Antitachycardia Pacing for Fast Scar-Mediated Ventricular Tachycardia Across Non-Ischemic Cardiomyopathies: A Case Series

Figures

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  Figure 1. Device programming and stored electrograms demonstrating ATP termination of fast monomorphic VT in Case 1: (A) Implantable cardioverter-defibrillator programming at the time of the episode. The device was programmed in DDD mode with a base rate of 50 beats/min. The ventricular therapy zones included a VT-1 monitor zone beginning at 155 beats/min, a VT-2 therapy zone beginning at 179 beats/min with antitachycardia pacing followed by shocks, and a VF zone beginning at 222 beats/min with ATP during capacitor charging followed by high-energy shocks if required. Antitachycardia pacing was programmed as burst pacing with 8 stimuli at 85% of the tachycardia cycle length; (B) Stored intracardiac electrograms demonstrating a regular fast ventricular tachyarrhythmia classified in the VF zone by rate. The stable morphology and cycle length are consistent with fast monomorphic VT and (C) ATP during charging terminates the episode, restoring sinus/DDD rhythm and avoiding shock delivery.

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  Figure 2. ATP termination of very fast monomorphic VT in Case 2. Stored ICD electrograms from the ventricular near-field and shock-channel electrograms demonstrate detection of a regular fast ventricular tachyarrhythmia with cycle lengths in the VF zone. Despite rate-based VF-zone classification, the stable electrogram morphology and cycle-length organization are consistent with very fast monomorphic VT. Burst ATP is delivered, followed by prompt termination of the episode and return to sensed/paced ventricular rhythm without shock delivery.

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  Figure 3. Recurrent fast VT episodes successfully treated by ATP in Case 3: (A) Device episode summary showing recurrent ventricular tachyarrhythmia episodes, including sustained VT-2 events successfully terminated by ATP without shock delivery, and (B) Representative stored intracardiac electrograms demonstrating a regular fast ventricular tachyarrhythmia with a cycle length of approximately 245 ms, detected in the fast VT/VF range. Delivery of ATP/stimulation during the episode terminates the tachycardia and restores a slower ventricular rhythm.

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  Figure 4. Device programming and recurrent ATP-terminated VT in Case 4: (A) CRT-D zone configuration showing VT-1 monitor zone, VT-2 therapy zone, and VF zone with ATP before shock therapy. Burst ATP was programmed with 8 stimuli at 85% of the tachycardia cycle length; (B) Surface ECG during wide-complex tachycardia consistent with sustained monomorphic VT; (C) Representative stored intracardiac electrogram showing VT-2 at 190 beats/min with successful termination by ATP and restoration of ventricular sensed rhythm, and (D) Episode summary demonstrating clustered VT-2 episodes on the same day, all successfully treated with ATP without shock delivery.

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  Figure 5. Shock-free electrical storm treated by ATP in Case 5. Remote monitoring/device summary showing multiple alerts for ATP therapy delivered to terminate ventricular tachyarrhythmia over a 4-day period. The representative stored electrogram demonstrates onset of a regular ventricular tachycardia with ventricular cycle lengths in the fast VT range, followed by ATP-mediated termination without shock delivery.