Fine Ventricular Fibrillation Therapy Assurance Algorithm Failure From Low-Amplitude Far-Field Signals

Q: What is the clinical evidence from this study?

Study design: Case Report. Population: Nonischemic cardiomyopathy with CRT-D (n=1). Intervention: Targeted sensing vector reprogramming. Primary outcome: Inappropriate ICD shock.

Q: What does this research mean for the field?

Low-amplitude far-field electrogram signals can inappropriately trigger the VF Therapy Assurance algorithm during supraventricular tachycardia, causing detection zone collapse, discriminator suspension, and inappropriate ICD shocks. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Krunal Shukla; Conor Given; Roland-Austin Federico; Jason Bromirski; Kun Xiang

doi:10.1016/j.jaccas.2026.109675

August 18, 2026JACC Case ReportsOpen Access

Fine Ventricular Fibrillation Therapy Assurance Algorithm Failure From Low-Amplitude Far-Field Signals

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Key result

Sensing vector reprogramming prevents inappropriate VFTA-mediated ICD shocks caused by far-field supraventricular tachycardia signals.

n=1

Graphical abstract published by JACC Case Reports — Graphical abstract · Published by JACC Case Reports · CC BY-NC-ND 4.0

Why the study?

The VF Therapy Assurance algorithm may paradoxically trigger inappropriate ICD therapy in certain electrogram phenotypes due to low-amplitude far-field signals.

Key Points

To describe a failure mechanism of the VF Therapy Assurance algorithm leading to inappropriate defibrillator shocks and evaluate a programming strategy to prevent recurrence.
Interrogated a cardiac resynchronization therapy-defibrillator in a 53-year-old male with nonischemic cardiomyopathy who received a shock during light exertion.
Evaluated stored electrograms for far-field signal amplitude, rhythm discriminator behavior, and VF Therapy Assurance (VFTA) algorithm activation.
Reprogrammed the sensing configuration vector from Coil-Can to Tip-Can and monitored for recurrent inappropriate therapy.
Device interrogation demonstrated stable supraventricular tachycardia at 160 beats/min with low-amplitude far-field signals on the Coil-Can vector triggering VFTA activation.
VFTA engagement collapsed all programmed detection zones into a single therapy zone, suspended supraventricular tachycardia discriminators, and triggered an inappropriate shock after 6 beats meeting ventricular fibrillation criteria.
Vector reprogramming from Coil-Can to Tip-Can successfully eliminated inappropriate VFTA triggers with no recurrent inappropriate shocks observed during follow-up.

Study Design

Type

Case Report (n=1)

Structured PICO

P

Population

A 53-year-old man with a cardiac resynchronization therapy-defibrillator for nonischemic cardiomyopathy who received an inappropriate ICD shock.

I

Intervention

Reprogramming of the implantable cardioverter-defibrillator sensing vector from Coil-Can to Tip-Can.

O

Outcome

Recurrence of inappropriate ICD therapy.safety

Implication

Targeted sensing vector reprogramming can successfully mitigate inappropriate ICD shocks mediated by the VF Therapy Assurance algorithm during supraventricular tachycardia.

Abstract

BACKGROUND: The VF Therapy Assurance (VFTA) algorithm in Abbott implantable cardioverter-defibrillators (ICDs) enhances detection of fine ventricular fibrillation by utilizing far-field signals when near-field sensing is inadequate. However, this algorithm may paradoxically trigger inappropriate ICD therapy in certain electrogram phenotypes. CASE SUMMARY: A 53-year-old man with a cardiac resynchronization therapy-defibrillator for nonischemic cardiomyopathy presented after an ICD shock during light housework. Device interrogation revealed stable supraventricular tachycardia at 160 beats/min with low-amplitude far-field signals on the Coil-Can vector, triggering VFTA activation. This collapsed all detection zones into a single therapy zone, disabled supraventricular tachycardia discriminators, and delivered an inappropriate shock after only 6 beats meeting ventricular fibrillation criteria. The sensing vector was reprogrammed from Coil-Can to Tip-Can, with no recurrent inappropriate therapy on follow-up. DISCUSSION: Low-amplitude far-field signals can inappropriately activate VFTA, leading to zone collapse and discriminator suspension during supraventricular tachycardia, resulting in unwarranted therapy delivery. TAKE-HOME MESSAGE: Targeted sensing vector reprogramming may mitigate VFTA-mediated inappropriate shocks while preserving the algorithm's intended benefit for fine ventricular fibrillation detection.

Discussion

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Cite This Study

Shukla et al. (2026) conducted a case report in Nonischemic cardiomyopathy with CRT-D (n=1). Targeted sensing vector reprogramming was evaluated on Inappropriate ICD shock. Low-amplitude far-field signals during supraventricular tachycardia can inappropriately activate the VFTA algorithm, leading to unwarranted shocks that can be mitigated by sensing vector reprogramming.

synapsesocial.com/papers/6ad0fcbf15427f6a84040339 https://doi.org/10.1016/j.jaccas.2026.109675

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Fine Ventricular Fibrillation Therapy Assurance Algorithm Failure From Low-Amplitude Far-Field Signals

Key Points

Study Design

Structured PICO

Implication

Abstract

Discussion

Cite This Study

Fine Ventricular Fibrillation Therapy Assurance Algorithm Failure From Low-Amplitude Far-Field Signals

Key Points

Study Design

Structured PICO

Implication

Abstract

Discussion

Cite This Study

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