This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Evaluating Active Esophageal Cooling During Cardiac Ablation Procedures (NCT04063761), a na na study. The primary outcome is Total Time of Active Ablation Procedure.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04063761 |
| Phase | NA |
| Condition | Atrial Fibrillation |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Advanced Cooling Therapy, Inc., d/b/a Attune Medical |
| Results posted | Yes |
2. Clinical Question
Population
People with atrial fibrillation undergoing left atrial radiofrequency ablation are the clinical population of interest. The registry record does not report detailed eligibility criteria or a fuller description of the enrolled participants.
Intervention
Participants in the study arm received the Attune Medical Esophageal Heat Transfer Device for active esophageal cooling during left atrial ablation. The study addresses cooling in the setting of radiofrequency energy delivery.
Comparator
There is no control group in this single-group study. The registry lists no randomized or concurrent comparison, so the study does not directly compare cooling with usual care or another cooling approach.
Primary question
The primary endpoint asks about the total time of the active ablation procedure, measured in hours during left atrial radiofrequency ablation. The stated purpose is to evaluate procedural efficiency when esophageal heat transfer is used to cool the esophagus.
The registry background describes esophageal injury as a potential consequence of left atrial radiofrequency ablation. It notes that esophageal mucosal lesions may be detected after pulmonary vein isolation and that active cooling has been investigated in mathematical models, pre-clinical studies, and clinical trials. Those background statements motivate the study; they are not results from this study.
Two secondary outcomes are listed: total procedure time and the number of procedural pauses during left atrial instrumentation. Together, the listed outcomes address aspects of procedural duration and workflow. The registry does not report numerical results for the primary or secondary outcomes, so the record does not establish what procedure times or pause counts were observed.
3. Trial Design
This is a completed, single-group device study with an enrollment of 20. The listed arm is Esophageal Cooling, in which patients received the Attune Medical Esophageal Heat Transfer Device. The registry identifies the condition as atrial fibrillation and the device as the intervention.
The allocation field is listed as NA, masking is listed as NONE, and the study model is SINGLE GROUP. There is no like-for-like control arm in the registry record. Accordingly, the design can describe outcomes among participants receiving the cooling device, but it does not provide a concurrent comparison from which to isolate the device’s effect relative to no cooling or another approach.
The registry lists the study start as 2019-06-20, primary completion as 2021-02-01, and status as COMPLETED. The phase is listed as NA. These registry fields describe the study record; they do not supply a detailed account of recruitment, follow-up, or the timing of each participant’s procedures.
The primary outcome is total time of active ablation procedure, measured in hours. Its timeframe is Study Day 1 for all patients enrolled, during left atrial ablation procedures using radiofrequency energy, up to 5 hours. The registry says total procedure time was documented by a clinician recorder and research coordinator. Secondary outcomes are total procedure time and the number of procedural pauses during left atrial instrumentation.
Although the record says the study was completed, it does not report the protocol’s eligibility criteria, the rationale for its enrollment target, or detailed procedures for outcome collection. It lists no analysis records. The registry record therefore supports a description of the planned measures and design, but not a detailed reconstruction of how analyses were conducted or how complete outcome data were.
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.
Overall Study
| Stage | Esophageal Cooling |
|---|---|
| STARTED | 20 |
| COMPLETED | 20 |
| NOT COMPLETED | 0 |
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.
| Characteristic | Unit | Esophageal Cooling |
|---|---|---|
| Participants analysed | 20 | |
| Age, Continuous | years | 66 (SD 11) |
| Sex: Female, Male: Female | Participants | 8 |
| Sex: Female, Male: Male | Participants | 12 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 20 |
6. Primary Endpoint
The registry lists the primary outcome as Total Time of Active Ablation Procedure, measured over Study Day 1 for all patients enrolled, during left atrial ablation procedures using radiofrequency energy, up to 5 hours.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Hours |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled Total Time of Active Ablation Procedure. It is a continuous measure expressed in hours, with the mean specified as the summary measure and the standard deviation as its dispersion measure. The timeframe is Study Day 1 during left atrial radiofrequency ablation, up to 5 hours. Measurement is described as total procedure time documented by a clinician recorder and research coordinator.
Procedure time is used to address the stated purpose of evaluating procedural efficiency when active esophageal cooling is used during left atrial ablation. Time is a direct operational measure: it describes duration, rather than a clinical event or a measure of esophageal injury. It can therefore speak to the procedural-efficiency question, but it cannot by itself describe tissue injury, rhythm outcomes, or other benefits and harms.
The registry also lists total procedure time as a secondary outcome. It does not explain how that secondary measure differs from the primary active ablation time, including which start and stop points define either measure. The meaning of any difference between these labels is therefore not reported in the registry record. Numerical observations, a mean, a standard deviation, and an estimate of precision for the primary endpoint are also not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The design and outcome definitions are clear enough to identify the question the study set out to address: whether using active esophageal cooling during left atrial radiofrequency ablation is associated with procedural time and workflow measures in this single group. The registry lists total active ablation procedure time as the primary outcome and procedural pauses and total procedure time as secondary outcomes. It does not, however, provide numerical results for these measures.
Consequently, no conclusion about the observed duration of ablation, the average procedure time, or the number of pauses can be drawn from the registry record. A mean and standard deviation are specified as the intended summary for the primary continuous endpoint, but the values themselves are not reported in the registry record. There is also no confidence interval or other reported estimate of uncertainty for the primary outcome, and no analysis records are listed.
The single-group design is important to interpretation. Even if outcome values were available, a description of time among participants who received cooling would not, by itself, show what their procedure times would have been without cooling. Procedure duration can reflect many features of the procedure and the people performing it; the registry record does not report a control group or a method that would provide a direct counterfactual comparison. Thus, a within-group description should not be interpreted as a comparative treatment effect.
The enrollment of 20 describes the registered study enrollment. It does not establish that primary endpoint data were available for every participant, because completeness of endpoint observations is not reported in the registry record. Nor does enrollment alone establish how precisely a mean would be estimated; precision depends on observed variability and the amount of usable data, neither of which is reported for the primary endpoint.
The registry’s adverse-event figures list no serious adverse events, no other adverse events, and no deaths in the Esophageal Cooling group, with 20 at risk for each of the two adverse-event categories. These are reported counts for this study record, not a comparative safety estimate. The record does not provide detail about event-collection methods, follow-up completeness, or the ability of this study to detect uncommon events.
The registry background discusses potential esophageal injury from ablation and the rationale for cooling. Such background context is not evidence that an injury outcome was measured or prevented in this particular study. The posted record does not report an esophageal-injury endpoint result. The most defensible reading is therefore limited: the study was designed to examine procedure time and pauses while using cooling, but numerical efficacy and endpoint results are not reported in the registry record.
9. Statistical Methods Explained
What does the primary summary measure?
The primary outcome is continuous, and the registry specifies the mean and standard deviation. The mean describes the arithmetic average of the recorded procedure times. The standard deviation describes how spread out individual recorded times are around that average. These summaries answer different questions: the mean gives a central value, while the standard deviation characterizes variation among observations.
Neither summary is reported for this endpoint in the registry record. A reader therefore cannot determine the average time, the observed spread, or whether unusually long or short procedures influenced the mean. A mean and standard deviation also do not show the full shape of the data. In general, a distribution can be skewed or contain influential observations; whether that applies to these procedure times is not reported in the registry record.
What would a confidence interval add?
In general, a confidence interval gives a range of values compatible with the data and the method used to estimate the quantity. Its width communicates precision: a narrower interval indicates greater precision under the analysis assumptions, while a wider interval indicates more uncertainty. A confidence interval is not a guarantee that the true value lies within its limits, and it does not correct bias from a design or measurement problem.
No confidence interval for the primary outcome is reported in the registry record. Because neither the endpoint summary nor its uncertainty is available, the precision of an estimated average procedure time cannot be assessed. The absence of a reported interval should not be treated as evidence that the estimate is precise or imprecise.
Why does the single-group design matter?
A single-group study can describe measurements in the participants receiving an intervention. It lacks a concurrent group to show what would have happened under a different approach. In general, comparing a group’s observed outcome with a hypothetical or historical value may be affected by differences in participants, clinical practice, measurement, and other factors. The registry record does not report a control group or a comparative analysis for procedure time.
For this study, an observed mean time, if reported, would describe the cooling group. It would not alone quantify a difference attributable to cooling. The registry’s listed allocation is NA and its model is SINGLE GROUP; these design features should remain central to interpretation rather than treating the study as a randomized comparison.
How should planning illustrations be read?
The registry describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect, and that non-time-to-event planning values are expressed as participants per arm. These are assumptions for an illustrative planning calculation, not a description of this study’s design: the actual record is single-group, with no two-arm allocation listed.
Such planning values are not observed power. In general, a sample-size calculation describes the sample size associated with specified assumptions about an effect, variability, and testing procedure. It does not show the probability that a completed study has established a result, and it cannot replace a confidence interval or an outcome analysis. The registry states that the illustration is computed from the observed effect, but the primary endpoint’s observed effect is not reported in the registry record. The illustration’s numerical values and the underlying observed endpoint summaries are not reported in the registry record.
What can be said about the analysis plan?
The primary endpoint’s type and intended descriptive summaries are listed, but the registry lists no analysis records. It does not report a statistical model, an inferential test, a confidence-interval procedure, or a prespecified approach to unusual observations. It also does not report whether any adjustment or subgroup analysis was planned. These details should not be inferred from the endpoint definition or from the planning illustration.
In general, choosing an analysis involves matching the method to the outcome, design, and scientific question. For continuous time measurements, analysts may describe the distribution and estimate a mean or other summary, but the appropriate inferential method depends on the actual data and assumptions. Since no numerical endpoint results or analysis details are reported, no particular distributional assumption or inferential conclusion can be attributed to this study.
10. Confidence Intervals for Each Arm
No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Esophageal Cooling | 20 | 3.260 | 0.700 | 2.932 to 3.588 |
R code and output
arm <- c("Esophageal Cooling")
n <- c(20)
m <- c(3.26)
sp <- c(0.7)
sd <- sp # posted standard deviations
for (i in seq_along(n)) {
se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}
CARM Esophageal Cooling 20 3.260 0.700 2.932 3.58811. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and two secondary outcomes: total procedure time and the number of procedural pauses during left atrial instrumentation. It does not report a multiplicity strategy, such as whether secondary outcomes were treated as exploratory or whether any adjustment for multiple statistical tests was planned. The registry lists no analysis records, so it is not possible to determine whether inferential tests were performed or how multiple outcomes were handled.
In general, evaluating several outcomes can increase the chance of a chance finding when each is tested separately. A prespecified testing hierarchy or another multiplicity approach can clarify how results should be interpreted. Without a reported strategy, no claim about family-wise error control or confirmatory status should be made for the listed outcomes.
Missing-data methods and endpoint completeness are not reported in the registry record. The registered enrollment does not establish how many participants contributed primary or secondary outcome data. The record does not describe exclusions, withdrawals, imputation, or sensitivity analyses for missing observations. It also does not specify an analysis population, such as whether results were to include all enrolled participants or only those with evaluable procedures.
In general, missingness can affect both the number of observations available and the interpretation of an estimate, particularly when the reasons for missing data relate to the outcome. Without a reported accounting of available data and the handling of missing values, readers cannot assess the potential impact on the endpoint summaries. These are reporting gaps, not evidence that data were missing or that any particular method was used.
12. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Esophageal Cooling | 0 | 20 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Esophageal Cooling | 0 of 20 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Esophageal Cooling | 0 of 20 |
The registry lists 0 serious adverse events among 20 at risk in the Esophageal Cooling group. It lists 0 other adverse events among 20 at risk, and 0 deaths. No serious adverse-event terms are listed. These figures describe the counts recorded in the registry; they do not provide a comparison with another group.
A zero count does not establish that an event is impossible or that risk is absent. In general, observed event counts depend on the number of people followed, the length and completeness of follow-up, and how events are defined and collected. The registry record does not report detailed event-collection procedures, follow-up duration for safety, or an assessment of how well the study could detect uncommon events.
The two at-risk figures are category-specific registry entries. They should be read as the denominators attached to the serious and other adverse-event counts, not as a basis for inferring broader safety outcomes. The listed counts do not establish the absence of all possible harms, and they do not answer whether cooling changes risk relative to another approach. No such comparator is listed.
13. What the Result Does, and Does Not, Mean
The record establishes that a completed single-group study enrolled 20 participants and used an esophageal heat transfer device during left atrial radiofrequency ablation. It identifies procedure duration as the primary question of interest and lists total procedure time and procedural pauses as secondary measures. The record also lists zero serious adverse events, zero other adverse events, and zero deaths in the cooling group.
It does not report numerical values for the primary or secondary procedural outcomes. There is no primary endpoint mean or standard deviation, and no estimate of uncertainty is reported. As a result, readers cannot judge the observed duration, the variation in duration, or how precisely the mean was estimated from the registry record.
The single-group design also limits what the study can show. Without a control group, the record cannot provide a direct estimate of how procedure time or pauses compare with procedures conducted without the device or with a different approach. Background statements about potential esophageal injury and the rationale for cooling do not substitute for reported results on injury prevention. Such an endpoint result is not reported in the registry record.
The adverse-event counts are descriptive and should be interpreted within the study’s reported follow-up and ascertainment limits, which are not detailed in the registry record. They are not a comparative safety analysis and do not establish that rare events cannot occur. Overall, the registry defines a procedural-efficiency question and records a small single-group experience, but it does not report the numerical outcome results needed to assess the magnitude or precision of procedural findings.
14. Why This Trial Matters Statistically
This study is statistically instructive because its primary question concerns a continuous procedural measure, while its design is a single group. A mean and standard deviation can describe procedure time among participants receiving cooling, but a treatment comparison requires more than a within-group description. Without a concurrent comparator, the registry cannot separate any observed time pattern from other influences on procedure duration.
The distinction between the question and the available evidence matters. The stated purpose is to evaluate procedural efficiency, and the primary endpoint is total time of active ablation procedure. The registry does not report its numerical result. Thus the study’s endpoint definition should not be mistaken for evidence of a particular procedural effect. Likewise, the background rationale concerning esophageal injury is not a reported outcome finding from this study.
The record also illustrates why outcome definitions and analysis reporting are important. It lists active ablation procedure time as the primary outcome and total procedure time as a secondary outcome, but does not explain how those measures differ. It specifies mean and standard deviation for the primary endpoint, but does not give values or an uncertainty estimate. Those omissions prevent assessment of both the observed level and its precision.
Finally, planning illustrations and observed study results answer different questions. The registry describes assumptions for an illustrative sample-size calculation, while the completed study is single-group and its endpoint result is not reported. Planning assumptions should not be confused with evidence about the precision or success of the completed study. This separation is central to a careful statistical reading of the 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 most consequential limitation for interpreting the registry record is that numerical results for the primary and secondary procedural outcomes are not reported. The specified mean and standard deviation are not accompanied by observed values, and no confidence interval or inferential analysis is reported. This prevents assessment of the size and precision of any observed procedural pattern.
The single-group design has no like-for-like control comparison. Even a complete description of procedure time in the cooling group would not, by itself, establish what would have occurred without cooling. The registry does not report randomization, a concurrent control arm, or a comparative estimate.
Outcome definitions leave some detail unresolved. The primary endpoint is total time of active ablation procedure, while total procedure time is also listed as a secondary outcome. The registry does not report how the timing boundaries differ, how pauses enter the timing measure, or how measurements were reconciled between the clinician recorder and research coordinator. Detailed eligibility criteria, participant characteristics, and endpoint completeness are also not reported in the registry record.
The record lists no analysis records and does not report methods for missing observations, multiplicity, or analysis populations. Its adverse-event counts are not accompanied by detailed collection methods or safety follow-up information. These reporting limitations do not prove that procedures or analyses were not conducted; they mean that those details are not reported in the registry record and cannot support further conclusions.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Evaluating Active Esophageal Cooling During Cardiac Ablation Procedures — NCT04063761.
- Registry record last updated 2025-06-17; status last verified 2022-09.
- Results first posted 2022-09-07.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
The registry record describes a completed single-group device study of active esophageal cooling during left atrial radiofrequency ablation for atrial fibrillation. Enrollment is 20, masking is NONE, and allocation is NA. Participants in the Esophageal Cooling arm received the Attune Medical Esophageal Heat Transfer Device.
The primary outcome is total time of active ablation procedure, measured in hours, with mean and standard deviation specified. Secondary outcomes are total procedure time and number of procedural pauses during left atrial instrumentation. Numerical results for these outcomes are not reported in the registry record, and no analysis records are listed.
The registry lists 0 serious adverse events, 0 other adverse events, and 0 deaths in the cooling group. These descriptive counts do not constitute a comparison with another group. The record therefore identifies the study question and its outcome measures, but does not report the procedural results needed to assess their magnitude or precision.