EGM Analysis in Idiopathic Outflow Tract Ventricular Arrhythmia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for EGM Analysis in Idiopathic Outflow Tract Ventricular Arrhythmia (NCT02722577), a registered phase not stated study. The primary outcome is Percent of Ablation Targets With Termination of the Clinical Ventricular Arrhythmia After RF Energy Delivery.

2. Clinical Question

3. Trial Design

This is a completed study titled “EGM Analysis in Idiopathic Outflow Tract Ventricular Arrhythmia.” Its stated purpose is to investigate the value of unipolar and bipolar electrograms for predicting a successful ablation site during ablation of idiopathic outflow tract ventricular arrhythmia. Radio-frequency ablation is the listed procedure. The registry gives an enrollment of 20 participants and identifies ventricular outflow tract tachycardia as the condition.

The record lists a start date of 2016-03 and a primary completion date of 2017-05, with status marked COMPLETED. These dates describe the registry record’s study milestones; they do not establish when each participant was treated or followed. A more detailed schedule is not reported in the registry record.

The study is not described as a randomized comparison. Allocation is not stated, and the record flags that any arms are not a like-for-like control comparison. The number and definition of arms, any assignment procedure, and the presence or nature of a control group are not reported in the registry record. Therefore, the record does not support an interpretation based on randomized between-group differences.

The registry lists one primary outcome measure, concerning termination of the clinical ventricular arrhythmia after RF energy delivery. It gives an intraoperative timeframe described as an average of 2 hours. The primary measure’s title refers to a percentage of targets, whereas its unit is participants and its parameter is a count of participants. The record does not clarify the analysis unit or provide a numerical result. A trial-specific sample-size justification, detailed statistical plan, and participant flow are not reported in the registry record.

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.

Before assignment: Presence of clinical arrhythmia during the ablation procedure is a requirement for the study protocol and can not be guaranteed at the time of enrollment. 2 of the patients who have consented did not have clinical arrhythmia present at the time of the ablation procedure and were therefore not included in the study.

Overall Study

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 Percent of Ablation Targets With Termination of the Clinical Ventricular Arrhythmia After RF Energy Delivery, measured over Intraoperative, an average of 2 hours.

The primary endpoint is titled “Percent of Ablation Targets With Termination of the Clinical Ventricular Arrhythmia After RF Energy Delivery.” It concerns whether the clinical ventricular arrhythmia terminates after RF energy is delivered at an ablation target. The stated timeframe is intraoperative, with an average of 2 hours. The endpoint description itself is empty in the registry record.

This kind of endpoint is intended to capture an immediate procedural event associated with a target site. In general, an endpoint should define what is counted, the unit of observation, the event criteria, and the time window. Clear definitions matter because a percentage of targets and a count of participants are not necessarily interchangeable: a participant might contribute more than one target, depending on the study’s procedures. That possibility is a general measurement issue, not a reported feature of this study.

For this record, the title uses “percent of ablation targets,” but the listed unit is participants and the parameter is a count of participants. The registry does not explain how these descriptions were reconciled or whether each participant contributed one target or more than one. It also does not report how many targets or participants had termination. Consequently, the endpoint’s intended clinical event can be described, but its operational definition and observed frequency cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends first on a clearly defined question, observation unit, endpoint, and comparison. Here, the stated question concerns whether unipolar and bipolar electrograms can predict an ablation site associated with termination of the clinical ventricular arrhythmia after RF energy delivery. The endpoint title refers to ablation targets, while the listed unit is participants and the parameter is a count of participants. The registry record does not explain that difference. This ambiguity matters because the count and uncertainty calculations depend on what one observation represents.

What does a binary endpoint mean?

General explanation: a binary endpoint classifies an observation into one of two categories, such as whether a specified event occurred or did not occur. The record identifies the outcome type as binary and describes the event as termination after RF energy delivery. A binary result is commonly reported as the number of observations meeting the event definition alongside the number assessed. For a percentage, the denominator and the unit being counted must also be clear. The registry record does not post the event count, denominator for the primary outcome, or a numerical percentage.

The distinction between a participant and an ablation target is consequential in general. If more than one target can be assessed for a participant, target-level observations within one participant may be related rather than independent. An analysis that treats related observations as independent can give misleading uncertainty. This is a general statistical consideration only; the registry does not report how many targets were assessed per participant or whether repeated target observations occurred.

What would an estimate and confidence interval tell a reader?

General explanation: an estimate describes the observed result in a sample, while a confidence interval communicates the uncertainty around that estimate under the assumptions of the analysis. A narrower interval indicates greater precision under those assumptions; a wider interval indicates less precision. Neither is a guarantee about an individual participant or a direct statement of clinical importance. No primary-outcome estimate or confidence interval is reported in the registry record, so neither the observed frequency nor its precision can be evaluated.

Predictive performance can require more than a count of endpoint events. General measures may assess how well a predictor distinguishes observations with and without an outcome, whether predicted risks agree with observed frequencies, and how useful a threshold is for identifying a target. The exact measure depends on the question and data structure. No predictive-performance statistic, threshold, validation procedure, or model is reported in the registry record. The study’s stated aim alone does not establish that any particular predictive analysis was performed.

Why does the comparison structure matter?

General explanation: randomized comparisons use an assignment process intended to make groups comparable on average, while nonrandomized or within-procedure comparisons can be affected by how sites, measurements, or participants are selected. The registry does not state an allocation method and flags that arms are not a like-for-like control comparison. It does not describe a formal comparison of the electrogram measures. A difference between groups or categories, if one were reported, would therefore need to be interpreted in light of the actual design and analysis rather than assumed to be a randomized treatment effect.

The registry’s sample-size assumptions describe planning illustrations based on an observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. These are assumptions for illustrations, not reported features of the trial’s own design. The record does not report a trial-specific sample-size justification or the assumptions used to choose the enrollment of 20. Such planning illustrations do not represent observed power, and they cannot substitute for an outcome estimate or its uncertainty.

General explanation: over-dispersion occurs when variation in count data exceeds what a chosen statistical model expects. It can matter when counts are more variable than assumed, because standard errors and confidence intervals may then be too optimistic. The posted primary endpoint is described as a count parameter, but no count distribution, model, or analysis is reported. It is therefore not possible to determine whether over-dispersion was relevant or how it was handled.

Finally, the number of analyses is listed as zero. This means the registry record does not supply an inferential analysis to evaluate. It does not establish that no analyses were conducted outside the registry; that is not reported in the registry record. Without the analysis method, prespecified hypotheses, treatment of missing observations, and outcome results, statistical significance, precision, and robustness cannot be assessed from the posted results.

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("Main Group")
n      <- c(20)
events <- c(20)
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  Main Group  20  20  100.0  83.2  100.0  83.9  100.0  83.9  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and zero analyses. It does not report a statistical analysis plan, prespecified hypotheses, or a strategy for handling multiple statistical tests. Multiplicity arises in general when several outcomes, comparisons, time points, or analyses are examined, because the chance of at least one apparently notable result can increase as the number of tests grows. Whether multiplicity was relevant to the study’s actual analyses is not reported in the registry record.

The description includes both unipolar and bipolar electrograms, but the record does not state whether these were evaluated as separate predictors, combined into one measure, or compared using a defined statistical procedure. It also does not report thresholds, model selection, validation, or any adjustments for examining more than one predictor. These omissions prevent assessment of whether a reported predictive finding, if any, was prespecified or selected after examining the data.

Missing-data information is not reported in the registry record. There is no posted account of missing endpoint observations, reasons for missingness, exclusions, or methods for handling incomplete data. The enrollment of 20 does not by itself establish how many participants contributed to the primary outcome analysis. The registry also does not report an analysis population, such as whether all enrolled participants or a defined subset was used.

These details matter in general because missingness and analysis-population choices can affect an estimate and its precision. Without participant flow, an explicit denominator, and a description of missing-data handling, the completeness of the primary outcome cannot be judged. The absence of these details is not evidence that data were missing or that any particular method was used; those details are not reported in the registry record.

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 0% reporting threshold.

The registry’s adverse-event record lists 20 participants at risk for serious adverse events and zero participants affected. It also lists 20 at risk for other adverse events and zero affected, with zero deaths. These are counts recorded for the main group. The registry does not list serious adverse-event terms.

These figures should be read as the adverse-event counts posted in the registry, not as proof that no adverse events occurred outside the record’s definitions or observation period. The timeframe for adverse-event collection, event definitions, ascertainment procedures, and details of follow-up are not reported in the registry record. The counts therefore cannot be used to infer the duration or completeness of monitoring.

General explanation: when no events are observed in a limited group, the observation remains compatible with uncertainty about the underlying event frequency. A zero count does not establish that an event is impossible, and it does not by itself provide a precise estimate of risk. No uncertainty interval or further safety analysis is reported in the registry record.

The primary endpoint concerns termination of the clinical ventricular arrhythmia after RF energy delivery, whereas the adverse-event figures concern serious events, other events, and deaths. These are distinct outcome categories. The safety counts do not supply a result for the primary endpoint or demonstrate whether the electrogram measures predicted successful ablation targets.

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

The registry record establishes that a completed study enrolled 20 participants and set out to investigate whether unipolar and bipolar electrograms could help predict a successful ablation site for idiopathic outflow tract ventricular arrhythmia. It identifies RF ablation as the procedure and describes an intraoperative primary endpoint concerning termination of the clinical ventricular arrhythmia after energy delivery. These details describe the study’s question and registered outcome, not its findings.

The primary outcome value is not reported in the registry record. There is no posted event count, percentage, estimate of predictive performance, confidence interval, or statistical test. As a result, the posted results cannot show how often the endpoint occurred, how precisely it was estimated, or whether the electrogram measures differed in their ability to identify a target associated with termination.

The record also does not establish a randomized comparison. Allocation is not stated, and any arms are flagged as not being a like-for-like control comparison. The stated research aim should therefore not be translated into a claim that one approach was superior to another. The registry does not report a formal comparison or the methods needed to interpret one.

The endpoint description has an unresolved unit distinction: the title refers to a percentage of ablation targets, while the unit and parameter refer to a count of participants. Without an operational definition and denominator, even a reported count would need additional context to interpret its target-level meaning. That clarification is not reported in the registry record.

The adverse-event record lists zero serious adverse events, zero other adverse events, and zero deaths among 20 participants at risk. Those counts describe the posted safety data but do not establish absence of risk, particularly because the observation window and ascertainment details are not reported. Overall, the registry conveys the study’s objective and some design information, but the lack of posted primary analyses leaves the central predictive question unanswered in the record.

14. Why This Trial Matters Statistically

This study raises a statistical question that is broader than whether an event occurred after an ablation procedure: it asks whether electrogram information can predict which site will be associated with termination of the clinical ventricular arrhythmia. Predictive questions require a clearly defined predictor, outcome, observation unit, and method for evaluating performance. The registry states the general aim but does not report the measures needed to quantify prediction.

The distinction between targets and participants is especially important for the registered endpoint. A target-level question and a participant-level count can produce different denominators and different forms of uncertainty. If multiple targets were observed within a participant, those observations could be related. A sound analysis would need to account for the actual data structure. The registry does not say how targets and participants were linked or how the endpoint was operationalized.

The record also illustrates why design information constrains interpretation. It does not describe randomized allocation and explicitly notes that arms are not a like-for-like control comparison. Prediction, association, and causal comparison are different statistical aims. The study’s stated aim concerns prediction, but no posted analysis establishes predictive performance, and the design information does not support treating the record as a randomized treatment comparison.

Finally, an enrollment count and a completed status do not replace outcome reporting. Without a primary estimate and a measure of uncertainty, readers cannot distinguish a potentially informative result from one that is too imprecise to interpret. The registry’s zero-analysis listing and missing primary result make reporting completeness a central statistical issue, rather than a basis for conclusions about efficacy or predictive accuracy.

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 limitation for interpreting this trial is that the primary outcome result is not reported in the registry record. Although the record states the study objective and identifies a primary endpoint, it gives no observed count, percentage, predictive-performance estimate, confidence interval, or inferential test. The degree of uncertainty around the central result therefore cannot be evaluated.

The endpoint is not fully specified in the registry record. Its title refers to a percent of ablation targets, while its unit and parameter refer to participants and a count of participants. The description is empty. The record does not explain the denominator, target definition, event criteria, or whether participants could contribute multiple targets. These omissions limit interpretation of what an eventual endpoint count would represent.

Design information is also limited. Allocation is not stated, and the registry indicates that arms are not a like-for-like control comparison. The record does not describe a comparator, assignment method, or analysis comparing unipolar and bipolar electrograms. It also does not report participant characteristics, eligibility details, procedural methods, or a trial-specific sample-size justification. These details are not reported in the registry record.

The registry lists zero analyses and does not report an analysis population, missing-data handling, multiplicity strategy, or model specification. Thus, the completeness and analysis of the primary endpoint cannot be assessed. The adverse-event listing gives counts but no ascertainment window or event terms. Taken together, these limitations mean that the posted record supports a description of the study’s purpose and registered measures, but not a quantitative conclusion about predictive performance or a comprehensive assessment of uncertainty.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: EGM Analysis in Idiopathic Outflow Tract Ventricular Arrhythmia — NCT02722577.
• Registry record last updated 2019-08-06; status last verified 2019-07.
• Results first posted 2019-07-29.
• 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

NCT02722577 is a completed study of electrogram analysis in idiopathic outflow tract ventricular arrhythmia. The registry lists 20 participants, ventricular outflow tract tachycardia, and radio-frequency ablation. Its stated aim is to investigate the value of unipolar and bipolar electrograms for predicting a successful ablation site.

The primary endpoint concerns termination of the clinical ventricular arrhythmia after RF energy delivery, with an intraoperative timeframe described as an average of 2 hours. Its title refers to a percent of targets, while the listed unit and parameter refer to a count of participants; the registry does not explain this distinction. No primary outcome result or analysis is reported. Allocation is not stated, and the record does not describe a randomized, like-for-like comparison. The adverse-event listing records zero serious adverse events, zero other adverse events, and zero deaths among 20 at risk. Further endpoint, analysis, missing-data, and safety-monitoring details are not reported in the registry record.