Multicenter, Nonrandomized, Prospective Study of Pulmonary Embolism Removal With the AngioJet 6F Ultra System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Multicenter, Nonrandomized, Prospective Study of Pulmonary Embolism Removal With the AngioJet 6F Ultra System (NCT01638468), a na phase 4 study. The primary outcome is Change in Right Ventricular (RV) to Left Ventricular (LV) Ratio at 24 - 48 Hours as Measured by Echocardiography.

2. Clinical Question

This setup is a before-and-after question: it concerns whether the measured ratio changed after the device procedure among enrolled participants. Such a within-group comparison is distinct from asking whether the intervention caused a change relative to what would have happened without it. With no control group, changes over time cannot be separated from other influences using this design alone. The registry record does not report a comparison with usual care or another intervention.

3. Trial Design

This was a prospective, multicenter, nonrandomized study listed as Phase 4. It used a single-group model, with allocation recorded as not applicable and masking listed as none. The registry record identifies Boston Scientific Corporation as the sponsor and lists the AngioJet Ultra PE Thrombectomy System as the device intervention. The stated purpose was to evaluate safety, efficacy, adverse events, and new information arising from use of the system in the described pulmonary embolism population.

Enrollment was 7. The study start is recorded as 2013-01 and primary completion as 2016-01. Its status is terminated. The reason for termination and whether termination affected follow-up or the planned endpoint assessment are not reported in the registry record. The record also does not state whether enrollment reached a planned target, or whether the study stopped for a safety, operational, or other reason.

Because there was one treatment group and no random allocation, the design can describe outcomes observed after treatment but cannot provide a randomized estimate of comparative treatment effects. The absence of masking also means the study was not blinded according to the registry listing. The record does not report additional safeguards against bias in assessment beyond stating that an independent core laboratory would assess the primary endpoint.

The listed secondary outcomes include technical success, all-cause death, cardiac-cause death, pulmonary and systemic systolic arterial blood pressure measures and their changes, and change in heart rate. The record lists 11 outcome measures but reports zero analyses. It does not provide a complete account of how those outcomes were assessed or analyzed. In particular, the registry record does not report a statistical analysis plan, a sample-size justification, or details of any interim analyses.

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

Analysis population for the primary outcome, as defined in the registry: Analysis was intention to treat; all participants in the study were to undergo clinical follow up to provide the information needed for this 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.

6. Primary Endpoint

The registry lists the primary outcome as Change in Right Ventricular (RV) to Left Ventricular (LV) Ratio at 24 - 48 Hours as Measured by Echocardiography, measured over Baseline to 24-48 hours.

The primary endpoint is the change in the subannular end-diastolic right-ventricular to left-ventricular ratio measured by echocardiography, from baseline to 24-48 hours after thrombectomy. The ratio compares measurements of the right and left ventricles; the registry identifies the unit as a ratio and the planned summary parameter as a mean with standard deviation. An independent core laboratory was to assess the measurements. The registry record describes echocardiography as using ultrasound waves to assess heart activity.

In general, a ratio expresses one measurement relative to another. A change in this ratio can describe whether the relative measured dimensions of the ventricles differ between the baseline and follow-up assessments. This makes it a physiological imaging measure rather than a direct count of clinical events such as death. The reason for selecting this endpoint as primary beyond its stated focus on ventricular measurements is not reported in the registry record.

The registry record does not report the baseline or follow-up means, the mean change, a standard deviation for the change, a confidence interval, or a statistical test. Therefore, it does not provide a numerical estimate of the endpoint or its precision. The endpoint description explains what was intended to be measured, but it does not establish what change was observed in the enrolled participants.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a continuous primary endpoint summarized by a mean and standard deviation. It does not report the numerical endpoint results or an analysis. The following statistical explanations are general descriptions of the methods and concepts relevant to this kind of outcome, not a claim that the registry record documents their use.

What does a mean change represent?

For a continuous measure assessed at baseline and follow-up, a within-participant change is the follow-up measurement compared with that participant’s baseline measurement. A mean change summarizes those participant-level changes across the analyzed group. The standard deviation describes how much individual changes vary around their mean. A mean and standard deviation answer different questions: the mean describes the average change, while the standard deviation describes variation among observations. Neither is reported for this endpoint in the registry record.

Analyzing participant-level changes can account for the fact that baseline and follow-up measurements belong to the same participants. A separate comparison of group means at each time point would not, by itself, show the distribution of within-participant changes. The endpoint description specifies a change from baseline, but the registry record does not report the exact statistical model or calculation used to estimate it.

What would a confidence interval add?

In general, a confidence interval gives a range of values compatible with the data and the assumptions of the statistical method. It helps communicate the precision of an estimate, rather than only its central value. A narrow interval generally indicates greater precision than a wide interval, although precision is not the same as clinical importance. No confidence interval for the primary endpoint is reported in the registry record. Without an estimate and interval, readers cannot judge how compatible the observed data might be with changes of different sizes.

A p-value, if reported, would address how surprising data at least as incompatible with a specified null hypothesis would be under that hypothesis and the model assumptions. It would not measure the probability that the null hypothesis is true, nor would it establish clinical importance. The registry record reports no primary endpoint p-value or analysis. The statistical plan, including any hypothesis test, is not reported in the registry record.

Why does the single-group design matter?

In general, repeated measurements in one group can describe how a measure changes over time in those participants. They do not establish how the same participants would have changed over that period without the intervention. Changes may reflect the intervention, the course of illness, other care, measurement variation, or other influences. Random allocation to a concurrent comparator can help balance known and unknown factors between groups; this study is listed as nonrandomized and single-group, with no comparator arm. The record therefore does not support a randomized between-group estimate.

The endpoint was to be assessed by an independent core laboratory. In general, independent assessment can help separate measurement from the treating team, but it does not eliminate every possible source of bias. The registry record does not report the laboratory’s measurement procedures, reproducibility checks, assessor masking, or how image quality and unavailable measurements were handled. Masking for the study is listed as none.

How should the planning illustrations be understood?

In general, sample-size planning calculations depend on assumptions about the effect to detect, variability, significance level, allocation, and analysis method. The registry record does not report the study’s own sample-size justification. Any planning illustrations associated with this record are not evidence that the study enrolled enough participants to meet a target, and they are not observed power. The stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect set as a stated fraction of the observed effect. The record’s study design itself is single-group, so those illustrative two-arm assumptions should not be mistaken for the actual design.

In general, an illustration based on the observed effect is conditional on that effect estimate and the chosen assumptions. It does not show the probability that the study’s result is correct. Small or unstable observed effects can lead to highly assumption-dependent planning results. The registry record does not report the detailed effect estimate or the study-specific planning rationale needed to evaluate such assumptions as part of the original design.

What can be said about event data?

For adverse events, descriptive counts indicate how many participants in the listed group were at risk and how many were affected in the recorded categories. These counts do not provide a comparative risk estimate without a control group. In general, event definitions, observation periods, and whether multiple events in one participant are counted separately matter when interpreting safety summaries. The registry record does not report all such details. The listed serious adverse event terms and percentages should therefore be read as registry descriptions, not as estimates from a controlled comparison.

Over-dispersion is a general statistical concern when count data vary more than a simple model assumes. It can make model-based uncertainty too small if the model does not allow for the extra variation. The registry record does not report a count model, an over-dispersion assessment, or an analysis of event counts, so this is a general consideration rather than a reported feature of the study analysis.

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.

R code and output

arm <- c("AngioJet Ultra PE Thrombectomy System")
n   <- c(7)
m   <- c(-0.61)
sp  <- c(0.125)
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  AngioJet Ultra PE Thrombectomy System  7  -0.610  0.125  -0.726  -0.494

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 11 outcome measures, including the primary echocardiographic endpoint and secondary clinical and physiological outcomes. When multiple outcomes are assessed, there is a general risk that some results may appear noteworthy by chance, especially if many hypothesis tests are performed. Statistical plans may address this with a prespecified outcome hierarchy or a multiplicity adjustment. The registry record does not report whether any such approach was planned or used, and it reports zero analyses.

The primary endpoint description states that the analysis was intention to treat and that all participants were to undergo clinical follow-up to provide information for the endpoint. This describes the intended analysis population and follow-up expectation, but the registry record does not report how many participants had evaluable baseline and follow-up echocardiograms. It also does not report how missing measurements, withdrawals, or incomplete follow-up were handled. The terminated status makes completeness important to assess, but the reason for termination and its effect on follow-up are not reported.

In general, intention-to-treat analysis retains participants in their assigned group regardless of treatment received, which is most directly applicable when there is randomized group assignment. This study is listed as single-group and nonrandomized. The record’s stated intention-to-treat description does not explain how that principle was applied in practice, whether every enrolled participant was included in each analysis, or how unavailable outcome measurements were treated.

The registry record does not report interim analyses, imputation methods, sensitivity analyses, or a prespecified statistical analysis plan. These absences mean readers cannot determine from the record how missing data or multiple outcomes were addressed. They do not establish that no such procedures occurred; the relevant details are simply not reported in the registry record.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pulmonary embolism, re-occurring (28.6%), death (14.3%), bowel obstruction (14.3%), macrohematuria (presence of blood cells in urine) (14.3%).

The safety listing reports a group of 7 participants at risk for serious adverse events, with 4 affected. For other adverse events, it reports 7 participants at risk, with 1 affected. These are descriptive entries for the study group. Because there is no comparator group, they do not show how these figures compare with another treatment or with no intervention.

The listed serious adverse event terms include Pulmonary Embolism, Re-occurring at 28.6%, Death at 14.3%, Bowel Obstruction at 14.3%, and Macrohematuria (presence of blood cells in urine) at 14.3%. These percentages are recorded as serious-event terms; the registry record does not provide further detail on event timing, recurrence within participants, attribution, or how the terms relate to the number of affected participants. The death count field is not reported in the registry record. The listed Death term therefore should not be treated as a complete account of the study’s death outcome or its cause.

In general, adverse-event summaries describe events observed and recorded under a study’s definitions and follow-up procedures. They do not, by themselves, establish that an intervention caused an event. The small enrolled group also limits how precisely these observations describe safety beyond the participants in this study. The registry record does not report a comparative safety analysis or uncertainty intervals for the listed figures.

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

The record establishes that a prospective, multicenter, single-group study was conducted to evaluate the AngioJet Ultra PE Thrombectomy System in participants with pulmonary embolism. Its primary endpoint was intended to measure change in the echocardiographic right-ventricular to left-ventricular ratio from baseline to 24-48 hours. It also records safety-event information and lists several secondary outcomes.

What the record does not establish is the size or direction of the primary endpoint change. It reports no endpoint estimate, confidence interval, or primary analysis. It also reports zero analyses, so the listed outcomes cannot be treated as analyzed findings on the basis of this record. The safety entries describe events in the enrolled group but do not provide a control comparison or establish causation.

In general, an observed before-and-after change is not the same as a treatment effect relative to a comparator. Without a concurrent control group, changes may reflect influences other than the intervention. The nonrandomized, single-group design is therefore central to interpretation; it limits causal comparisons even if outcome estimates were available.

The registry record reports enrollment of 7 and a terminated status. It does not report the reason for termination, whether all intended assessments were completed, or how missing data were handled. The record also does not report a study-specific sample-size justification or statistical analysis plan. These omissions prevent readers from assessing the planned analysis and the completeness of the reported results.

Accordingly, the registry record documents a study question, device, design, intended endpoint, and selected safety entries. It does not provide enough posted outcome analysis to conclude how the primary endpoint changed or to quantify a comparative effect. The study description and event listing should not be interpreted as proof for or against clinical benefit or harm.

14. Why This Trial Matters Statistically

This study illustrates a distinction that matters in clinical research: a clear endpoint description is not the same as a reported result. The registry identifies an echocardiographic measure, the baseline-to-follow-up interval, and an intended mean-based summary. Yet the record reports no analysis of that endpoint. Readers can understand what the investigators intended to assess, but cannot evaluate the estimated change or its precision from the posted record.

The single-group design also shows why a before-and-after endpoint needs careful interpretation. Within-participant measurements can describe how a physiological measure changes over time. Without a concurrent comparator, the design cannot show whether that change differs from what would have occurred without the intervention. This distinction is important when the question is about treatment effects rather than description of the treated group.

The small enrollment and listed safety events highlight the limits of descriptive safety data. Counts from a small group can identify events that occurred during the study, but they provide limited information about how frequently such events would occur in a broader population. A comparator and transparent event definitions would be needed for stronger comparative interpretation; the registry record does not report those elements in sufficient detail.

Finally, the record lists multiple outcomes but no analyses, and it does not report the analysis plan, missing-data methods, or reason for termination. These are not minor technical details: they affect how readers assess selectivity, completeness, and uncertainty. The study therefore offers a useful case for reading registry information in layers—design, endpoint specification, posted analysis, and limits on inference—without treating a planned measurement as an observed result.

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 direct limitation is that no primary endpoint result or analysis is reported in the registry record. Baseline and follow-up values, the mean change, its standard deviation, and any confidence interval or test are not reported. Although the endpoint was to be assessed by an independent core laboratory, the record does not provide measurement procedures or indicate whether assessment was masked.

The study had no comparator group and no random allocation. This prevents a like-for-like estimate of the intervention’s effect relative to another condition and leaves before-and-after changes open to alternative explanations. The registry lists no masking, and does not report other design procedures intended to reduce bias.

Enrollment was 7, and the status is terminated. The reason for termination, whether all intended participants completed follow-up, and whether endpoint data were available for all enrolled participants are not reported in the registry record. Missing-data handling and sensitivity analyses are also not reported. These omissions make it difficult to assess the completeness and robustness of any endpoint assessment.

The registry lists 11 outcome measures and zero analyses. It does not report a statistical analysis plan, multiplicity approach, study-specific sample-size justification, or interim-analysis details. The serious adverse event listing gives selected terms and percentages, but event definitions, timing, attribution, and the relationship between event terms and affected participants are not fully reported. A death count is not reported in the registry record. Together, these limitations constrain interpretation of both the intended efficacy endpoint and the descriptive safety information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Multicenter, Nonrandomized, Prospective Study of Pulmonary Embolism Removal With the AngioJet 6F Ultra System — NCT01638468.
• Registry record last updated 2018-12-05; status last verified 2018-11.
• Results first posted 2016-11-01.
• 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 NCT01638468, a Phase 4, prospective, multicenter, nonrandomized, single-group study of the AngioJet Ultra PE Thrombectomy System for pulmonary embolism. Enrollment was 7. The recorded study start is 2013-01, primary completion is 2016-01, and status is terminated. The reason for termination is not reported in the registry record.

The primary endpoint was change in the subannular end-diastolic right-ventricular to left-ventricular ratio by echocardiography from baseline to 24-48 hours after thrombectomy, with an intended mean and standard deviation summary and independent core laboratory assessment. The record lists 11 outcome measures but reports zero analyses. No primary endpoint estimate or analysis is reported.

The safety listing records serious adverse events in 4 of 7 participants at risk and other adverse events in 1 of 7 participants at risk. The record includes serious-event terms and percentages but does not report a death count. It does not provide a comparator group, a study-specific sample-size justification, or the statistical analysis plan.