MANTA Ultrasound Closure Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for MANTA Ultrasound Closure Study (NCT05142566), a na na study. The primary outcome is Rate of Any Large Bore Access-site Related VARC-2 Major Vascular Complication.

2. Clinical Question

The clinical question concerns both a particular closure approach and a specified safety outcome after femoral arterial access. The primary endpoint is framed as a count of participants with at least one qualifying major vascular complication, rather than as a measure of time to an event or the number of events. The endpoint description says it was adapted from VARC-2 Criteria.

Because the study had no control group, its central descriptive question is whether and how often the specified complication was recorded in the enrolled group. A single-group study cannot, on its own, separate outcomes associated with the device and closure approach from outcomes that might have occurred under another approach or in a different patient group. The registry record does not report a primary endpoint result, so the complication rate cannot be described from the posted results.

3. Trial Design

The MANTA Ultrasound Closure Study (NCT05142566) is described as a prospective, multicenter study of ultrasound-guided closure with the MANTA Vascular Closure Device. Its model is single-group, its allocation is listed as NA, and masking is listed as none. The arm description identifies an open-label, single-arm study using ultrasound guidance during device deployment. No randomized comparison is described.

The registry record lists an enrollment of 17. The study start date is 2022-08-09, and primary completion is listed as 2023-01-11. Its status is terminated. The reason for termination is not reported in the registry record. Phase is listed as NA, which does not describe a phase assignment.

The stated aim was to demonstrate the safety of ultrasound-guided MANTA VCD closure in patients undergoing elective TAVR procedures with planned percutaneous femoral arterial access. The intervention is identified as a device. The primary outcome is a count of participants with any large-bore access-site-related VARC-2 major vascular complication within 30 days. The endpoint description notes that it is adapted from VARC-2 Criteria.

The registry record lists eight outcome measures, including the primary endpoint and secondary outcomes involving hemostasis, technical success, ambulation, treatment success, procedure time, and minor vascular complications. Outcome analyses are not listed. The record therefore describes the intended study question and endpoints, but does not provide an analyzed primary endpoint result or results for the secondary outcomes. The sample-size justification, detailed statistical analysis plan, and reason for termination 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:

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 Rate of Any Large Bore Access-site Related VARC-2 Major Vascular Complication, measured over within 30 days.

The primary endpoint is the rate of any large-bore access-site-related VARC-2 major vascular complication within 30 days. Its unit is participants, and its parameter is a count of participants. In practical terms, the endpoint is intended to identify how many participants experienced at least one event meeting the adapted VARC-2 major vascular complication definition during the stated follow-up period. The exact adaptation details beyond the description are not reported in the registry record.

A participant-based endpoint focuses on whether an individual had an event, rather than counting repeated events in the same person as separate participants. This can make the outcome easier to interpret as a safety frequency in the study group. However, interpretation still depends on a clear event definition, consistent ascertainment, and an identified analysis population. The registry record names the endpoint and timeframe but does not report the observed participant count or explain further how events were adjudicated or classified.

The endpoint is relevant to the stated safety aim because it concerns major complications related to large-bore access at the closure site. Yet a count from one group would be descriptive, not a direct estimate of the difference between closure approaches. Since the primary result is not reported in the registry record, no observed rate, precision estimate, or comparison can be stated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a single-group study and lists no outcome analyses. Consequently, it does not report a statistical estimate for the primary endpoint, an uncertainty interval, or a hypothesis-test result. Statistical concepts can still clarify what an analysis of this type would ordinarily mean, but they should not be mistaken for analyses documented in this record.

What does a participant count represent?

The primary endpoint is specified as a count of participants with any qualifying complication. For a binary endpoint, each participant is classified according to whether the event occurred during the defined period. The resulting count describes the number of participants meeting the definition; a rate or proportion would additionally require a defined denominator and a reported analysis. The registry record identifies the endpoint unit and its 30-day timeframe but does not post a primary endpoint count, denominator for that analysis, or calculated rate.

A participant-level count differs from an event count. If a person has repeated events, an endpoint counting participants generally treats that person as having the outcome, rather than counting each occurrence as a separate participant. Whether repeated events were handled this way in the study analysis, and how multiple event types were classified, are not reported in the registry record. The endpoint’s full operational definition is also not given beyond the note that it was adapted from VARC-2 Criteria.

What would an uncertainty interval tell a reader?

In general, a confidence interval communicates the statistical uncertainty around an estimate, given the observed data and the method used to calculate the interval. A narrower interval indicates greater precision under that method; a wider interval indicates less precision. Intervals do not establish that an estimate is free from bias, and they do not address limitations such as selection, incomplete follow-up, or inconsistent outcome classification. No confidence interval for the primary endpoint is reported in the registry record, so there is no interval to interpret for this outcome.

For a small single-group study, a participant count may provide useful descriptive information, but the estimate of event frequency can remain imprecise. The amount of uncertainty depends on the observed result and the statistical method. Since the primary result and its analysis are absent, neither the size nor the direction of that uncertainty can be quantified from the registry record.

How does the single-group design affect inference?

A single-group study can describe outcomes among people enrolled under a particular approach. It does not directly estimate a treatment contrast against a concurrent control group. A contrast requires outcomes for groups that can be compared under a defined design and analysis. Here, allocation is listed as NA and the study model is single-group. Thus, no randomized treatment comparison or adjusted comparative effect is reported. General comparisons with other populations would be vulnerable to differences in participant mix, procedures, follow-up, and other influences.

Open-label status means masking is listed as none. This identifies that the registry does not describe masked study conduct; it does not by itself show that outcome assessment was biased. For outcomes requiring clinical judgment, knowledge of the intervention can be relevant to assessment. The record does not explain the event-review process or whether adjudication was independent, so further claims about ascertainment cannot be made.

What does the sample-size planning description mean?

The registry’s planning description specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that the effect to detect is a stated fraction of the observed effect. The description is a planning illustration and is not the trial’s own design justification. It does not establish that this single-group study enrolled participants according to those assumptions, and no sample-size justification is reported in the registry record.

Planning calculations ask how many participants might be needed under specified assumptions for a future comparison. They are not a measure of the probability that a completed study’s finding is true. In particular, a planning illustration based on an observed effect must not be described as observed power. No specific planning estimates or outcome-based sample-size calculations are reported in the registry record, and the two-arm assumptions do not convert this single-group study into a comparative trial.

Why can over-dispersion matter?

In general, over-dispersion refers to variability in count data that is greater than expected under a model’s assumptions. If present, it can make standard errors too small when a model does not account for that extra variability, producing uncertainty estimates that are too narrow. This concept is most relevant when outcomes are analyzed as counts across units or over time. The primary endpoint is described as a participant count with a binary interpretation, and no model, dispersion estimate, or statistical analysis is reported. There is therefore no basis to claim that over-dispersion was assessed or affected the study results.

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("Ultrasound Closure")
n      <- c(17)
events <- c(0)
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  Ultrasound Closure  17  0  0.0  0.0  19.5  0.0  18.4  0.1  18.5

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists eight outcome measures: a primary major vascular complication endpoint and secondary outcomes covering time to hemostasis, technical success, ambulation success, time to ambulation, treatment success, procedure time, and minor vascular complications. The record does not list outcome analyses. It also does not report a multiplicity strategy for handling the possibility of testing or interpreting several outcomes.

In general, multiplicity arises when several outcomes or hypotheses are examined. Without a prespecified approach, repeated testing can increase the chance of at least one apparently notable result arising by chance. Possible approaches include identifying a primary outcome as the main confirmatory question, adjusting testing procedures, or treating secondary outcomes as exploratory. The registry names a primary endpoint, but the analysis plan and any adjustment for multiple comparisons are not reported in the registry record. No claim about how multiplicity was handled can therefore be made.

Missing-data methods and analysis populations are also not reported in the registry record. The enrollment figure does not establish how many participants contributed to each outcome, whether follow-up was complete, or how missing measurements were treated. The record does not state whether an intention-to-treat, per-protocol, or other analysis population was used. These details matter because exclusions, incomplete follow-up, and differing denominators can affect both the interpretation and precision of an outcome estimate.

Outcome analyses are listed as none. As a result, there are no reported primary or secondary estimates to evaluate for multiplicity, missingness, or population definitions. The absence of these details should be kept distinct from a finding that data were missing or that a particular analysis approach was used; neither is established by the registry record.

12. Safety Results

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

Deaths

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: transient ischemic attack (tia) (11.8%), arrhythmia (5.9%), anemia (5.9%), systemic infection (5.9%).

The adverse-event record lists the Ultrasound Closure group with 17 participants at risk for serious adverse events and 2 affected, and 17 at risk for other adverse events and 4 affected. Deaths are listed as 0. These are reported as separate categories. The registry record does not say whether participants could appear in both categories, so the counts should not be added or treated as mutually exclusive.

The listed serious adverse event terms are Transient Ischemic Attack (TIA), 11.8%; Arrhythmia, 5.9%; Anemia, 5.9%; and Systemic Infection, 5.9%. These percentages are registry entries for event terms, not the primary endpoint result. The record does not report the corresponding event counts, whether terms overlap within participants, or how the terms were coded.

Serious adverse events and the primary endpoint are not interchangeable. The primary endpoint is specifically any large-bore access-site-related VARC-2 major vascular complication within 30 days. The adverse-event counts do not establish whether a listed event was access-site-related or met that endpoint definition. No conclusion about the primary endpoint can be drawn from these figures alone.

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

The record shows that the study was designed to assess ultrasound-guided MANTA closure in elective TAVR procedures involving planned percutaneous femoral arterial access. It specifies a 30-day primary safety endpoint based on major access-site-related vascular complications and describes the study as open label and single group. It also records serious and other adverse-event counts and a death count.

It does not report the primary endpoint result or any outcome analyses. Therefore, the record cannot establish how many participants experienced the specified major vascular complication, how precisely its frequency was estimated, or whether the study met its stated safety aim. The absence of a posted result is not equivalent to a zero event count, nor does it demonstrate that the endpoint was not assessed.

The adverse-event figures provide limited descriptive safety information. They do not identify the primary endpoint outcome, and the record does not explain whether categories overlap or whether individual adverse events were related to the device or procedure. The serious adverse event terms should be read as event labels, not as a complete account of the primary safety outcome.

The single-group design also limits what the study could show even if outcome results were available. Without a separate comparator group, observed outcomes would describe the enrolled group and could not directly establish how outcomes differ under another closure approach. The study’s status is terminated, but the reason is not reported in the registry record. Termination alone does not explain the outcome data or establish why the study ended.

Accordingly, the most defensible interpretation is that the registry documents the study question, design, endpoint definitions, and selected adverse-event counts, while leaving the primary result and analysis unavailable. It does not support a conclusion about comparative performance or a definitive estimate of the primary endpoint.

14. Why This Trial Matters Statistically

This study raises a useful statistical distinction between describing safety in a treated group and estimating a comparative effect. A single-group design can record whether specified events occurred under a particular closure approach. It cannot, without a comparator, directly quantify how those outcomes differ from another approach. That distinction remains important even when an endpoint is clinically specific and follow-up is defined.

The primary endpoint is a participant-based count of major access-site-related complications within 30 days. That framing makes the event definition and denominator central to interpretation. A reader needs to know which participants were included in the analysis, how qualifying events were assessed, and whether follow-up was complete. Those analysis details and the primary result are not reported in the registry record, illustrating how endpoint registration alone does not provide an interpretable estimate.

The adverse-event entries also show why safety summaries need careful separation from primary outcomes. Serious adverse-event counts may be relevant to overall safety description, but they do not automatically answer a narrower endpoint question based on event location, severity criteria, and timeframe. Definitions, category overlap, and attribution all affect what a count means.

Finally, a terminated study with no outcome analyses listed leaves readers without a documented answer to the registered primary question. Statistical transparency depends not only on naming outcomes, but also on reporting results, analysis populations, missing-data handling, and uncertainty. These elements allow readers to assess whether the study’s observations are precise and how far they can be generalized. Their absence limits interpretation, regardless of whether the underlying study collected the relevant information.

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 important trial-specific limitation in the registry record is the absence of outcome analyses. Although the primary endpoint and secondary outcomes are named, no primary or secondary results are listed. This prevents assessment of the endpoint frequency, its precision, and the relationship between the reported adverse-event summaries and the primary safety question.

The single-group design has no concurrent control group. Any outcomes reported for this group would be descriptive and could not directly distinguish the effects of ultrasound-guided MANTA deployment from other procedural or participant-related influences. Allocation is listed as NA, and no randomized comparison is described.

The study is listed as terminated, but the reason is not reported in the registry record. The record does not report a sample-size justification, detailed statistical analysis plan, analysis populations, missing-data methods, or how the adapted VARC-2 endpoint was operationalized beyond its brief description. It also does not explain how events were adjudicated or whether outcome assessors were independent.

The enrollment is listed as 17, but that figure does not establish how many participants contributed to each endpoint or whether all had complete follow-up. The adverse-event entries do not clarify whether participants could contribute to more than one category or how event terms were assigned. These limitations make it important not to treat the adverse-event counts as a substitute for the primary endpoint result or as a complete comparative safety assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: MANTA Ultrasound Closure Study — NCT05142566.
• Registry record last updated 2023-07-27; status last verified 2023-03.
• Results first posted 2023-07-27.
• 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.

19. Record Summary

NCT05142566, the MANTA Ultrasound Closure Study, is a prospective, multicenter, open-label, single-group device study of ultrasound-guided MANTA VCD deployment during elective TAVR procedures with planned percutaneous femoral arterial access. Enrollment is listed as 17. The study started on 2022-08-09, reached primary completion on 2023-01-11, and has a status of terminated. The reason for termination is not reported in the registry record.

The primary endpoint is any large-bore access-site-related VARC-2 major vascular complication within 30 days, measured as a count of participants. No outcome analyses are listed, and the primary endpoint result is not reported in the registry record. The adverse-event record lists 2 participants with serious adverse events, 4 with other adverse events, and 0 deaths; these entries do not establish the primary endpoint result. The record does not describe a comparator group, analysis populations, missing-data methods, or a detailed analysis plan.