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 Clinical Study of the CardioFocus Endoscopic Ablation System for the Treatment of Symptomatic AF (NCT00958165), a na phase 3 study. The primary outcome is Chronic Effectiveness in Treating PAF as Demonstrated by no AF Recurrences After the Blanking Period and During the 12-month Follow-up Period..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00958165 |
| Phase | Phase 3 |
| Condition | Paroxysmal Atrial Fibrillation |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 81 |
| Arms in the primary outcome | n/a |
| Lead sponsor | CardioFocus |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned participants with paroxysmal atrial fibrillation (PAF). The registry reports 81 enrolled overall. Its description of the primary endpoint refers to 72 enrolled and treated participants, of whom 67 were evaluable for that endpoint. The registry does not give further clinical or demographic details about the endpoint population.
Intervention
The intervention was the CardioFocus Endoscopic Ablation System - Adaptive Contact (EAS-AC), a device used to perform pulmonary vein isolation (PVI). The registry describes the study purpose as assessing the system's safety and effectiveness in treating PAF with PVI.
Comparator
The study is recorded as single-group, with allocation listed as not applicable. It therefore does not provide a like-for-like control comparison. The registry describes one EAS-AC group and does not report a separate control group.
Primary question
The primary endpoint was the number of participants with no AF recurrence after the blanking period and during the 12-month follow-up period. The registry record does not report how many evaluable participants met this endpoint, so it does not provide a primary effectiveness result to interpret.
3. Trial Design
This completed Phase 3 study evaluated the CardioFocus EAS-AC device for treating symptomatic atrial fibrillation. The listed condition is paroxysmal atrial fibrillation. The intervention description specifies pulmonary vein isolation with EAS-AC, and the registry's stated purpose was to determine the device's safety and effectiveness in that setting.
The design is recorded as single-group, with allocation listed as not applicable and masking listed as none. The registry describes an EAS-AC group and no control group. Consequently, the study record does not offer a randomized or otherwise like-for-like comparison between EAS-AC and another treatment or a control condition. A result from this design, if reported, would describe outcomes in the treated group; it would not by itself estimate a comparative treatment effect.
The registry reports 81 enrolled participants overall. The primary endpoint description refers to 72 enrolled and treated participants, with 67 evaluable for the chronic effectiveness endpoint. Those figures describe different populations in the record and should not be treated as interchangeable. Reasons that the endpoint-evaluable population is smaller than the enrolled-and-treated population are not reported in the registry record.
The study started in 2009-08, reached primary completion in 2012-03, and is listed as completed. The record names CardioFocus as sponsor. It does not report details about recruitment procedures, treatment delivery beyond PVI with EAS-AC, follow-up visit schedules, or the handling of protocol deviations.
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 | EAS-AC |
|---|---|
| STARTED | 81 |
| Treated | 72 |
| COMPLETED | 67 |
| NOT COMPLETED | 14 |
Reasons for not completing this period:
| Reason | EAS-AC |
|---|---|
| Lost to Follow-up | 5 |
| Not eligible | 9 |
Analysis population for the primary outcome, as defined in the registry: Of the 72 enrolled and treated participants, 67 were evaluable for the chronic effectiveness endpoint.
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.
Population: Of the 81 enrolled participants, 72 meet all enrollment criteria and were treated. These are the evaluable baseline participants
| Characteristic | Unit | EAS-AC |
|---|---|---|
| Participants analysed | 72 | |
| Age, Continuous | years | 58 (SD 10) |
| Sex: Female, Male: Female | Participants | 34 |
| Sex: Female, Male: Male | Participants | 38 |
| Region of Enrollment: Germany | participants | 72 |
6. Primary Endpoint
The registry lists the primary outcome as Chronic Effectiveness in Treating PAF as Demonstrated by no AF Recurrences After the Blanking Period and During the 12-month Follow-up Period., measured over 12 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Successful participants |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is described as chronic effectiveness, measured by the number of participants with no AF recurrence after the blanking period and during the 12-month follow-up period. The unit is successful participants, and the measure is a number rather than a time-to-event estimate. The record identifies 67 participants as evaluable for this endpoint among the 72 enrolled and treated participants described in the endpoint population.
In general, a recurrence-based endpoint can summarize whether the targeted condition returned during a specified follow-up interval. A blanking period separates an initial period from the later interval used to assess recurrence; the registry title defines the assessment as occurring after that period. The record does not specify the blanking period's duration or provide further details about how recurrence was defined or ascertained. Those details are not reported in the registry record.
The endpoint is useful for describing the study's stated effectiveness question, but its interpretation depends on having a reported outcome count and a clear understanding of the population assessed. The registry record gives the endpoint definition and evaluable population, but does not report the number of successful participants. It therefore does not permit calculation or interpretation of the observed endpoint result from the information recorded.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry sets out a clinically focused endpoint: the number of evaluable participants with no AF recurrence after the blanking period and during the 12-month follow-up period. It also identifies the population used for that endpoint as 67 evaluable participants, from 72 enrolled and treated participants. However, it does not report the number who met the endpoint. Without that outcome count, the primary effectiveness result cannot be described, and its precision cannot be assessed from this record.
This missing outcome value is central. The endpoint title alone is not evidence that participants did or did not remain free of recurrence. Nor does the number of evaluable participants indicate how many were successful. The record therefore supports an account of the question the study set out to assess and of the stated endpoint population, but not a conclusion about the endpoint's observed result.
The single-group design also limits what an outcome could establish. In general, results from a treated group describe outcomes observed under that study's conditions. Without a control group, they do not separate the intervention's contribution from other influences on outcomes, including the natural course of the condition, concurrent care, or factors related to participant selection. These are general limitations of uncontrolled comparisons, not findings about what occurred in this study.
The study is listed as unmasked. In general, lack of masking can affect how outcomes are assessed or reported, particularly when assessment involves judgment. The registry does not describe endpoint adjudication or other safeguards that might reduce such influence. It is not possible to determine from the record whether or how these considerations affected the study.
The safety record lists 10 participants with serious adverse events among 72 at risk, and 0 with other adverse events among 72 at risk. These are safety summaries, not a substitute for the missing primary endpoint. The listed serious-event terms have percentages, but the registry does not state their denominators or provide event-level detail. The safety information should therefore be read as a limited registry summary rather than as a complete characterization of risk.
The record lists zero analyses and does not report a primary outcome estimate, confidence interval, or statistical test. It is consequently not possible to assess statistical uncertainty around effectiveness, whether any planned hypothesis was tested, or how the observed result relates to a target effect. Planning illustrations based on an observed effect, where presented, are not the trial's design or observed power; the registry does not report the numerical primary result needed to interpret such illustrations.
9. Statistical Methods Explained
What does a count endpoint express?
The primary endpoint is a count of successful participants: those with no AF recurrence after the blanking period during the 12-month follow-up period. A count answers how many people in the defined endpoint population met the stated criterion. In general, counts are easiest to interpret alongside the population assessed and a clear definition of success. Here, the registry identifies 67 evaluable participants, but does not report the success count. As a result, the count's magnitude and its uncertainty cannot be evaluated from the record.
The endpoint title describes a period during which recurrence is assessed. This differs conceptually from a measure that records the time until recurrence: a count of participants meeting a criterion does not, by itself, show when any recurrence occurred. In general, event timing can contain information that a simple count does not preserve. The registry does not report a time-to-event primary analysis; its listed outcome is a number of successful participants.
What would a confidence interval add?
In general, a confidence interval describes the statistical uncertainty around an estimate, under the assumptions of the method used. It is not a guarantee that the true value lies within a particular interval. For a count-based endpoint, an interval is commonly interpreted with an estimate of the underlying success frequency or another specified measure, as appropriate to the analysis. The registry record does not report an endpoint estimate or confidence interval, so no such precision assessment can be made for the primary outcome.
The width of an interval depends on the amount of information and on the variability of the data, as well as on the statistical method. More information can often yield greater precision, but the number evaluable alone does not determine a result or its exact precision. The outcome count and analysis method matter, and neither is reported for the primary endpoint in this record. No interval should be inferred from the evaluable population.
Why does the study design matter?
In general, a single-group study estimates outcomes observed among participants receiving the intervention, subject to the way participants were selected, treated, followed, and assessed. A control group can provide a concurrent reference for interpreting differences, while random allocation can help balance measured and unmeasured baseline factors in expectation. This study is recorded as single-group, with allocation not applicable, so it does not provide a randomized treatment contrast. A within-group outcome, even if it had been reported, would not be equivalent to a comparative effect estimate.
The record also lists masking as none. In general, masking can reduce the possibility that knowledge of treatment influences care, participant reporting, or outcome assessment. Its importance depends on the outcome and the assessment process. Since the registry does not report further information about endpoint ascertainment, adjudication, or safeguards, the role of these procedures cannot be evaluated from the record.
How should planning illustrations be read?
In general, a sample-size calculation asks how many participants a future study would require under specified assumptions about the target effect, significance level, allocation, and statistical model. It is a planning exercise, not a statement about the power achieved by an already completed study. The registry's planning assumptions describe illustrations based on an observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect.
Those assumptions do not describe this study's recorded single-group design: the illustrations assume two arms, whereas the registry lists one group and no comparison. They therefore should not be interpreted as the study's original design or as an observed-power result. The registry record does not report the numerical primary outcome result needed to understand the observed effect that underlies such planning illustrations. No numerical planning result or sample-size requirement is stated in this narrative.
The record also notes that time-to-event planning tables use the total number of events, while other planning tables use participants per arm. In general, these quantities have different meanings: event totals concern information from events over follow-up, while participants per arm refer to allocation in a two-arm design. The primary endpoint in this record is a count of successful participants, not a reported time-to-event estimate. The registry does not provide enough primary outcome detail to derive a planning target or assess the assumptions' relevance to this endpoint.
Why can over-dispersion matter in general?
For count outcomes, a simple statistical model may assume that variation follows a particular relationship to the mean. Over-dispersion means the observed variability is greater than that assumption allows. If it is ignored, standard errors and confidence intervals may be too small, and tests may appear more certain than the data warrant. This is a general issue in count-data analysis; the registry does not report an over-dispersion assessment, a count model, or a statistical analysis for the primary endpoint. It is therefore not possible to say that over-dispersion was present or that a particular method was used.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and zero analyses. It does not report a statistical analysis plan, hypothesis-testing strategy, or multiplicity adjustment. Because no primary outcome result or statistical test is reported, the record does not show whether the endpoint was analyzed as prespecified or whether additional analyses were conducted outside the registry entry. The handling of multiple comparisons is not reported in the registry record.
The endpoint population is described as 67 evaluable participants among 72 enrolled and treated participants. The reasons for non-evaluability, and any differences between evaluable and non-evaluable participants, are not reported. The registry also does not describe how missing follow-up information was handled, whether participants with incomplete follow-up were classified as unsuccessful, or whether any imputation or sensitivity analysis was used. These omissions matter because missing outcome information can affect both the estimated result and how broadly it applies.
The record does not provide an analysis population definition beyond the endpoint description. It does not state whether the primary analysis followed an intention-to-treat principle, a treated-population principle, or another rule. The endpoint wording refers to the participants evaluable for chronic effectiveness, but does not explain how evaluability was determined.
Consequently, the reported endpoint population can be identified, but the path from enrollment and treatment to endpoint analysis cannot be reconstructed. The registry provides too little information to assess attrition, missing-data assumptions, multiplicity control, or robustness of the primary result.
11. 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 |
|---|---|---|---|
| EAS-AC | 10 | 72 | 13.9% |
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 |
|---|---|
| EAS-AC | 0 of 72 |
Most frequent serious adverse event terms
| Event term | Organ system | EAS-AC |
|---|---|---|
| Pericardial tamponade | Cardiac disorders | 4 of 72 |
| Pericardial effusion | Cardiac disorders | 3 of 72 |
| Air embolism | Cardiac disorders | 2 of 72 |
| Phrenic nerve injury | Musculoskeletal and connective tissue disorders | 1 of 72 |
Serious events with the highest arm-level rate: pericardial tamponade (5.6%), pericardial effusion (4.2%), air embolism (2.8%), phrenic nerve injury (1.4%).
The registry lists 10 participants with serious adverse events among 72 at risk in the EAS-AC group. It lists 0 participants with other adverse events among 72 at risk. These figures describe separate registry categories; the entry does not explain their operational definitions or how events were classified. They should not be combined or interpreted as a complete count of all events.
The registry also lists serious adverse event terms with percentages: pericardial tamponade, 5.6%; pericardial effusion, 4.2%; air embolism, 2.8%; and phrenic nerve injury, 1.4%. The record does not state the denominator used for these percentages or provide event counts for each term. The terms may describe events rather than people, and the record does not clarify whether participants could contribute more than one event or term. These percentages therefore should not be used to infer participant counts or added together.
Deaths are not reported in the registry record. The safety summary does not provide timing, duration, severity grading beyond the serious-event category, relatedness to the device, or details of follow-up. In general, adverse-event summaries are most informative when their definitions, denominators, observation period, and assessment procedures are clear. Those details are not available in this entry, so the listed figures represent a limited registry account rather than a full safety analysis.
12. What the Result Does, and Does Not, Mean
The record establishes what the study set out to assess: chronic effectiveness of EAS-AC PVI for PAF, using absence of AF recurrence after the blanking period during the 12-month follow-up period as the primary endpoint. It also establishes the endpoint population described in the registry: 67 evaluable participants from 72 enrolled and treated participants. The study is listed as completed, and the design is single-group and unmasked.
The record does not establish the observed primary effectiveness result. It does not report how many participants met the endpoint, an estimated success frequency, a confidence interval, or a statistical test. Without those results, the direction, size, and precision of the primary outcome cannot be described. The endpoint wording expresses the criterion for success, not the finding.
Even a reported outcome from this single-group design would have had a limited comparative interpretation. In general, without a control group, an observed outcome cannot isolate the intervention's effect from other possible explanations. The record contains no randomized contrast and no comparator outcome. It therefore cannot support a direct claim about how EAS-AC compares with another treatment or with no intervention.
The safety summary records serious adverse events and lists several event terms, but lacks detail about event definitions, percentage denominators, timing, and relationship to the device. Those data can be described as recorded, but they do not constitute a comprehensive assessment of safety. The registry also does not report deaths.
In short, the registry allows readers to understand the study's design, intended endpoint, and limited safety summary. It does not provide enough outcome or analysis detail to determine the primary endpoint result, its uncertainty, or a comparative treatment effect. No conclusion that the device does or does not work follows from the information recorded.
13. Why This Trial Matters Statistically
This trial is statistically notable because its registry combines a clearly stated clinical endpoint with a single-group design and no posted primary outcome value. Those features illustrate the difference between knowing what a study intended to measure and being able to evaluate what it found. A precise endpoint definition is necessary for interpretation, but an outcome count and analysis details are also needed.
The endpoint population information is useful: the record identifies 67 evaluable participants from 72 enrolled and treated participants. Yet without the number who met the no-recurrence criterion, readers cannot estimate the endpoint outcome or its statistical uncertainty. This is a practical example of why denominators alone do not supply an effectiveness result.
The design also demonstrates why statistical language should match the evidence structure. A single-group study can report outcomes in the treated group, but it cannot provide the same comparative inference as a controlled design. No amount of precision around a within-group estimate would, by itself, create a randomized comparison or remove the need for an appropriate reference group.
The entry also shows why safety summaries need context. Counts and percentages are difficult to interpret without definitions, denominators, and information about whether figures refer to people or events. The registry lists serious-event categories and terms, but leaves key interpretive details unreported.
Finally, planning calculations should be distinguished from trial results and design choices. The registry describes planning assumptions involving two arms, while the recorded study is single-group. Such illustrations can be useful for considering future research under explicit assumptions, but they do not establish observed power or recover the missing primary result.
14. 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 direct limitation of the registry entry is that it does not report the primary endpoint count. Although the endpoint is defined and the evaluable population is identified, the number of successful participants, an estimate of outcome frequency, and measures of precision are not reported in the registry record. This prevents quantitative interpretation of chronic effectiveness.
The single-group design has no like-for-like control comparison, and masking is listed as none. The record therefore cannot support a randomized contrast, and it does not describe procedures for blinded endpoint assessment or independent adjudication. Whether such procedures existed is not reported in the registry record.
Several details necessary to understand the endpoint are absent. The duration of the blanking period, the operational definition of AF recurrence, the method of recurrence detection, and the handling of incomplete follow-up are not reported. The reasons that some enrolled and treated participants were not listed as evaluable are also not reported.
The safety summary provides limited context. It gives counts for serious and other adverse events at risk and lists serious-event terms with percentages, but the denominators for those percentages, event-level counts, timing, relatedness, and assessment methods are not stated. Deaths are not reported in the registry record.
Finally, the record lists zero analyses and does not describe a statistical analysis plan, multiplicity handling, missing-data methods, or an analysis population beyond the endpoint-evaluable description. The planning assumptions refer to a two-arm framework that is not the recorded single-group design. Together, these omissions restrict assessment of both the reported evidence and the methods that would be needed to interpret it fully.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Clinical Study of the CardioFocus Endoscopic Ablation System for the Treatment of Symptomatic AF — NCT00958165.
- Registry record last updated 2016-08-30; status last verified 2016-07.
- Results first posted 2016-07-27.
- 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.
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18. Record Summary
The registry describes a completed Phase 3, single-group study of the CardioFocus EAS-AC device for PAF, using pulmonary vein isolation. It lists 81 enrolled participants overall. The primary endpoint concerns no AF recurrence after the blanking period during the 12-month follow-up period; the endpoint population is described as 67 evaluable participants among 72 enrolled and treated participants.
The primary endpoint result is not reported in the registry record. Allocation is listed as not applicable, masking as none, and the record lists zero analyses. Safety information includes 10 participants with serious adverse events among 72 at risk and 0 with other adverse events among 72 at risk. Serious-event terms and percentages are listed, but their denominators are not reported. The study started in 2009-08, reached primary completion in 2012-03, and is listed as completed.