June 1, 1994Pacing and Clinical Electrophysiology
Early Postoperative Increase in Defibrillation Threshold with Nonthoracotomy System in Humans
Key result
In patients with a multilead nonthoracotomy ICD system, the defibrillation threshold significantly increased 2-8 days postoperatively (22.7 J vs 16.9 J at implant; P<0.05) before returning to baseline.
Why the study?
Does the defibrillation threshold change early postoperatively compared to implant in patients receiving a nonthoracotomy ICD system?
Population
15 patients undergoing implantation of an implantable cardioverter defibrillator, predominantly using a…
Comparison
Defibrillation threshold testing at 2-8 days… vs Defibrillation threshold at the time of implant.
Design
Cohort
Follow-up
4-6 weeks
Authors
Discussion
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Implication
May warrant early postoperative DFT vigilance in nonthoracotomy ICDs; leaves open validation in contemporary systems and outcome impact.
Key Points
- This research aims to assess the stability of the defibrillation threshold (DFT) after the implantation of a nonthoracotomy system.
- Evaluated 15 patients with a three-lead nonthoracotomy system at implant, 2-8 days, and 4-6 weeks postoperation.
- DFTs measured using shocks starting at 18 joules or 2-4 joules above implant DFT.
- Shocks delivered in increments or decrements of 2-4 joules.
- DFT significantly higher postoperatively (22.7 +/- 7.0 J) compared to implant (16.9 +/- 3.9 J; P < 0.05).
- In patients assessed at all three intervals, DFT increased postoperatively (22.8 +/- 8.3 J) and returned to baseline by 4-6 weeks (16 +/- 7.1 J; P = N.S.).
- Findings suggest that monitoring DFT is crucial for energy output programming post-implant.
Study Design
Type
Cohort (n=15)
Structured PICO
Does the defibrillation threshold change early postoperatively compared to implant in patients receiving a nonthoracotomy ICD system?
P
Population
15 patients evaluated for defibrillation threshold stability early after implantation of an implantable cardioverter defibrillator, followed for up to 4-6 weeks.
E
Exposure
Defibrillation threshold (DFT) testing at 2-8 days postoperation and 4-6 weeks later.
C
Comparator
Defibrillation threshold (DFT) at the time of implant.
O
Outcome
Defibrillation threshold (DFT), defined as the lowest energy shock resulting in successful defibrillation.surrogate
Main Result
Absolute Event Rate: 22.7% vs 16.9%
p-value: p=<0.05
Defibrillation thresholds transiently increase early after nonthoracotomy ICD implantation before returning to baseline by 4-6 weeks, which has important implications for programming energy output.
Cite This Study
Hsia et al. (1994) conducted a cohort in Implantable cardioverter defibrillator implantation (n=15). Implantable cardioverter defibrillator implantation vs. Baseline (at implant) was evaluated on Defibrillation threshold (DFT) at 2-8 days postoperation (p=<0.05). In patients with a multilead nonthoracotomy ICD system, the defibrillation threshold significantly increased 2-8 days postoperatively (22.7 J vs 16.9 J at implant; P<0.05) before returning to baseline.