Arrhythmias & electrophysiology
Microvolt Activation Alternans Identifies Conduction Velocity Heterogeneity and the Entrance Site of Ischemic Ventricular Tachycardia
Authors' conclusion
Microvolt intra-QRS AA in the bipolar EGM is a marker of CV heterogeneity that associates with the VT entrance and may guide VT ablation. Surface QRS alternans is a manifestation of intra-QRS AA and may inform risk stratification.
Study context
- Population
- Patients with ischemic cardiomyopathy undergoing intraoperative mapping during ventricular pacing and induced ventricular tachycardia (VT)
- Participants
- 9 patients
- Comparison
- Intra-QRS activation alternans (AA) at the entrance of the VT circuit compared with remote regions
- Outcome
- Presence of AA
Methodological detailsin silico modeling
- In silico modeling
Main finding
As reported in the abstract
Intra-QRS and post-QRS AA present
8 of 9 patients
Further findings
| Outcome | OR (95% CI) | P value | |
|---|---|---|---|
| Presence of intra-QRS AAVT circuit entrance vs Remote regions | 6.8 (3.7–12.5) | P < 0.001 | |
| 0.050.21520Odds ratio (log scale) |
| Outcome | Magnitude increase (μV) (95% CI) | P value | |
|---|---|---|---|
| Intra-QRS AA magnitude per 0.1 increase in CV heterogeneity | 31 (3-59 μV) | P = 0.032 | |
| −50050100Difference, μV (linear scale) |
| Outcome | Intra-QRS AA | Post-QRS AA | VT circuit entrance | Remote regions | P value | |
|---|---|---|---|---|---|---|
| AA frequencyIntra-QRS AA vs Post-QRS AA | median 4.6% (IQR 2.8%–8.3%) | median 3.5% (IQR 1.0%–4.7%) | Not reported in the abstract | Not reported in the abstract | P = 0.77 | VT circuit entrance, Remote regions: not reported in the abstract |
| AA magnitudeIntra-QRS AA vs Post-QRS AA | median 192 (IQR 72-246 μV) μV | median 470 (IQR 270-601 μV) μV | Not reported in the abstract | Not reported in the abstract | P = 0.158 | VT circuit entrance, Remote regions: not reported in the abstract |
- Intra-QRS AA magnitude per 0.1 increase in conduction velocity (CV) heterogeneity: CV heterogeneity was the primary determinant of intra-QRS AA magnitude
Correlation of intra-QRS AA magnitude with surface QRS alternans magnitude
- R
- 0.92
- P
- P = 0.001
Computer modeling
- AA sites representing <1-mm channels with 2:1 conduction block
Original publication
Microvolt Activation Alternans Identifies Conduction Velocity Heterogeneity and the Entrance Site of Ischemic Ventricular Tachycardia. JACC Clin Electrophysiol. Published 16 April 2025. doi:10.
Summarised from the published abstract; every number is checked against it