Isochronal Versus Electrogram-Based Conduction Velocity Estimation to Predict Inducible Monomorphic…

Cohort studyCirculation. Arrhythmia and electrophysiology· Aug 2026

Isochronal Versus Electrogram-Based Conduction Velocity Estimation to Predict Inducible Monomorphic Ventricular Tachycardia in Repaired Tetralogy of Fallot.

Edward T O'Leary, Victor Waldmann, Francis Bessière … Jeremy P Moore

Congenital Cardiac SurgeryCohort studyDiagnosisQ1IF 6.0

Higher isochronal conduction velocity index linked to lower odds of inducible ventricular tachycardia

Isochronal Versus Electrogram-Based Conduction Velocity Estimation to Predict Inducible Monomorphic Ventricular Tachycardia in Repaired Tetralogy of Fallot.

Edward T O'Leary … Jeremy P Moore

Circulation · Aug 2026 · Q1 in General Medicine

Background

Isthmus conduction velocity (conduction velocity) predicts ventricular tachycardia risk in tetralogy of Fallot and traditionally is calculated using electrogram-based methods (electrogram conduction velocity index [EGM-CVi]).

Methods

Retrospective cohort subanalysis of the CATAPULT-TOF registry (Catheter Ablation of Ventricular Tachycardia Before Transcatheter Pulmonary Valve Replacement in Repaired Tetralogy of Fallot).

Results

Each rise in this conduction velocity index sharply lowers odds of inducible ventricular tachycardia

OR 0.14 (95% CI 0.04 to 0.40)

CI excludes the null - significant

More results

Seventy patients with tetralogy of Fallot underwent pretranscatheter pulmonary valve replacement electrophysiology study at a median age of 40 (interquartile range, 24.8-51) years.

Median ISO-CVi was lower in those with versus without monomorphic ventricular tachycardia (0.17 versus 0.30 m/s; P <0.001).

More results

Median EGM-CVi did not differ between groups (0.43 versus 0.70 m/s; P =0.055).

Coefficients of variation were higher for EGM-CVi (79%) than ISO-CVi (45%).

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Conclusion · 1 of 2

ISO-CVi strongly associates with inducible monomorphic ventricular tachycardia and is measured with less variability than legacy EGM-CVi methods in a real-world sample.

Conclusion · 2 of 2

If external validity is confirmed, ISO-CVi may represent a more standardized method of isthmus conduction velocity estimation that could be broadly implemented across centers.

Isochronal Versus Electrogram-Based Conduction Velocity Estimation to Predict Inducible Monomorphic Ventricular Tachycardia in Repaired Tetralogy of Fallot.

Isochronal Versus Electrogram-Based Conduction Velocity Estimation to Predict Inducible Monomorphic Ventricular Tachycardia in Repaired Tetralogy of Fallot.

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