What question did this study set out to answer?

To compare the reproducibility of clinically applicable measurement methods for defibrillation threshold (DFT) and upper limit of vulnerability (ULV).

December 1, 1996Pacing and Clinical Electrophysiology

Comparative Reproducibility of Defibrillation Threshold and Upper Limit of Vulnerability

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Why the study?

Does the determination of the upper limit of vulnerability (ULV) provide better reproducibility than the defibrillation threshold (DFT) in patients with a transvenous implantable cardioverter defibrillator?

Key Points

To compare the reproducibility of clinically applicable measurement methods for defibrillation threshold (DFT) and upper limit of vulnerability (ULV).
Prospectively evaluated 25 patients with transvenous implantable cardioverter defibrillators (Medtronic 7219D) during postoperative electrophysiological testing.
Measured DFT (lowest energy defibrillating after 10 s of VF) and ULV (lowest energy not inducing VF across three shocks delivered 0, 20, and 40 ms before the T-wave peak) twice using a three-step, midpoint protocol.
Assessed reproducibility by calculating Lin concordance coefficients between the first and second measurements.
Mean values were not significantly different between the first and second tests for DFT (10.1 ± 5.9 J vs 10.4 ± 5.8 J) or ULV (13.4 ± 6.8 J vs 13.8 ± 6.6 J).
The Lin concordance coefficient demonstrated significantly higher reproducibility for ULV compared to DFT (0.93, 95% CI 0.85–0.97 vs 0.64, 95% CI 0.33–0.82; P < 0.01).
Sample sizes required to detect 2 J, 3 J, and 4 J differences with 80% power (P < 0.05) were lower for ULV (15, 8, and 6) than for DFT (52, 24, and 15).

Structured PICO

Population

25 patients with a transvenous implantable cardioverter defibrillator (Medtronic 7219D) undergoing postoperative electrophysiological study

Intervention

Determination of upper limit of vulnerability (ULV) using a three-step, midpoint protocol for biphasic pulses

Comparator

Determination of defibrillation threshold (DFT) using a three-step, midpoint protocol for biphasic pulses

Outcome

Reproducibility of the measurement, assessed by Lin concordance coefficients for second determination versus first determinationsurrogate

The upper limit of vulnerability is a more reproducible measure than the single point defibrillation threshold for evaluating defibrillation efficacy.

Discussion

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Implication

ULV may offer more reproducible defibrillation assessment than DFT in transvenous ICD patients; leaves open whether adoption improves outcomes and requires prospective validation.

Cite This Study

Swerdlow et al. (1996) studied this question.

synapsesocial.com/papers/6a8ce49e748301e7973019dc https://doi.org/10.1111/j.1540-8159.1996.tb03285.x

Topics

Cardiac device therapy

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Implication

ULV may offer more reproducible defibrillation assessment than DFT in transvenous ICD patients; leaves open whether adoption improves outcomes and requires prospective validation.

Comparative Reproducibility of Defibrillation Threshold and Upper Limit of Vulnerability

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Topics

Comparative Reproducibility of Defibrillation Threshold and Upper Limit of Vulnerability

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Topics

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