Advisor HD Grid Observational Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Advisor HD Grid Observational Study (NCT03733392), a registered phase not stated study. The primary outcome is Rate of Subjects With Acute Success.

2. Clinical Question

The study concerns the use of the Advisor HD Grid Mapping Catheter, Sensor Enabled, alongside electroanatomical mapping and radiofrequency (RF) energy delivery in real-world clinical settings. The registry describes participants with persistent atrial fibrillation (PersAF) or ventricular tachycardia (VT) who underwent ablation. Its primary question is whether the clinical arrhythmia was acutely terminated or could no longer be induced after the procedure, according to the endpoint definition.

The endpoint definition allows termination to sinus rhythm, or to atrial tachycardia when treating PersAF. It also allows cardioversion before the inducibility attempt. The registry lists overall procedure time, RF time, fluoroscopy time, mapping time, mapping-point measures, substrate characteristics, and map type among secondary outcomes. However, the primary-outcome result is not reported in the registry record. The record therefore establishes the question being asked, but does not permit a numerical answer about acute success.

3. Trial Design

The Advisor High Density (HD) Grid Mapping Catheter Observational Study is listed as completed. The registry lists enrollment of 379 and gives a start date of 2019-01-11 and a primary completion date of 2021-05-27. Abbott Medical Devices is named as the sponsor. The conditions are persistent atrial fibrillation and ventricular tachycardia, and the listed intervention is the Advisor HD Grid Mapping Catheter, Sensor Enabled.

The study aim is to quantify and characterize outcomes of RF ablation after, and the utility of electroanatomical mapping with, the HD Grid catheter and the EnSite Precision Cardiac Mapping System with HD Wave Solution voltage mapping. The aim specifies real-world clinical settings. This is an observational study, not a randomized comparison; allocation is not stated in the registry record. The two clinical groups are not a like-for-like control comparison, so differences between them cannot be interpreted as treatment effects of one group versus the other.

The primary outcome is the rate of subjects with acute success, assessed immediately after the procedure. The registry defines eligible primary-outcome populations separately for PersAF and VT: participants indicated for ablation who had the HD Grid catheter inserted and RF energy applied according to label. The record also lists secondary outcomes covering procedure and mapping measures, mapping points, identified substrate characteristics, and the map type used to define the ablation strategy. It lists 22 outcome measures overall, but no numerical primary-outcome result or statistical analysis is reported in the registry record.

The registry record does not report the protocol's sample-size justification, a statistical analysis plan, interim analyses, or a detailed allocation procedure. It also does not describe a comparator intervention. These omissions limit what can be inferred about how the study was planned and how its outcomes were intended to be analyzed.

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: 372 of the 379 enrolled subjects started and completed the ablation procedure. The remaining 7 subjects (5 PersAF, 2 VT) were withdrawn prior to procedure due to presence of thrombus, mapping system incompatible with the HD Grid, subject withdrawal of consent, and/or early enrollment closure.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: PersAF: Subjects indicated for ablation to treat PersAF in which the HD grid catheter was inserted, and RF energy was applied according to label. VT: Subjects indicated for ablation to treat VT in which the HD grid catheter was inserted, and RF energy was applied according to label.

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 Subjects With Acute Success, measured over Immediate post procedure.

The primary endpoint is the rate of participants with acute success, measured immediately after the procedure. It is defined as the percentage of participants who received HD Grid mapping and RF energy delivery according to label and then had acute termination of the clinical arrhythmia or non-inducibility of that arrhythmia after ablation. Termination to sinus rhythm qualifies; for PersAF treatment, termination to atrial tachycardia also qualifies. Cardioversion is allowed before the inducibility attempt.

This endpoint is used to describe an immediate procedural outcome rather than a later clinical course. It gives a defined way to classify whether the arrhythmia was terminated or could not be induced at the end of the ablation procedure. The separate population definitions matter: the endpoint applies to participants indicated for ablation whose catheter was inserted and who received RF energy according to label. It does not automatically describe all participants included in the registry's enrollment figure.

The definition states what counts as success, but the registry record does not report the number meeting that definition, the denominator analyzed, or an uncertainty interval for the primary outcome. Without those results, the endpoint cannot be quantified from the registry record. Acute procedural status also should not be conflated with later recurrence or longer-term health outcomes, which are not part of this primary endpoint definition.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a binary endpoint represent?

The primary endpoint is binary at the participant level: a participant either meets the acute-success definition or does not. The registry describes the outcome as a rate, expressed as a percentage. To interpret such a result, readers need both the number meeting the definition and the denominator included in the analysis. The registry record does not report either primary-outcome count or its analyzed denominator, so the rate cannot be reconstructed.

A confidence interval is a statistical range used to convey uncertainty around an estimated outcome. In general, a wider interval indicates less precision, while a narrower interval indicates greater precision, under the assumptions of the method used. No primary-outcome confidence interval is reported in the registry record. It is therefore not possible to assess the statistical precision of acute success from this record, even if the endpoint definition itself is clear.

Why does the observational design matter?

In a randomized study, allocation is designed to create comparable groups on average, making a treatment contrast more interpretable. In an observational study, treatment or exposure allocation is not assigned by randomization. Differences in participants, clinical circumstances, or other care can influence observed outcomes. The record does not state an allocation method and does not describe a like-for-like control comparison. Consequently, a descriptive outcome in this study would characterize the recorded clinical experience, but it would not by itself identify a causal effect of the device or mapping strategy.

The PersAF and VT groups address different conditions and are not interchangeable control groups. Comparing their outcomes directly would mix differences in underlying clinical setting with any differences in procedure or mapping. The record does not report an analysis that adjusts for such differences. It is therefore important to read each group as a distinct descriptive population, not as a randomized arm.

What can be concluded from a count?

A count records how many events or participants were observed, while a denominator establishes the population in which that count arose. For the reported safety groups, the record gives denominators and event counts. Those figures are useful descriptions, but they do not automatically provide a comparison with another treatment or setting. Interpretation also depends on how events were defined, observed, and attributed; those details are not fully reported in the registry record.

For the primary endpoint, no outcome count or denominator is reported. It is not appropriate to infer a rate from the safety counts or from the overall enrollment figure, because those refer to different information and may represent different analysis populations. No recalculated primary estimate is available from the reported information.

How should statistical significance be understood?

A statistical test evaluates how compatible observed data are with a specified statistical model or null hypothesis. A p-value, when reported, does not measure the size or clinical importance of an effect, and it does not establish causation. The registry record reports no primary-outcome test, p-value, or inferential analysis. No conclusion about statistical significance can therefore be drawn from the record.

Even when an estimate and test are available, interpretation should consider the magnitude of the estimate, its uncertainty, the study design, and how outcomes were selected. In this study, the missing primary result and absence of a reported analysis prevent those evaluations. General statistical principles cannot substitute for the absent study-specific result.

What does the outcome list imply for analysis?

The registry lists 22 outcome measures, with primary and secondary outcomes covering different procedural and mapping characteristics. When a study evaluates multiple outcomes, the chance of finding at least one apparently notable result can increase if each is tested separately without an appropriate plan. Statistical methods can address this issue, but the method should be prespecified and interpreted in relation to the study aims. The record does not report a multiplicity strategy, nor does it report analyses of the listed outcomes.

The registry's study design and outcome definitions provide context for what would be measured, but they do not disclose the statistical plan. The sample-size justification, handling of missing data, interim analyses, and model specifications are not reported in the registry record. Without those details and the outcome results, readers cannot evaluate whether planned analyses were followed, whether assumptions were checked, or how robust any estimate might be.

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("PersAF Subjects", "VT Subjects")
n      <- c(334, 16)
events <- c(287, 14)
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  PersAF Subjects  334  287  85.9  81.7  89.5  81.8  89.3  81.8  89.2
ARM  VT Subjects  16  14  87.5  61.7  98.4  64.0  96.5  63.6  96.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 22 outcome measures, including the primary acute-success endpoint and secondary measures involving procedure time, RF time, fluoroscopy time, mapping time, mapping-point collection, substrate characteristics, and map type. Assessing many outcomes can raise multiplicity concerns: if each outcome is tested independently, the overall chance of at least one apparently significant finding may be higher than for a single prespecified test. This is a general statistical issue, not evidence that the study's findings were affected in a particular way.

The registry record does not report a multiplicity adjustment, an outcome hierarchy beyond identifying the primary endpoint, or analyses for the listed outcomes. It also does not report a statistical analysis plan. It is therefore not possible to determine whether outcomes were prespecified in detail, how multiple comparisons were to be interpreted, or whether any adjustment was planned.

Missing-data methods and analysis populations are also not reported in the registry record. Although the primary endpoint specifies eligible participants as those indicated for ablation who had the catheter inserted and RF energy applied according to label, the record does not state the number meeting those criteria, the number analyzed, or how participants with incomplete outcome information were handled. No participant flow or missingness summary is reported. The record also does not state whether interim analyses were planned or conducted, or provide the protocol's sample-size justification.

These gaps do not establish that missing data or multiplicity affected results; rather, they prevent readers from evaluating those issues. General statistical guidance cannot identify the methods used in this study when the registry record does not report them.

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

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cardiac perforation or tamponade (10.5%), pericardial effusion (5.3%), transient ischemic attack (tia) (5.3%), arrhythmia new (3.0%), arrhythmia pre-existing (2.6%).

For PersAF Subjects, the registry reports 334 at risk for serious adverse events, 39 affected by serious adverse events, 334 at risk for other adverse events, 10 affected by other adverse events, and 1 death. For VT Subjects, it reports 38 at risk for serious adverse events, 11 affected by serious adverse events, 38 at risk for other adverse events, 0 affected by other adverse events, and 0 deaths. These are descriptive counts as recorded for the two groups.

The listed serious-event terms and percentages are cardiac perforation or tamponade, 10.5%; pericardial effusion, 5.3%; transient ischemic attack (TIA), 5.3%; new arrhythmia, 3.0%; pre-existing arrhythmia, 2.6%; and infection, 2.6%. The registry record does not clarify the denominator or method underlying these term percentages, so they should not be treated as group-specific rates without further information.

Event counts do not establish causation. The record does not provide enough detail to determine the timing, severity grading, relatedness assessment, or participant-level overlap among event terms. Nor does it provide a comparable control group for estimating relative safety. The figures describe events recorded in the listed groups; they do not, by themselves, show whether the device or procedure caused them.

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

The record establishes that the study was designed to describe outcomes associated with HD Grid mapping and RF ablation in real-world settings among participants with PersAF or VT. It gives a specific definition of acute success and reports selected safety counts. Those features make the clinical question and some aspects of the safety experience identifiable.

However, the primary acute-success result is not reported in the registry record. There is no reported number of participants meeting the endpoint, analyzed denominator, percentage, confidence interval, or inferential analysis. Thus, the registry record does not quantify acute success or its precision. The completed status of the study does not fill in these missing results.

The observational design also means that the study should not be interpreted as a randomized test of the device against a control. Allocation is not stated, and no like-for-like control comparison is described. Even if outcome rates were available, a descriptive finding would not alone establish that the mapping catheter or mapping approach caused the outcome. The record does not report statistical adjustments that might address differences among participants or clinical settings.

Similarly, the reported safety counts are not comparative causal estimates. They provide event counts for the PersAF and VT groups, but not a controlled estimate of excess risk or attribution to the device or procedure. The serious-event term percentages lack a stated denominator in the registry record.

The appropriate interpretation is therefore limited: the registry describes a completed observational study, its intended acute endpoint, several secondary outcomes, and selected adverse-event counts. It does not report the primary result or analyses needed to assess precision, statistical significance, multiplicity, or causal effects. No conclusion about whether a treatment works or does not work follows from the information recorded.

14. Why This Trial Matters Statistically

This study illustrates the distinction between a clearly defined endpoint and a reported result. The acute-success definition specifies the clinical event and the time of assessment, including how termination and non-inducibility count. That clarity helps readers understand what the investigators intended to measure. But without the endpoint count, denominator, and estimate, the question remains unquantified in the registry record.

It also illustrates why design labels matter. An observational study can describe outcomes in actual clinical settings, which may be useful for characterizing procedures and mapping practice. At the same time, absent random allocation and a suitable control comparison, descriptive outcomes cannot isolate the effect of a device or mapping approach from other influences. Recognizing that distinction avoids treating groups with different arrhythmias as treatment arms.

The record names a broad range of secondary outcomes, from procedure and imaging times to mapping-point measures and substrate descriptions. Such breadth raises practical questions about prespecification, analytic priorities, and multiplicity. The registry record does not report an analysis plan or results for those outcomes, so those questions cannot be resolved from the available information.

Finally, safety counts need denominators and context. The record provides group denominators and counts for serious and other adverse events, as well as deaths, but does not explain event attribution or the denominator underlying serious-event term percentages. Reading those figures as descriptive rather than causal is essential. Together, these features show why statistical interpretation depends not only on endpoint definitions and event counts, but also on complete reporting of populations, analyses, uncertainty, and design.

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 limitations follow from what the registry record does and does not report. Most importantly, it does not report the primary acute-success outcome count, analyzed denominator, percentage, confidence interval, or statistical test. The study's principal endpoint therefore cannot be quantified or assessed for precision.

The study is observational, allocation is not stated, and the record identifies no like-for-like control comparison. The PersAF and VT groups represent distinct clinical populations, not randomized arms. The registry record does not describe statistical adjustment for differences among participants or clinical settings, so causal interpretation is not supported by the recorded design information.

The record lists enrollment of 379 but does not provide a participant flow that connects this figure to the populations used for the primary endpoint or safety outcomes. It does not report the number eligible for the primary endpoint, exclusions, outcome availability, or handling of missing observations. The number enrolled should not be assumed to be the denominator for every outcome.

The registry lists 22 outcome measures but reports no analyses. It does not state how multiplicity was addressed, how secondary outcomes were analyzed, or whether any interim analyses occurred. The sample-size justification and detailed statistical analysis plan are not reported in the registry record. The serious-event term percentages are presented without a stated denominator or detail on event attribution, timing, or overlap. These reporting gaps restrict interpretation of both effectiveness and safety, without establishing that any particular bias or analysis problem occurred.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Advisor HD Grid Observational Study — NCT03733392.
• Registry record last updated 2024-04-16; status last verified 2024-04.
• Results first posted 2024-04-16.
• 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

NCT03733392 is the completed Advisor High Density (HD) Grid Mapping Catheter Observational Study, sponsored by Abbott Medical Devices. The registry lists enrollment of 379, with a start date of 2019-01-11 and primary completion date of 2021-05-27. The study concerns participants with persistent atrial fibrillation or ventricular tachycardia and lists the Advisor HD Grid Mapping Catheter, Sensor Enabled, as the intervention.

The primary endpoint is acute success immediately after the procedure, defined using acute arrhythmia termination or non-inducibility after ablation. The registry also lists 22 outcome measures and reports selected serious-event, other-event, and death counts for PersAF and VT groups. The primary outcome result and statistical analyses are not reported in the registry record. Allocation is not stated, and the record does not describe a like-for-like control comparison.