Defibrillation Testing During Implantable Cardioverter Defibrillator (ICD) Replacement: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Defibrillation Testing During Implantable Cardioverter Defibrillator (ICD) Replacement (NCT04206371), a na na study. The primary outcome is Rate of Defibrillator Electrical Integrity Dysfunction During Generator Replacement..

2. Clinical Question

In plain terms, the listed question is whether an abnormal shock impedance value was observed among patients undergoing threshold testing during ICD replacement. The endpoint is recorded as a count of participants, rather than as a continuous impedance measurement. The record names a secondary outcome, rate of lead malfunction, but does not provide its result either.

The study is not set up in the registry as a comparison of testing against no testing. Its single-group structure means that any recorded event count would describe the observed group, not establish what would have happened to comparable patients without testing. The registry record also does not report detailed eligibility criteria, baseline characteristics, or an explicit definition of an abnormal impedance value. These omissions limit how specifically the population and endpoint can be interpreted.

3. Trial Design

The registry describes a completed, single-group study of defibrillation testing during ICD replacement. Enrollment is listed as 143. The study start date is 2020-02-03, and primary completion is recorded as 2022-01-19. The listed phase is NA, allocation is NA, and masking is NONE. The record identifies CMC Ambroise Paré as the sponsor.

The intervention is defibrillator threshold testing, categorized as a diagnostic test. The arm description names defibrillation testing during ICD replacement, but gives no additional procedural details. The study summary says the evaluation concerns safety and clinical outcomes of systematic testing in patients with an indication for defibrillator replacement. Specific inclusion and exclusion criteria are not reported in the registry record.

The registry lists a primary outcome of rate of defibrillator electrical integrity dysfunction during generator replacement. Its measure is the number of participants with an abnormal shock impedance value, and its timeframe is 4 hours. Rate of lead malfunction is listed as a secondary outcome. Detailed definitions, assessment procedures, and results for these outcomes are not reported in the registry record.

Because the study is identified as single-group and no comparator is listed, it should be read as an observational description of outcomes in the tested group, not as a randomized treatment comparison. The registry record does not state the sample-size justification, a statistical analysis plan, or whether any interim analyses were planned or conducted. It also does not report participant flow, withdrawals, or the population included in any outcome analysis. The listed completion status indicates that the study is marked completed in the registry, but it does not itself supply outcome findings.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Procedure

Reasons for not completing this period:

12-Month Follow-up

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Rate of Defibrillator Electrical Integrity Dysfunction During Generator Replacement., measured over 4 hours.

The primary endpoint is a count of participants with an abnormal shock impedance value during generator replacement. The registry gives a 4-hour timeframe. This endpoint concerns a measure of electrical integrity around the replacement procedure; the record’s title refers to defibrillator electrical integrity dysfunction, while the endpoint description specifies abnormal shock impedance.

Counting participants with an event is a binary-outcome approach: for each person, the endpoint classification is whether the specified event was recorded or not. A count can be useful for describing how often a defined event occurs in a group. Its interpretation depends on a clear event definition, consistent measurement, and a known set of participants evaluated. The registry record does not provide the threshold used to define an abnormal value, the measurement protocol, or the number evaluated for this endpoint.

The stated timeframe helps specify when the outcome is assessed, but does not by itself explain how measurements were collected or adjudicated. Further endpoint definitions and operational details are not reported in the registry record. The outcome result is also not reported, so the observed count, proportion, and precision cannot be described from the registry information. The listed secondary outcome, rate of lead malfunction, addresses another aspect of device function, but its definition and result are likewise not reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods help connect an outcome definition to the data used to answer a clinical question. In this record, the primary outcome is expressed as a count of participants with an event. The registry does not list a statistical analysis for that endpoint, so the explanations below describe general concepts rather than methods confirmed as used in this study.

What does a participant count represent?

For a binary outcome, each person is classified according to whether the specified event occurred. The event count is the number classified as having the event; an event proportion also requires the number of people evaluated. These quantities answer different questions from a continuous measurement, such as the distribution of the measured impedance values themselves. The registry names a participant count and an abnormal-value event, but does not report the count, the evaluated denominator, or the underlying values.

A clear binary endpoint needs a reproducible rule for classifying a result as abnormal. The registry record does not report the numerical threshold or other operational criteria for that classification. Without those details, readers cannot assess whether the event definition is sufficiently specific to reproduce the outcome or compare it directly with another study’s definition.

How should uncertainty be understood?

In general, a point estimate describes the observed data, while a confidence interval conveys statistical uncertainty around an estimate under stated assumptions. Wider intervals indicate less precision, and narrower intervals indicate greater precision; neither, by itself, resolves possible biases in measurement or study design. No confidence interval or other uncertainty estimate for the primary outcome is reported in the registry record. Because the endpoint result is also absent, its precision cannot be discussed quantitatively.

General methods for binary outcomes may use a count and denominator to estimate an event proportion, with an interval that reflects the amount of information in the data. Such methods require the event definition, observed count, and analyzed denominator. They may also depend on assumptions about how observations were collected and whether participants contributed independent observations. The registry record does not provide enough information to identify an endpoint analysis or verify its assumptions.

Why does the single-group design matter?

A single-group study can describe what was observed among participants receiving the specified procedure. It does not directly estimate a contrast against a concurrent control group when no comparator group is listed. General statistical methods cannot create that missing comparison: adjustment or modeling requires relevant measured data and a defined analysis, neither of which is reported for this endpoint. Therefore, an event count, if available, would describe the group rather than establish a causal effect of testing.

Allocation is listed as NA, masking as NONE, and the model as SINGLE GROUP. These registry descriptions do not establish additional details about implementation, outcome assessment, or participant selection. The record does not report whether outcome assessors were independent, whether measurements were blinded, or how potential sources of bias were handled. Those items should not be inferred from the design labels alone.

What can planning calculations tell readers?

Sample-size calculations are planning tools. In general, they describe how many participants a proposed design might require under specified assumptions about the effect to detect, significance level, power, allocation, and statistical model. Such calculations are not observed outcomes and are not evidence that a study had a particular probability of finding an effect after the data were collected.

The registry record does not report the study’s own sample-size justification or statistical plan. The stated planning assumptions describe an illustration based on an observed effect, two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. They also distinguish participant counts per arm from total event counts for time-to-event methods. Those assumptions do not describe this study’s single-group design as a randomized comparison, and no corresponding planning estimates or observed primary effect are reported in the registry record. They should not be treated as the trial’s protocol or as observed power.

Over-dispersion is a general concern when outcome variability exceeds what a simple model assumes. If it is present, a model that assumes less variability may understate uncertainty. This concept is relevant to some count-data analyses, but the registry describes the primary measure as a binary participant count and does not report a count model, evidence of over-dispersion, or a model-based analysis. No claim about over-dispersion in this study can therefore be made.

Likewise, the registry does not report hypothesis tests, covariate adjustment, confidence intervals, or statistical software for the primary endpoint. These are not details that can be reconstructed from the endpoint title, enrollment, or adverse-event entries. The available information supports an explanation of the outcome’s form and design context, but not a replication or appraisal of an unreported analysis.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Defibrillation Testing During ICD Replacment")
n      <- c(139)
events <- c(1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Defibrillation Testing During ICD Replacment  139  1  0.7  0.0  3.9  0.1  4.0  0.2  3.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and a secondary outcome. The primary outcome concerns participants with an abnormal shock impedance value during generator replacement; the secondary outcome is rate of lead malfunction. Considering multiple outcomes can raise a general multiplicity question: if several hypotheses are tested, the chance of at least one apparently unusual result can increase unless the analysis plan addresses that issue.

The registry record does not report a multiplicity strategy, a hierarchy among secondary measures, or a statistical analysis plan. It does not state whether outcomes were tested formally or whether any adjustment was planned. The primary outcome result and the secondary outcome result are not reported, so the consequences of any testing choices cannot be assessed.

Missing-data handling is also not reported. The record does not state how many participants had each outcome assessed, whether any measurements were unavailable, how missing observations were classified, or whether a sensitivity analysis was conducted. Enrollment of 143 should not be assumed to equal the denominator used for every endpoint. In general, missingness can affect an estimate if the availability of outcome data is related to participants’ characteristics or outcomes; the registry does not provide information to evaluate that possibility.

The analysis population is not reported in the registry record. There is no description of whether all enrolled participants, only those who underwent testing, or another defined group contributed to the endpoint analysis. The registry records 0 analyses, which means no analysis entry is listed; it does not establish what analyses may have been performed elsewhere. Without an analysis population, missing-data rules, and outcome results, neither the completeness nor the analytic treatment of the endpoint data can be assessed.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The registry’s adverse-event entry for the defibrillation testing group lists 143 at risk for serious adverse events and 0 affected. It also lists 143 at risk for other adverse events and 0 affected, with 0 deaths. These are the posted safety counts for the named group.

A recorded zero means that no affected participants are listed in that registry entry. It is not proof that the underlying event risk is absent. In general, a zero count can still be compatible with some uncertainty about the rate that might occur in a broader population, particularly when event information is limited. No interval estimate for these safety counts is reported in the registry record.

The adverse-event figures should not be read as the primary endpoint result. Abnormal shock impedance is the listed primary measure, while the safety entry reports adverse events and deaths. The record does not state whether the adverse-event categories were collected over the same timeframe as the primary endpoint or whether every type of event was included. The serious-event terms list is empty, so no specific serious-event terms are listed in the registry record.

13. What the Result Does, and Does Not, Mean

The study record identifies a clinical question about defibrillation threshold testing during ICD replacement and specifies an endpoint based on abnormal shock impedance within 4 hours. It also records that the study is completed and lists enrollment of 143. These details describe the study’s scope and design, but they do not provide the primary endpoint result.

Without the observed endpoint count and the number assessed, readers cannot determine the recorded frequency of abnormal shock impedance or how precisely that frequency was estimated. The registry also does not provide a result for lead malfunction. The adverse-event entries list zero affected participants for serious and other adverse events and zero deaths, but those counts do not substitute for the primary or secondary outcome findings.

The single-group design sets an additional boundary on interpretation. Even if an outcome count were available, it would describe the participants in the tested group. With no comparator listed, the record cannot directly show how outcomes compare with a similar group not undergoing testing. In general, a comparison is needed to distinguish an intervention-related difference from other explanations; this study record does not present such a comparison.

The record does not report detailed participant characteristics, eligibility rules, endpoint criteria, missing-data procedures, or a statistical analysis plan. These omissions limit assessment of who the findings might represent and how robust an estimate would be. They do not establish that such information is unavailable elsewhere, only that it is not reported in the registry record.

Accordingly, the result should be described as unreported rather than interpreted as favorable, unfavorable, or conclusive. The registry documents the study question, design, endpoint, timeframe, and adverse-event counts. It does not supply the quantitative primary outcome findings needed to characterize the observed electrical integrity outcome.

14. Why This Trial Matters Statistically

This study is statistically notable for the gap between a clearly named clinical endpoint and the absence of a posted result for that endpoint. The registry specifies a participant count for abnormal shock impedance and a 4-hour assessment timeframe. Without the observed count and assessed denominator, however, readers cannot estimate the event frequency or its uncertainty. A well-defined question is not the same as a reported answer.

The single-group design also makes the distinction between describing and comparing especially important. A group’s event count can describe what was recorded during a procedure, but it does not by itself quantify the difference that would be expected under an alternative approach. The registry lists no comparator, so causal or comparative interpretation is outside what this record can establish.

Safety summaries need similar care. The record lists zero serious adverse events, zero other adverse events, and zero deaths in the group, but these entries do not establish that no risk exists. They are observed counts in the registry entry, and no uncertainty estimates or broader safety assessment are reported.

For clinical researchers, the record illustrates why outcome definitions, denominators, analysis populations, missing-data rules, and uncertainty estimates matter alongside enrollment and completion status. Those elements allow readers to understand what was measured, how much information supports an estimate, and how far the findings can be generalized. Several of these details are not reported in the registry record.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main trial-specific limitation in interpreting this record is that it does not report the primary outcome result. The registry names a count of participants with abnormal shock impedance during a 4-hour timeframe, but gives neither an observed count nor the number assessed for that endpoint. The secondary outcome, rate of lead malfunction, is also listed without a reported result.

The registry identifies the study as single-group and lists no comparator. Consequently, the record cannot support a direct comparison with an alternative strategy. Allocation is listed as NA, and the record does not describe a control group or a randomized comparison. It would be inappropriate to treat the adverse-event counts as a comparative estimate.

Important interpretive details are not reported in the registry record, including eligibility criteria, participant characteristics, the operational definition of abnormal impedance, outcome assessment procedures, analysis populations, and missing-data handling. The registry also does not report the sample-size justification, statistical analysis plan, or any primary endpoint analysis. These gaps limit appraisal of endpoint reproducibility, precision, and the possibility of bias.

The adverse-event entry lists zero serious events, zero other events, and zero deaths, but the record does not provide uncertainty estimates or specify whether the adverse-event collection period matches the primary endpoint timeframe. The registry’s completed status does not fill these reporting gaps. These limitations concern what can be interpreted from the registry record, and do not establish whether additional information exists outside it.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Defibrillation Testing During Implantable Cardioverter Defibrillator (ICD) Replacement — NCT04206371.
• Registry record last updated 2026-06-03; status last verified 2023-09.
• Results first posted 2026-05-14.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes a completed, single-group study of defibrillator threshold testing during ICD replacement, sponsored by CMC Ambroise Paré. Enrollment is listed as 143; the study start date is 2020-02-03 and primary completion is 2022-01-19. The intervention is categorized as a diagnostic test.

The primary endpoint is the number of participants with an abnormal shock impedance value during generator replacement, with a timeframe of 4 hours. Rate of lead malfunction is listed as a secondary outcome. The registry does not report results for either outcome or list any analyses. It reports 0 serious adverse events, 0 other adverse events, and 0 deaths in the group.

No comparator is listed. Detailed eligibility criteria, analysis populations, missing-data procedures, and the statistical analysis plan are not reported in the registry record. The primary endpoint findings therefore cannot be quantitatively interpreted from this record.