Arrhythmias & electrophysiology
Transseptal activation delta: A novel electrocardiographic criterion for left bundle branch capture
Authors' conclusion
TAD is a practical, reproducible intraoperative criterion for identifying left bundle branch capture. A 25-ms threshold supports the role of TAD as a confirmatory marker of conduction system capture with high specificity.
Study context
- Population
- Patients who underwent left bundle branch pacingn = 122 consecutive patients, 142 pacing observations (in 20 patients, measurements during septal pacing and after confirmation of left bundle branch capture), separate prospective validation cohort of 30 additional patients
- Exposure
- Transseptal activation delta (TAD) against left bundle branch capture defined by electrocardiographic criteria and dynamic pacing maneuvers
- Outcome
- Diagnostic accuracy of TAD threshold of ≥25 ms for left bundle branch capture
Methodological detailsconsecutive patients, separate prospective validation cohort
- Consecutive patients
- Separate prospective validation cohort
Main finding
As reported in the abstract
| Group | Sensitivity | Specificity | Overall diagnostic accuracy |
|---|---|---|---|
| Transseptal activation delta (TAD) | 78.9% | 95.7% | 84.5% |
Transseptal activation delta (TAD)
Sensitivity78.9%
Specificity95.7%
Overall diagnostic accuracy84.5%
Observational data: associations, not effects.
Further findings
Diagnostic performance in the prospective validation cohort
- This threshold retained diagnostic performance
Original publication
Transseptal activation delta: A novel electrocardiographic criterion for left bundle branch capture. Heart Rhythm. Published 25 May 2026. doi:10.
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