Arrhythmias & electrophysiologyCohort study
Ultrasound-guided parasternal tunneling during intermuscular subcutaneous implantable cardioverter-defibrillator implantation is associated with lower shock impedance and more favorable implant geometry
- retrospective single-center cohort study
Authors' conclusion
FUSIM strategy was associated with lower high-voltage shock impedance and more favorable radiographic parameters. A prospective multicenter evaluation is warranted to determine whether FUSIM reduces the need for routine VF conversion testing.
Study context
- Population
- Adults undergoing subcutaneous implantable cardioverter-defibrillator implantation (January 1, 2014, to December 2024)Ventricular fibrillation (VF) conversion testing attempted in 214 (80.8%), high-voltage shock impedance available in 186, quantitative radiographic measurements available in 225 · SC 87 · FIM 118 · FUSIM 60
- Participants
- 265 adults
- Exposure
- FUSIM vs conventional approaches
- SCn = 87
- FIMn = 118
- FUSIMn = 60
- Outcome
- High-voltage shock impedance during VF conversion testing
Main finding
As reported in the abstract
FUSIM vs SC: P < 0.001 · FUSIM vs FIM: P < 0.01
Observational data: associations, not effects.
Further findings
Impedance ≥70 Ω
First-shock conversion failure at 65 J
- 3 of 214 (1.4%), all in the SC group
- 3 of 214 (1.4%)
PRAETORIAN scores and coil-sternum distance
- FUSIM group showed lower coil-sternum distance
- P < 0.01
- Intermuscular (IM) approaches had lower PRAETORIAN scores than SC
- radiographic measures assessed in a consecutive single-operator subset
Original publication
Ultrasound-guided parasternal tunneling during intermuscular subcutaneous implantable cardioverter-defibrillator implantation is associated with lower shock impedance and more favorable implant geometry. Heart Rhythm. Published 30 March 2026. doi:10.1016/j.hrthm.2026.03.1909
Summarised from the published abstract; every number is checked against it