ABLATOR Ablation Observational Registry: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for ABLATOR Ablation Observational Registry (NCT02344173), a registered phase not stated study. The primary outcome is Number of Subjects That Achieved Freedom From AF/AFL/AT (Atrial Fibrillation/Atrial Flutter/Atrial Tachycardia) With or Without the Use of Anti-arrhythmic Drugs After a 3-month Blanking Period..

2. Clinical Question

The endpoint allows anti-arrhythmic drug use and treats repeat ablation differently according to its timing: a repeat procedure during the blanking period does not count as an effectiveness failure, while one after that period does. Those rules define the outcome being counted, but they do not supply the count or establish how treatment compares with an alternative.

3. Trial Design

The ABLATOR Ablation Observational Registry is identified as an observational registry concerning atrial fibrillation. Its stated purpose was to assess the performance and clinical effectiveness of a combination of SJM mapping and ablation products. The sponsor was Abbott Medical Devices. Enrollment was 2035, and the registry status is COMPLETED.

The record gives a start of 2014-11 and a primary completion of 2017-08-18. It lists three outcome measures and 0 analyses. These entries describe what is recorded in the registry; they do not, by themselves, establish which statistical analyses were performed outside the registry record.

The primary outcome is a count of participants meeting a rhythm-status definition at 12 months post procedure. Its population is limited to subjects who completed the 12-month visit. The record does not report the number in that population, the number meeting the endpoint, or an estimate of the proportion meeting it.

A randomized allocation is not stated. The registry record does not identify a like-for-like control comparison, so treatment contrasts should not be read as randomized effects. The protocol, eligibility details, treatment assignment procedures, follow-up procedures beyond the endpoint description, and sample-size justification are not reported in the registry record. The posted sample-size assumptions describe an illustration rather than the registry’s own design.

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.

Enrollment

Procedure

Reasons for not completing this period:

12-month Visit

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Subjects that completed 12-month visit

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 Number of Subjects That Achieved Freedom From AF/AFL/AT (Atrial Fibrillation/Atrial Flutter/Atrial Tachycardia) With or Without the Use of Anti-arrhythmic Drugs After a 3-month Blanking Period., measured over 12 months post procedure.

The primary endpoint counts participants who achieved freedom from atrial fibrillation, atrial flutter, or atrial tachycardia, with or without anti-arrhythmic drugs, after a 3-month blanking period. The stated timeframe is 12 months post procedure, and the population is subjects who completed the 12-month visit. The endpoint is a count, not a continuous measurement such as a score or a change from baseline.

The definition specifies how repeat ablations affect classification. A repeat ablation during the blanking period does not count as an effectiveness failure. A repeat ablation after the blanking period does count as a failure. This timing rule is part of the endpoint definition and matters when interpreting what “freedom” means in this registry.

General statistical context: a binary endpoint reduces each participant’s outcome to whether the specified condition was met. Counts can be useful for communicating how many participants meet a clinically defined outcome, while a comparison or rate would be needed to place that count in context across groups or populations. The registry record does not report the number of participants achieving the endpoint, the denominator who completed the 12-month visit, or an endpoint estimate. Consequently, the stated definition can be described, but the frequency of success cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies the primary measure as a count of participants. It does not report an estimate for that endpoint, a confidence interval, or a hypothesis test. It also lists 0 analyses. As a result, there is no reported primary-outcome analysis from which to describe a treatment contrast or inferential result.

What does a count measure?

A count records how many participants meet a specified condition. In this registry, the condition is freedom from atrial fibrillation, atrial flutter, or atrial tachycardia, with or without anti-arrhythmic drugs, after the blanking period. The count depends on both the outcome definition and the group of participants assessed. The stated assessment population is subjects who completed the 12-month visit, but the size of that population and the count meeting the endpoint are not reported in the registry record.

General statistical context: a count alone is not the same as a rate or proportion. A proportion uses the number meeting the definition relative to a defined denominator. To interpret a proportion, the denominator and the outcome count must refer to a clearly specified population. An enrolled total does not automatically serve as the denominator when the endpoint is defined for a subset, as it is.

Why does the endpoint definition matter?

The endpoint specifies that anti-arrhythmic drugs may be used and that repeat ablations have different classifications depending on timing. A repeat ablation during the 3-month blanking period does not count as an effectiveness failure; a repeat ablation after that period does. Such rules determine how individual outcomes are categorized. The registry record does not report further operational details, such as how rhythm events were detected or adjudicated, so those procedures cannot be described.

General statistical context: an endpoint definition should be applied consistently across participants. Changes in measurement, follow-up, or classification can affect what a reported count represents. For that reason, the definition and the analysis population are both important when interpreting outcome results; the record gives the stated definition and population but not the result or the count of participants assessed.

What can a confidence interval tell a reader?

General statistical context: a confidence interval is an interval estimate that expresses sampling uncertainty around a statistical estimate under specified assumptions. Narrower intervals generally indicate more precision, while wider intervals indicate less precision. An interval does not remove possible bias from participant selection, missing follow-up, outcome measurement, or confounding. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be evaluated.

How should the planning illustration be read?

The stated sample-size assumptions describe a planning illustration computed from the observed effect, not the trial’s own design. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. The illustration is not evidence that the registry was randomized, used equal allocation, or was designed around those assumptions. The registry record does not report its own sample-size justification.

General statistical context: planning calculations ask how much information a future study might need to detect a chosen effect under specified assumptions. They do not measure the chance that the completed study’s result is correct, and they are not “observed power.” If the effect used as a planning reference comes from observed data, the planning result depends on that reference and on the assumptions. No numerical planning results are included in the registry information.

The stated assumptions refer to two arms, but the registry record does not identify a randomized two-arm comparison. The illustration should therefore be kept separate from the observed registry design. No arm-level outcomes, variance estimates, adjusted results, or inferential model are reported in the registry record. Without those details, readers cannot reconstruct a comparison or assess whether a particular model was appropriate.

Why can over-dispersion matter?

General statistical context: over-dispersion occurs when observed variability is greater than a model assumes. If a method assumes less variability than the data contain, standard errors can be too small and intervals too narrow. Appropriate methods depend on the outcome type, design, and data structure. The primary endpoint is a participant count, but the registry record does not report a fitted model, dispersion assessment, or statistical analysis for it. Over-dispersion should therefore be understood as a general methodological consideration, not as a reported feature of this registry.

More broadly, an observational registry can describe outcomes within its enrolled population, but a causal comparison requires design and analysis choices that address differences between groups. Allocation is not stated, and a like-for-like control comparison is not described. Any causal interpretation or adjustment strategy is not reported in the registry record.

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("Per-Protocol")
n      <- c(1932)
events <- c(1297)
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  Per-Protocol  1932  1297  67.1  65.0  69.2  65.0  69.2  65.0  69.2

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists three outcome measures and 0 analyses. It does not report a multiplicity strategy, such as a prespecified hierarchy, adjustment across outcomes, or a distinction between confirmatory and exploratory tests. The number of outcomes alone does not establish that multiple hypothesis tests were conducted. Because no analysis results are listed, the record does not support a conclusion about whether multiplicity affected any reported inference.

General statistical context: when several outcomes or repeated statistical tests are considered, the chance of at least one apparently unusual result can increase if each test is interpreted independently. A prespecified strategy can clarify which outcomes are primary and how tests should be interpreted. The registry identifies a primary outcome, but details of a broader statistical analysis plan are not reported in the registry record.

The primary endpoint is defined for subjects who completed the 12-month visit. The number who completed that visit, the number not assessed, and the handling of missing endpoint data are not reported in the registry record. No imputation method, sensitivity analysis, or missing-data assumption is described.

General statistical context: missing follow-up can affect an estimate when the likelihood of being observed is related to outcome status or other participant characteristics. Complete-case results describe those with observed outcomes; they need not represent all enrolled participants. Methods for addressing missingness rely on assumptions and should be reported alongside the analysis population. Since the relevant counts and methods are absent, the extent and possible impact of missing primary-outcome data cannot be evaluated.

The analysis populations, including whether any participants were excluded from the primary outcome assessment, are not reported in the registry record. The entry listing 0 analyses does not establish which participants were included in any analysis outside 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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: arrhythmia (12.2%), other (1.5%), exacerbation of pre-existing atrial fibrillation (1.0%), pericardial effusion/cardiac tamponade (0.7%), angina (chest pain) (0.5%).

For all enrolled subjects, the registry lists 2035 at risk for serious adverse events and 356 affected. It also lists 8 deaths. The record lists 0 subjects at risk for other adverse events and 0 affected; those entries do not provide a basis for interpreting other adverse events in a broader population.

The most frequently listed serious adverse event terms are Arrhythmia at 12.2%, Other at 1.5%, Exacerbation of Pre-Existing Atrial Fibrillation at 1.0%, Pericardial Effusion/Cardiac Tamponade at 0.7%, Angina (Chest Pain) at 0.5%, and Vascular Access/Bleeding Complications at 0.4%. The registry record does not report the denominator used for these term percentages or further details about event classification.

General statistical context: a serious adverse event count describes reported events or affected participants according to the registry’s reporting conventions; it does not, on its own, establish that a procedure or product caused an event. The listed terms and figures should be read as registry safety reporting, not as a comparison between treatments. A comparator and a causal analysis are not described in the registry record. The timing, relatedness assessments, and method used to select these terms are not reported in the registry record.

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

The registry record establishes that an observational registry enrolled 2035 subjects with atrial fibrillation and that its primary outcome was defined around freedom from atrial fibrillation, atrial flutter, or atrial tachycardia at 12 months post procedure. It also reports serious adverse event information for all enrolled subjects, including 356 affected and 8 deaths, and lists several serious adverse event terms with percentages.

It does not report how many subjects completed the 12-month visit or how many met the primary endpoint. Accordingly, the primary outcome cannot be quantified from the record, and its precision cannot be evaluated. No confidence interval or primary-outcome test result is reported. The serious adverse event figures do not fill that gap: they describe a different set of outcomes and do not establish the primary endpoint result.

General statistical context: a registry outcome can describe what was recorded for participants under the registry’s definitions. Establishing whether an intervention caused a difference requires an appropriate comparison and careful consideration of confounding, outcome measurement, and missing data. Here, randomization is not described, allocation is not stated, and a like-for-like control comparison is not identified. The record therefore does not support a randomized treatment-effect interpretation.

The endpoint permits anti-arrhythmic drug use and defines repeat ablation during the blanking period differently from repeat ablation afterward. These details help explain what the registry intended to count, but they do not show the frequency of that outcome. Protocol details, analysis populations, missing-data methods, and the registry’s own sample-size justification are not reported in the registry record.

The posted sample-size assumptions are a planning illustration based on an observed effect and stated hypothetical design assumptions. They are not an observed outcome, a result of a randomized comparison, or evidence of the registry’s planned sample size. The record’s listing of 0 analyses also means no analysis results are available to interpret from that entry. The most defensible reading is limited to the registry’s stated purpose, endpoint definition, enrollment, status, and reported safety figures.

14. Why This Trial Matters Statistically

Statistically, this registry illustrates the difference between defining an outcome and reporting an outcome result. The primary endpoint is described in detail: it is a participant count, assessed at 12 months post procedure among subjects who completed that visit, with explicit rules for anti-arrhythmic drug use and repeat ablation timing. Yet the endpoint count and the size of the assessment population are not reported in the registry record. Without those quantities, the endpoint cannot be summarized as a frequency or evaluated for precision.

The observational design also matters for interpretation. Allocation is not stated and a like-for-like control comparison is not described. General statistical context: an observed outcome after treatment is not, by itself, an estimate of what would have happened under an alternative treatment or no treatment. Comparisons intended to answer causal questions require a suitable design and analysis, and the relevant details are not reported in the registry record.

The registry record separately reports serious adverse event information, including 356 affected subjects among 2035 at risk and 8 deaths. Those figures provide descriptive safety information as recorded, while the associated term percentages provide additional reported categories. The record does not state the denominator for those percentages or provide a comparative safety analysis.

Finally, the planning illustration should be distinguished from the study’s actual design and results. Its assumptions describe a hypothetical planning calculation, not a randomized comparison or observed power. This distinction is useful when reading registry records: methodological assumptions, outcome definitions, and outcome findings answer different questions. In this case, the definition and some safety counts are available, but the primary endpoint result and detailed analysis methods are not reported.

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.

Several trial-specific details needed to assess the primary outcome are not reported in the registry record. The number of subjects completing the 12-month visit and the number achieving freedom from atrial fibrillation, atrial flutter, or atrial tachycardia are absent. No estimate, confidence interval, p-value, or other primary-outcome analysis result is reported. The record therefore does not permit an assessment of endpoint frequency or precision.

The registry is observational, allocation is not stated, and a like-for-like control comparison is not described. This limits what can be inferred about comparative effects. The registry record does not report adjustment methods or other approaches to address differences between groups. The protocol, eligibility criteria, detailed treatment procedures, and outcome ascertainment procedures are also not reported in the registry record.

The primary endpoint population is defined as subjects completing the 12-month visit, but the number completing that visit and the handling of missing outcomes are not reported. Analysis-population definitions and exclusions are not reported either. As a result, the relationship between enrollment and the population contributing to the primary outcome cannot be evaluated.

The record lists three outcome measures and 0 analyses, but does not report a multiplicity plan or a full statistical analysis plan. The registry’s own sample-size justification is not reported; the stated planning assumptions are an illustration and do not establish the study’s design rationale. For safety, the record reports serious adverse event counts and term percentages, but the denominator for the term percentages, event relatedness, and comparative safety results are not reported.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: ABLATOR Ablation Observational Registry — NCT02344173.
• Registry record last updated 2019-06-05; status last verified 2019-02.
• Results first posted 2019-06-05.
• 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 ABLATOR Ablation Observational Registry concerns atrial fibrillation and was sponsored by Abbott Medical Devices. It enrolled 2035 subjects and is listed as COMPLETED. The registry record gives a start of 2014-11 and a primary completion of 2017-08-18.

Its stated purpose was to assess the performance and clinical effectiveness of a combination of SJM mapping and ablation products. The primary endpoint counts subjects who achieved freedom from atrial fibrillation, atrial flutter, or atrial tachycardia, with or without anti-arrhythmic drugs, at 12 months post procedure, following a 3-month blanking period. The endpoint result and the number completing the 12-month visit are not reported in the registry record.

The record lists three outcome measures and 0 analyses. For all enrolled subjects, it reports 356 affected by serious adverse events and 8 deaths. It does not describe a randomized comparison, and allocation is not stated.