June 1, 1996Journal of Cardiovascular Electrophysiology
Early Postoperative Rise in Defibrillation Threshold in Patients with Nonthoracotomy Defibrillation Lead Systems:
Why the study?
Does biphasic shock waveform prevent early postimplantation defibrillation threshold rise in patients with non-thoracotomy defibrillation lead systems compared to monophasic shock waveform?
Population
146 patients with a non-thoracotomy defibrillation lead (NTL) system
Comparison
Biphasic shock waveforms vs Monophasic shock waveforms
Design
Cohort
Follow-up
mean 49 +/- 22 days
Authors
Discussion
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Member takes
Implication
Biphasic waveform was associated with fewer early DFT rises; leaves open whether this supports preferential use in nonthoracotomy systems.
Key Points
- To determine predictors of early postimplantation rises in defibrillation threshold (DFT) and compare the effects of monophasic versus biphasic shock waveforms in patients with nonthoracotomy lead systems.
- Evaluated serial DFT measurements at implantation, prior to hospital discharge (mean 4 ± 3 days), and at follow-up (mean 49 ± 22 days) in N=146 patients receiving nonthoracotomy lead systems.
- Assessed clinical and procedural variables for association with a clinically important DFT rise, defined as an increase of ≥2 energy steps (≥5 J total).
- Tested a consecutive crossover subgroup of N=18 patients undergoing serial DFT evaluations with both monophasic and biphasic waveforms.
- A clinically important early DFT rise occurred in 33% of patients overall (48/146), with monophasic shock waveform identified as the only independent predictor (F = 18, P < 0.001).
- The incidence of a clinically important DFT rise was significantly higher in the monophasic group (53%, 42/79) than in the biphasic group (9%, 6/67).
- In the subgroup tested with both waveforms (N=18), monophasic shocks demonstrated a higher rate of clinically important DFT rise (50%, 9/18) compared to biphasic shocks (17%, 3/18; P = 0.05).
Structured PICO
Does biphasic shock waveform prevent early postimplantation defibrillation threshold rise in patients with non-thoracotomy defibrillation lead systems compared to monophasic shock waveform?
P
Population
146 patients with a non-thoracotomy defibrillation lead (NTL) system
I
Intervention
Biphasic shock waveforms
C
Comparator
Monophasic shock waveforms
O
Outcome
Clinically important early postimplantation defibrillation threshold (DFT) rise (defined as a rise of >= 2 energy steps; >= 5 J total)surrogate
Biphasic shock waveforms significantly attenuate the incidence of early postimplantation defibrillation threshold rise compared to monophasic waveforms in patients with non-thoracotomy lead systems.
Cite This Study
Schwartzman et al. (1996) studied this question.