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 Evaluation of the FreedomFlow™ Orbital Atherectomy System to Treat Peripheral Artery Disease (NCT03635190), a na na study. The primary outcome is Technical Success.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03635190 |
| Phase | NA |
| Condition | Peripheral Arterial Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 112 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Cardio Flow, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with peripheral arterial disease and de novo native target lesions in the lower-extremity peripheral vasculature. The primary endpoint population was 154 distinct lesions in 112 patients. Because some patients contributed more than one lesion, the lesion count and patient count describe different units; they should not be treated as interchangeable.
Intervention
The intervention was the Cardio Flow FreedomFlow™ Orbital Circumferential Atherectomy System, described in the registry as orbital circumferential atherectomy. The stated purpose was to evaluate plaque removal and modification of vessel compliance in the target lesions. The registry record does not report additional procedural details beyond the endpoint definition.
Comparator
There was no parallel control group. The study is registered as a single-group study, with allocation listed as NA and masking listed as none. Consequently, the results cannot provide a like-for-like comparison against another device, a different procedure, or no intervention. Any interpretation is limited to outcomes recorded for the treated group.
Primary question
The primary question was whether the system could achieve technical success at the lesion level during the index procedure. Success was defined as residual diameter stenosis ≤50% without adjunctive therapy, assessed at the time of the procedure, usually within one hour after starting it. The registry record does not report how many lesions met this definition or an estimate of the success rate. It therefore does not allow the primary question to be answered quantitatively from the posted primary result.
3. Trial Design
This was a completed, single-group device study of orbital circumferential atherectomy for peripheral artery disease. The registry lists an enrollment of 112, an allocation of NA, and no masking. The intervention arm is described as orbital circumferential atherectomy. No randomized control arm is identified, so the trial is not a randomized comparison and its outcomes should not be interpreted as an estimate of the difference between treatments.
The primary outcome was technical success measured per lesion. The primary endpoint population comprised 154 distinct lesions in 112 patients. These are not equivalent units of observation: a patient could contribute multiple lesions. If lesion outcomes within a patient are associated, analyses that treat every lesion as independent may understate uncertainty. The registry record does not report whether or how any analysis accounted for this possible within-patient dependence.
The study start date is 2018-12-17, the primary completion date is 2021-03-24, and the status is completed. The phase is listed as NA. The sponsor is Cardio Flow, Inc. The registry also lists nine outcome measures. Secondary outcomes include clinical success, procedure success, ankle brachial index at baseline, 30 days and 6 months, Rutherford classification, VascuQoL at baseline, 30 days and 6 months, target lesion and vessel revascularization, and vessel patency.
The registry record does not report a randomized allocation scheme, a masked assessment process, or a comparator. It also does not report the protocol’s sample-size justification, analysis plan, or criteria for selecting the analysis population. The record’s completion status indicates that the study is marked completed; it does not by itself establish that every planned outcome was reported or that the primary endpoint result is available.
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 | Atherectomy Treatment Per Lesion |
|---|---|
| STARTED | 112 |
| COMPLETED | 103 |
| NOT COMPLETED | 9 |
Reasons for not completing this period:
| Reason | Atherectomy Treatment Per Lesion |
|---|---|
| Lost to Follow-up | 4 |
| Death | 3 |
| Withdrawal by Subject | 1 |
| Patient moved and did not return for follow up | 1 |
Analysis population for the primary outcome, as defined in the registry: 154 distinct lesions in 112 patients were analyzed
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: Some patients had multiple lesions treated. Treatment results for 2 lesions were not evaluable or not reported
| Characteristic | Unit | Interventional Treatment |
|---|---|---|
| Participants analysed | 112 | |
| Age, Continuous | years | 70.1 (SD 9.8) |
| Sex: Female, Male: Female | Participants | 45 |
| Sex: Female, Male: Male | Participants | 67 |
| Race/Ethnicity, Customized: Asian | Participants | 1 |
| Race/Ethnicity, Customized: Black or African Origin | Participants | 16 |
| Race/Ethnicity, Customized: Caucasian | Participants | 86 |
| Race/Ethnicity, Customized: Hispanic or Latino | Participants | 7 |
| Race/Ethnicity, Customized: Native American or Alaskan Native | Participants | 1 |
| Race/Ethnicity, Customized: Not Reported | Participants | 1 |
| Region of Enrollment: United States | participants | 112 |
| Rutherford Classification: 2 Moderate Claudication | Participants | 9 |
| Rutherford Classification: 3 Severe Claudication | Participants | 55 |
| Rutherford Classification: 4 Ischemic Rest Pain | Participants | 34 |
| Rutherford Classification: 5 Minor Tissue Loss | Participants | 14 |
6. Primary Endpoint
The registry lists the primary outcome as Technical Success, measured over At the time of the index procedure, usually within one hour after starting the procedure.
| Element | Registry entry |
|---|---|
| Result type | Count Of Units |
| Measure of spread | not applicable |
| Unit | lesion |
| Endpoint classification | not reduced to a single comparison |
Technical success is a procedural endpoint defined at the lesion level. A lesion meets the stated definition if the FreedomFlow™ system achieves residual diameter stenosis ≤50% without adjunctive therapy. The assessment is tied to the index procedure and is described as occurring usually within one hour after the procedure starts. The outcome is therefore focused on an immediate technical result, rather than on a later clinical event or a patient-reported outcome.
Such an endpoint can be useful for assessing whether a device achieves a specified procedural objective. A threshold makes the success criterion explicit, while the restriction on adjunctive therapy distinguishes success attributed to the device procedure from an outcome requiring additional treatment. As a general statistical point, a binary lesion-level endpoint can be reported as a count meeting the criterion and a proportion of the assessed lesions, with an interval conveying uncertainty. The registry record does not report the numerator, proportion, or interval for technical success, so none can be interpreted from the posted primary result.
The primary population includes 154 distinct lesions in 112 patients. This matters because the endpoint is defined for lesions, while clinical outcomes and safety events may be recorded for patients. Multiple lesions in one patient can share clinical and procedural circumstances. A lesion-level analysis may therefore require methods that account for clustering if the observations are not independent. The registry record does not report whether such methods were used.
Technical success is not the same as long-term vessel patency, avoidance of revascularization, improvement in symptoms, or overall safety. Those outcomes are listed separately among the secondary measures. Each addresses a different aspect of the study and may have a different assessment time. The primary endpoint should be interpreted according to its stated procedural definition, not as a substitute for those other outcomes.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical limitation is that the registry record defines the primary endpoint but does not report its result. It states that 154 distinct lesions in 112 patients were analyzed, but gives no number of lesions meeting the technical-success criterion, no proportion, and no confidence interval. The available record therefore does not quantify how often the device met the specified threshold. An enrollment count or analysis-population size alone cannot supply that missing outcome.
The definition is specific: residual diameter stenosis ≤50% without adjunctive therapy at the index procedure, usually within one hour after starting it. That definition helps clarify what the endpoint represents, but it does not establish the frequency of success. Nor does the endpoint itself describe later vessel patency, repeat revascularization, functional status, or quality of life. Those are separate outcomes in the registry.
The study has a single group and no control group. Its observations can describe outcomes recorded among participants who received the intervention, but cannot by themselves distinguish the device’s contribution from other factors that may influence procedural outcomes. No randomized treatment contrast is available. The registry record also does not report an adjusted comparison or a prespecified benchmark against which technical success was to be judged.
The unit distinction is important. The endpoint population contains more lesions than patients, meaning that multiple lesions were represented for at least some patients. Lesions from the same person may have related features or outcomes. As a general statistical matter, treating correlated lesions as fully independent can make uncertainty appear smaller than it is. The registry record does not report the statistical handling of this clustering, so the degree to which it was addressed cannot be assessed.
There are nine outcome measures listed, including measures assessed at baseline, 30 days, and 6 months. Multiple outcomes and assessment times can create multiple opportunities to observe a noteworthy result. Whether the investigators prespecified a hierarchy, adjusted for multiplicity, or distinguished confirmatory from exploratory analyses is not reported in the registry record. The number of analyses reported in the registry is zero, which leaves no posted analysis estimates to compare or interpret.
The safety record lists 112 participants at risk in the intervention group, 32 affected by serious adverse events, 71 affected by other adverse events, and 3 deaths. It also lists serious-event terms with percentages, including Other at 14.3%, Anemia at 4.5%, Infection, local at 3.6%, Target Lesion Revascularization at 3.6%, Distal Embolization at 2.7%, and Amputation below the knee at 1.8%. These entries describe reported events; without a control group, they do not estimate comparative risk or establish that the intervention caused a particular event.
Sample-size planning illustrations are not observations from this trial and are not the trial’s own design justification. The stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as fractions of the observed effect. For time-to-event outcomes, the illustrations concern total events; other illustrations concern participants per arm. The trial itself is single-group, and those hypothetical planning assumptions should not be mistaken for its actual design or for observed power.
9. Statistical Methods Explained
Technical success is a count-based endpoint with lesions as the unit. The criterion classifies a lesion according to whether residual diameter stenosis is ≤50% without adjunctive therapy. In a complete report, the count meeting the criterion and the number assessed would support a descriptive success proportion. A confidence interval would express the uncertainty around that estimate: in general, it indicates a range of values compatible with the data under the method’s assumptions. Neither the success count nor its uncertainty is reported in the registry record, so there is no primary estimate to assess for precision.
What does the unit of analysis mean?
The registry identifies 154 distinct lesions in 112 patients for the primary outcome. The endpoint’s unit is the lesion, not the patient. If a person contributes multiple lesions, those observations may be correlated because they share patient-level characteristics and circumstances. General statistical methods for clustered data can account for such dependence; treating correlated observations as independent can lead to uncertainty estimates that are too narrow. The registry record does not report whether clustering was assessed or handled, or whether all 154 lesions entered the same analysis.
Patient-level safety outcomes have a different unit from the lesion-level primary endpoint. The serious and other adverse-event summaries list participants at risk and participants affected. These counts should not be combined with lesion counts. An event term and a participant count also answer different questions: a participant can potentially experience more than one event, and the registry record does not say whether listed event categories overlap. Percentages attached to serious-event terms describe the registry’s reported terms and should not be added together as if they were mutually exclusive groups.
Why does a single group affect interpretation?
A single-group study can describe the outcomes observed among participants receiving an intervention. It does not supply a concurrent control outcome. In general, a comparison between treatment groups helps separate differences associated with treatment assignment from background changes, patient characteristics, and other influences. Without a comparator, descriptive results cannot establish how outcomes would have differed under another treatment or no intervention. Allocation is listed as NA, and the study model is single group; no randomized comparison is reported.
Masking is listed as none. In general, masking can reduce the influence of expectations on some assessments or decisions, depending on what is masked and how outcomes are measured. The registry record does not report further details about outcome-assessor masking or other safeguards. The technical endpoint uses a stated procedural threshold, but the record does not report how residual stenosis was assessed or adjudicated.
What can be learned from the planning illustrations?
The registry’s planning illustration assumptions are distinct from the study’s observed results and from its design justification. They specify a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect defined as a stated fraction of the observed effect. For time-to-event outcomes, the illustrations use total events under a Schoenfeld approach; other illustrations express participants per arm for 80% or 90% power, if such values are displayed. The actual trial is registered as single group, so the two-arm assumptions are hypothetical planning conditions, not a description of the enrolled study.
General power calculations estimate how often a planned statistical test would detect a specified effect under stated assumptions. They are planning tools, not evidence that a study did or did not find an effect. A sample-size illustration based on an observed effect is especially not observed power: it answers a hypothetical design question using the effect estimate as an input. Such illustrations do not replace the original protocol’s rationale, which is not reported in the registry record. The registry entries do not give numerical planning outputs to interpret.
How should repeated outcomes be considered?
The registry lists nine outcome measures, with several secondary outcomes assessed at baseline, 30 days, and 6 months. As a general principle, testing many outcomes or time points can increase the chance of at least one apparently unusual result when no true difference exists. A prespecified outcome hierarchy or a multiplicity adjustment can help control that issue, but the registry record does not report whether either was used. The record reports zero analyses, so there are no posted estimates, standard errors, confidence intervals, or test results from which to evaluate the analysis methods or precision.
Missing-data handling can also affect interpretation, especially when outcomes are measured repeatedly. General approaches may include defining the analysis population, describing missingness, and stating how unavailable measurements are handled. The registry record does not report missing-data rules, the number of participants assessed at each secondary-outcome time point, or whether analyses used all enrolled participants or another population. These omissions limit assessment of completeness and potential bias.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists nine outcome measures. The primary outcome is technical success; secondary outcomes include clinical success, procedure success, ankle brachial index, Rutherford classification, VascuQoL, target lesion and vessel revascularization, and vessel patency. Several measures have multiple listed assessment times: baseline, 30 days, and 6 months. Repeated outcome and time-point testing raises a general multiplicity concern, because multiple statistical tests can increase the chance of at least one apparently notable result.
The registry record does not report whether a statistical testing hierarchy was specified, whether secondary analyses were exploratory, or whether a multiplicity adjustment was planned or applied. It also reports zero analyses. Consequently, there are no posted analysis estimates or test results with which to assess how outcomes were analyzed or whether multiplicity was addressed.
The record does not report the statistical analysis plan, analysis populations beyond the statement that 154 distinct lesions in 112 patients were analyzed for the primary endpoint, or rules for inclusion and exclusion. It does not report missing-data methods, the completeness of follow-up at the listed secondary-outcome times, or how repeated measures were handled. These details matter because exclusions, unavailable measurements, and different analysis populations can alter the interpretation of an estimate.
The primary endpoint is lesion-level, while adverse-event summaries are participant-level. The registry record does not report whether within-patient correlation between multiple lesions was accounted for. These reporting gaps do not establish that the methods were inadequate; they mean that the relevant methods are not reported in the registry record and cannot be evaluated from it.
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 |
|---|---|---|---|
| Interventional | 32 | 112 | 28.6% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Interventional | 3 of 112 |
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 |
|---|---|
| Interventional | 71 of 112 |
Most frequent serious adverse event terms
| Event term | Organ system | Interventional |
|---|---|---|
| Other | General disorders | 16 of 112 |
| Anemia | Blood and lymphatic system disorders | 5 of 112 |
| Infection, local | Infections and infestations | 4 of 112 |
| Target Lesion Revascularization | Vascular disorders | 4 of 112 |
| Distal Embolization | Vascular disorders | 3 of 112 |
| Amputation below the knee | Surgical and medical procedures | 2 of 112 |
| Congestive Heart Failure | Cardiac disorders | 2 of 112 |
| Infection, systemic | Infections and infestations | 2 of 112 |
| Non-Target Vessel Revascularization | Vascular disorders | 2 of 112 |
| Target Vessel Revascularization | Vascular disorders | 1 of 112 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Interventional |
|---|---|---|
| Other | Vascular disorders | 71 of 112 |
Serious events with the highest arm-level rate: other (14.3%), anemia (4.5%), infection, local (3.6%), target lesion revascularization (3.6%), distal embolization (2.7%).
The intervention group lists 112 participants at risk, 32 affected by serious adverse events, 71 affected by other adverse events, and 3 deaths. These are group-level counts in the registry record. They describe the number of affected participants as recorded, not the number of individual event episodes. The record does not provide further detail in these figures about timing, severity grading, relatedness assessment, or whether participants could appear in more than one category.
The listed serious-event terms and percentages are Other at 14.3%, Anemia at 4.5%, Infection, local at 3.6%, Target Lesion Revascularization at 3.6%, Distal Embolization at 2.7%, and Amputation below the knee at 1.8%. The term Other is a reported category; its meaning is not further described in the registry record. The listed terms should not be summed, because the record does not establish that categories are mutually exclusive.
With no control group, these figures do not show whether event frequency was higher or lower than it would have been under another approach. They also do not, on their own, establish that the intervention caused an event. The record does not report comparative safety estimates or additional attribution details.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed, single-group study evaluated the FreedomFlow™ orbital circumferential atherectomy system in peripheral artery disease. It defines the primary technical endpoint at the lesion level: residual diameter stenosis ≤50% without adjunctive therapy during the index procedure, usually within one hour after starting it. It also identifies 154 distinct lesions in 112 patients as the primary endpoint population.
The primary result itself is not reported in the registry record. There is no success count, estimated proportion, or confidence interval. Therefore, the record does not quantify the frequency of technical success or how precisely it was estimated. The listed study enrollment cannot be substituted for the missing endpoint result.
The single-group design supports description of outcomes recorded in the intervention group, but not a controlled estimate of a treatment difference. No like-for-like control group is reported, and no randomized comparison is available. Any observed event or procedural outcome would need to be interpreted as a result within this study group, not as evidence of comparative benefit or harm.
The primary endpoint is an immediate procedural measure, not a direct measure of longer-term patency, revascularization, symptoms, or quality of life. The registry lists some of these as secondary outcomes, but does not report their analysis results in the record. Safety counts and serious-event percentages provide a descriptive account, but the absence of a comparator and additional attribution details limits causal interpretation.
These distinctions are important: endpoint definition, population size, outcome frequency, precision, and comparative effect are separate pieces of evidence. The registry record gives the definition and population size, but does not report the primary outcome estimate or analysis details needed to assess its precision and robustness.
13. Why This Trial Matters Statistically
This study illustrates why an endpoint definition is not a substitute for an endpoint result. Technical success is defined using a clear lesion-level criterion, and the analysis population is identified as 154 distinct lesions in 112 patients. Yet without the number meeting the criterion, readers cannot estimate the observed success proportion or its precision. Reporting the denominator without the outcome numerator leaves the central quantitative question unanswered.
The difference between lesion-level and patient-level information is also statistically important. The primary endpoint counts lesions, whereas the safety summary counts participants. Because one patient may contribute multiple lesions, the effective information in the lesion count depends in part on within-patient association. A report of the analysis method would help readers understand whether that structure was addressed.
The single-group design places a boundary on inference. Descriptive outcomes can characterize what was recorded among treated participants, but they do not provide a concurrent counterfactual. The safety figures likewise describe the intervention group and do not establish comparative risk. Statistical precision, even when available, cannot remove this design limitation.
Finally, the registry lists multiple outcome measures and assessment times, while reporting zero analyses. This makes transparency about analysis plans, missing data, and multiplicity especially relevant. The record’s planning illustrations use hypothetical two-arm assumptions and are not the study’s own design justification or observed power. Taken together, these features show why statistical interpretation depends on the endpoint result, analysis method, and design context—not on enrollment size or endpoint wording alone.
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 principal limitation of the available registry information is the absence of the primary technical-success result. Although the endpoint is defined and the population is stated as 154 distinct lesions in 112 patients, the number of successful lesions and an estimate of uncertainty are not reported in the registry record. This prevents quantitative interpretation of the primary outcome.
The study has no reported control group and is registered as a single-group study, with allocation listed as NA and masking listed as none. It therefore cannot yield a randomized, like-for-like treatment comparison. The registry record also does not report how the endpoint was assessed or adjudicated, or whether assessors were masked.
The lesion-level endpoint includes more lesions than patients, but the record does not report whether analyses accounted for correlation among lesions from the same patient. It also does not report the statistical analysis plan, the protocol’s sample-size justification, analysis-population rules, or missing-data methods. The registry lists secondary outcomes at several assessment times, but does not report their results or the completeness of follow-up at those times.
Safety interpretation is limited to the listed group counts and serious-event terms. The registry record does not provide comparative estimates or further information about event timing and attribution in the registry record. These limitations concern what can be assessed from the registry record; they do not establish what may have been measured or analyzed outside it.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Evaluation of the FreedomFlow™ Orbital Atherectomy System to Treat Peripheral Artery Disease — NCT03635190.
- Registry record last updated 2022-11-04; status last verified 2022-07.
- Results first posted 2022-11-04.
- 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
NCT03635190 is a completed single-group evaluation of the Cardio Flow FreedomFlow™ Orbital Circumferential Atherectomy System for peripheral artery disease. The registry lists an enrollment of 112, no masking, allocation as NA, and phase as NA. The study started on 2018-12-17 and reached primary completion on 2021-03-24.
The primary endpoint is technical success per lesion, defined as residual diameter stenosis ≤50% without adjunctive therapy during the index procedure. The primary population is 154 distinct lesions in 112 patients. The registry record does not report the primary endpoint result or its uncertainty. It lists nine outcome measures and reports zero analyses. The safety summary lists 32 participants with serious adverse events, 71 with other adverse events, and 3 deaths among 112 at risk in the intervention group.