Atrial Flutter Ablation With Contact Therapy Cool Path Ablation System Along With EnSite Velocity Contact System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Atrial Flutter Ablation With Contact Therapy Cool Path Ablation System Along With EnSite Velocity Contact System (NCT01401361), a na phase 3 study. The primary outcome is Primary Safety:Incidence of Composite, Serious Adverse Events Within 7 Days Post Procedure.

2. Clinical Question

3. Trial Design

This completed phase 3 study evaluated a device-based treatment for typical atrial flutter. Its title and intervention description identify an ablation system combining the Contact Therapy Cool Path catheter with EnSite Velocity Contact technology. The treatment description also lists a 1500 T9 V1.43 RF Generator, Model 1611 connection cable, EnSite Velocity Contact Kit, and EnSite Velocity Contact software controlled via entitlement.

The registry identifies the study model as single-group. Allocation is listed as NA, and masking as none. No control arm or randomized comparison is reported. Accordingly, the registry outcome is a description of events in the treated group, not a treatment effect estimated against a concurrent comparator.

The record reports enrollment of 150 subjects who met inclusion and exclusion criteria. It states that 16 subjects withdrew before use of the investigational device and that 134 were treated. The primary safety result is reported for the treated group. The timing fields list a start of 2011-10, primary completion of 2012-04, and status of completed. Abbott Medical Devices is identified as the sponsor.

The stated study objective concerned both intraprocedural composite serious adverse events and whether ablation efficacy was affected. The primary safety outcome is described as composite serious adverse events within 7 days after the procedure. The registry lists Secondary Efficacy among the secondary outcomes, but detailed efficacy results are not reported in the registry record. Other protocol details, including the full eligibility criteria and treatment procedures, 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 150 subjects who met Inc/Excl criteria were enrolled. 16 subjects were withdrawn prior to the use of the investigational device, thus,134 were treated. 3 subjects had composite adverse events that were serious and occurred within 7 days of the ablation procedure. These events are part of the primary safety endpoint analysis per protocol.

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 Primary Safety:Incidence of Composite, Serious Adverse Events Within 7 Days Post Procedure, measured over 7 days.

The primary endpoint is the incidence of composite serious adverse events within 7 days after the ablation procedure. The registry defines the events without requiring a determination that they were related to the device. The reported result is 3 treated participants with a qualifying event among 134 treated participants.

A safety endpoint of this kind records whether a defined adverse event occurred during a specified observation period. The composite combines events under a single endpoint, so its overall count gives a broad summary rather than a separate estimate for each possible event type. The listed serious-event terms include Congestive Heart Failure, Intermittent High Grade AV Block, and Transient Ischemic Attack, each reported as 0.7%. The record does not provide the full component definitions or event-level detail needed to interpret the composite beyond its stated definition.

Regardless of device relatedness, as specified in the endpoint definition, helps distinguish the occurrence of serious events from a judgment about their cause. That approach can capture events during the defined period without excluding them based on an attribution decision. It does not, by itself, establish that the device caused an event. The endpoint’s short stated observation window also defines what this primary safety result covers; outcomes outside that period are not described by this endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count represent?

The primary outcome is binary at the participant level: a treated participant either had a qualifying composite serious adverse event within the stated period or did not. The registry reports the number with an event and the number treated. A count is directly interpretable as the number of participants meeting the endpoint definition, but it does not express uncertainty by itself.

General statistical explanation: an event proportion relates the number of participants meeting an endpoint to the number assessed for that endpoint. Its interpretation depends on a clearly defined numerator, denominator, population, and observation period. Here, the record identifies 3 participants with the primary event and 134 treated participants, and defines the period as 7 days after the procedure. No additional proportion is calculated in this explanation.

What would a confidence interval add?

General statistical explanation: a confidence interval conveys statistical uncertainty around an estimate. A narrower interval indicates greater precision under the assumptions of the method; a wider interval indicates less precision. It does not guarantee that the true value lies within the interval, and it does not address bias from study design or incomplete outcome information. Confidence intervals for the primary safety result are not reported in the registry record, so its precision cannot be described numerically from the record.

A single-group result can describe the event frequency in the observed treatment group. It cannot estimate a difference from an unobserved or unreported control group. Even a precise estimate for the treated group would not resolve whether the event experience differs from what would have occurred under another treatment or without the device. Such a comparison requires an appropriate comparator and a prespecified analytical approach; neither a comparator nor the statistical plan is reported in the registry record.

What does the composite endpoint combine?

General statistical explanation: a composite endpoint groups multiple event types under a common outcome definition. This can summarize a broader safety question, but the total may be driven by components that differ in frequency, clinical importance, or mechanism. Component-level results help readers understand what contributes to the composite. The registry names three serious-event terms, each with a reported value of 0.7%, but does not report the full component definitions or event-level information in the available record.

The endpoint counts events regardless of whether a determination can be made about device relatedness. That rule makes the endpoint definition independent of an attribution judgment. It does not show that each event was caused by the procedure or device. The registry does not report the causality assessments for the listed events.

How should the planning assumptions be read?

General statistical explanation: sample-size planning asks how many participants a future study might need to detect a specified effect under chosen assumptions. It is different from evaluating how much power the completed study had after observing its results. Planning figures based on the observed effect are illustrations, not observed power and not evidence that the study was designed with those assumptions.

The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a fraction of the observed effect. Those assumptions do not describe the reported single-group design, for which no two-arm allocation or comparison is given. The sample-size justification and the study’s own statistical plan are not reported in the registry record. No planning figure should be interpreted as the trial’s actual design target unless the record documents that connection.

What analyses are reported?

The registry lists 0 analyses. It therefore does not report an inferential analysis, adjustment method, confidence interval, or hypothesis test for the primary outcome in the information. General statistical explanation: analysis choices can affect how an estimate is calculated and how uncertainty is represented. Without a reported plan and analysis, readers cannot determine whether the posted count was part of a prespecified analysis or whether other analytical decisions were made.

The record identifies the primary safety outcome and a secondary efficacy outcome, but the detailed definitions, analysis populations, and handling of incomplete outcomes are not reported in the registry record. Those omissions limit the ability to reproduce or independently assess the analysis.

10. Exact Estimates for Each Arm

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

R code and output

arm    <- c("Treatment Arm")
n      <- c(134)
events <- c(3)
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  Treatment Arm  134  3  2.2  0.5  6.4  0.8  6.4  0.8  6.4

11. Multiplicity, Missing Data and Analysis Populations

The registry reports 3 outcome measures and identifies Secondary Efficacy as a secondary outcome. The primary safety endpoint is the composite incidence of serious adverse events within 7 days after the procedure. Detailed definitions and results for the efficacy outcome are not reported in the registry record. The record lists 0 analyses, and it does not describe a statistical plan for testing or interpreting the outcomes.

General statistical explanation: when a study evaluates multiple outcomes or makes multiple statistical comparisons, the chance of an apparently notable result can increase if each is assessed separately without an appropriate plan. A multiplicity strategy may define which outcomes are primary, how testing is ordered, or how error rates are handled. No multiplicity approach is reported in the registry record, so it is not possible to determine whether or how this issue was addressed.

Missing-data handling is also not reported. The registry states that 16 enrolled subjects withdrew before use of the investigational device and that 134 were treated. It does not provide reasons for withdrawal or outcome status for those who withdrew. The primary safety result is reported for the treated group, but the record does not explain how missing outcome information, if any, was handled.

The description does not specify additional analysis populations, such as whether the primary safety analysis included all treated participants or used any further exclusions. The available numbers identify the treated group and the reported endpoint count, but do not establish the full analysis rules. These gaps constrain interpretation of the outcome and reproducibility of the analysis.

12. Safety Results

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

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: congestive heart failure (0.7%), intermittent high grade av block (0.7%), transient ischemic attack (0.7%).

The serious adverse-event summary reports 3 affected participants among 134 at risk in the Treatment Arm. The primary endpoint refers to composite serious adverse events within 7 days after the procedure, regardless of whether device relatedness could be determined. The summary also lists 10 participants with other adverse events; the registry record does not explain the overlap or classification relationship between these other events and the primary endpoint.

Congestive Heart Failure, Intermittent High Grade AV Block, and Transient Ischemic Attack are each listed at 0.7% among the top serious terms. Those percentages are reported as term-level summaries; they should not be added together or treated as a complete account of all serious events. The record does not give additional event-level detail or the number of participants represented by each term in the available description.

General statistical explanation: adverse-event counts are descriptive. They do not establish causation, and without a comparator they cannot show whether the observed experience differs from another treatment or background risk. Deaths are not reported in the registry record. The stated primary safety window is 7 days; information about events outside that window is not part of this endpoint result.

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

The result describes the reported short-term safety experience among participants treated with the investigational device system. Specifically, the registry reports 3 participants with composite serious adverse events within 7 days after the procedure among 134 treated participants. The endpoint includes serious events regardless of whether a device-relatedness determination could be made.

This is a descriptive observation from a single-group study. Because no comparator is reported, the result cannot establish how the event experience compares with another ablation system, another procedure, or no treatment. It also cannot isolate the contribution of the catheter, the accompanying technology, the procedure, or participants’ underlying condition to any event. The registry does not report causal assessments for the events.

The result does not answer the efficacy question. Although the study objective refers to efficacy and the record lists Secondary Efficacy, detailed efficacy results are not reported in the registry record. The safety count alone cannot demonstrate whether the procedure was effective or whether efficacy was affected.

The count also does not convey statistical precision without an interval estimate or other uncertainty measure. No confidence interval or inferential analysis is reported in the registry record. The reported event terms and percentages offer some information about the types of serious events listed, but the full component definitions and event-level details are not available in the registry record.

General statistical explanation: interpreting a safety result requires attention to the endpoint definition, the population counted, the observation window, and the study design. Those features determine what the result can describe. Here, the information supports a description of the treated group within the stated period, not a causal or comparative conclusion.

14. Why This Trial Matters Statistically

This study illustrates an important distinction between a safety count and a comparative treatment effect. The registry reports a count for a defined composite endpoint in a treated group, while identifying the design as single-group and reporting no comparator. Such a result can document what occurred in the observed group, but it does not establish whether that experience is different from an alternative.

The endpoint definition also matters. Serious adverse events are counted within 7 days after the procedure and regardless of whether device relatedness can be determined. This makes the endpoint a defined observation of short-term events rather than a judgment that the device caused those events. Reading the result accurately requires keeping those two ideas separate.

The record also demonstrates why enrollment and analysis populations should not be treated as interchangeable. It reports 150 enrolled subjects, 16 withdrawals before use of the investigational device, and 134 treated participants. The primary safety summary uses the treated group, while reasons for withdrawal and the subsequent outcome status of those who withdrew are not reported.

Finally, the record’s limited statistical detail is itself relevant to interpretation. It lists 0 analyses and does not report confidence intervals, a statistical plan, or detailed efficacy findings. These omissions make it difficult to assess precision, reproduce the analysis, or connect the posted safety count to the broader study objective. The result is therefore most useful as a bounded descriptive finding, with its population, endpoint, and time window kept explicit.

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 single-group design is the central limitation for comparative interpretation. Allocation is listed as NA, masking as none, and no comparator is reported. The observed event count therefore cannot establish how safety outcomes would compare under another treatment or control condition. It also cannot separate effects associated with the device from those associated with the procedure or other factors.

The primary endpoint is a composite and is limited to serious adverse events within 7 days after the procedure. The record does not report the complete component definitions or event-level details. The listed serious terms provide some context, but their percentages do not replace a complete account of how the composite was formed. Device relatedness was not required for an event to count, and event-level attribution is not reported.

The participant flow raises questions the registry does not resolve. The record reports 150 enrolled subjects, 16 withdrawals before device use, and 134 treated participants. Withdrawal reasons and outcome status for those who withdrew are not reported in the registry record. The record also does not explain whether there were missing outcomes among treated participants or how any missing information was handled.

Detailed efficacy findings are not reported, despite the stated interest in efficacy and the listing of Secondary Efficacy. The statistical analysis plan, confidence intervals, hypothesis tests, multiplicity approach, sample-size justification, and further analysis-population rules are not reported in the registry record. Follow-up information beyond the primary endpoint’s 7-day period is also not reported in the available record. These gaps limit assessment of precision, reproducibility, and the broader safety and efficacy context.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Atrial Flutter Ablation With Contact Therapy Cool Path Ablation System Along With EnSite Velocity Contact System — NCT01401361.
• Registry record last updated 2019-02-15; status last verified 2019-01.
• Results first posted 2013-12-23.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes a completed phase 3, single-group device study of ablation for typical atrial flutter, sponsored by Abbott Medical Devices. The listed study start is 2011-10, and primary completion is 2012-04. The treatment combined the Contact Therapy Cool Path ablation catheter with EnSite Velocity Contact technology and the other listed system components.

The primary safety endpoint was composite serious adverse events within 7 days after the procedure, regardless of device relatedness. The record reports 3 affected participants among 134 treated participants. It also reports 150 enrolled subjects and 16 withdrawals before use of the investigational device.

No comparator is reported. Detailed efficacy results, inferential analyses, confidence intervals, missing-data methods, and the statistical plan are not reported in the registry record. The posted safety result is therefore descriptive for the treated group and the specified observation period.