‐mediated termination. At the episode level, the regular‐to‐irregular pattern was more common in the ABL group (39% vs. 22%); however, this difference was not significant after accounting for within‐patient clustering. R indicates regular atrial electrograms; I, irregular atrial electrograms; and T, immediate termination. The p‐value denotes comparison of the proportion of the regular‐to‐irregular transition pattern between groups. GEE, generalized estimating equations.

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  FIGURE 5. Representative Case of the Regular‐to‐Irregular Transition Pattern. (A) Device‐recorded intracardiac electrograms from an aATP‐terminated atrial tachyarrhythmia episode demonstrating a transition from regular atrial activity (blue box) to irregular atrial activity (red box) after aATP delivery, followed by termination. For definitions of regularity, see Figure 2A. (B) Corresponding interval plot from the same episode as panel A. Regularity classification was based on atrial electrogram morphology with reference to the atrial interval plot. A‐CL, atrial cycle length; A‐EGM, atrial electrogram; V‐EGM, ventricular electrogram.