Bare Metal Bifurcation Stent Clinical Trial in Humans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bare Metal Bifurcation Stent Clinical Trial in Humans (NCT00607321), a na na study. The primary outcome is Number of Participants With Target Vessel Failure (TVF) at 30 Days Post Procedure..

2. Clinical Question

The stated purpose was to assess feasibility and safety for the device in a specific coronary anatomy. The primary endpoint combines several clinically distinct events into one participant-level outcome. That structure can capture more than one type of unfavorable event within a single summary, while also making the component definitions and their attribution rules important to interpretation.

The question is therefore descriptive for a treated group: what did the registry record report about device use and the defined outcomes? Without a comparator, the study cannot provide a randomized estimate of how outcomes differ from another treatment or from no device. The record identifies 60 enrolled participants, but does not report the primary endpoint count, the number assessed at 30 days, or a participant flow accounting for the endpoint population.

3. Trial Design

The registry identifies this as a completed, single-group clinical trial with an enrollment of 60. Its intervention is the Medtronic Bifurcation Stent System. The stated study purpose was to assess feasibility and safety for treatment of single de novo bifurcation lesions in native coronary arteries with specified reference-vessel dimensions. The record lists coronary artery disease and myocardial ischemia as conditions.

The trial start is recorded as 2008-02 and primary completion as 2010-08. The status is COMPLETED. The phase is listed as NA. Allocation is also listed as NA, and masking is listed as NONE. The record describes a SINGLE GROUP model, and no comparator arm is described. Its skip note states that this is not a randomized comparison and that arms are not a like-for-like control comparison; in the described design, there is one study group rather than a comparative treatment arm.

These design details determine what the outcomes can support. A single-group study can describe observed outcomes among participants in that group, but it does not provide a concurrent comparison for separating device-associated outcomes from differences that could arise from participant characteristics, clinical setting, or other factors. The registry record does not describe random assignment, blinding, a control treatment, or a statistical plan that would support a causal comparison.

The primary outcome is the number of participants with TVF at 30 days after the procedure. Secondary outcomes listed are device success and numbers of participants with target vessel failure at 6 months, 9 months, and 12 months. The record lists five outcome measures overall, but it does not provide results for those measures in the registry record for this analysis. It also reports zero analyses. The details of outcome assessment procedures, follow-up completeness, and analysis populations are not reported in the registry record.

The listed sponsor is Medtronic Vascular. The registry record gives the enrollment and dates, but these registry entries alone do not show whether the enrolled participants represent a wider population or how many participants contributed data at each follow-up time. Those questions require information about eligibility, recruitment, follow-up, and outcome denominators that is 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

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 Number of Participants With Target Vessel Failure (TVF) at 30 Days Post Procedure., measured over 30 days.

The primary endpoint counts participants with target vessel failure (TVF) at 30 days after the procedure. The registry definition classifies TVF as occurring if any of several events occurred: recurrent myocardial infarction in the target territory when it was not clearly attributed to a vessel other than the target lesion; cardiac death when it was not clearly due to a non-target vessel endpoint; or clinically driven target revascularization.

This is a composite endpoint: different event types contribute to a single outcome. In general, composites can provide a broad summary of clinically important events, but interpretation depends on the definition of each component, the attribution rules, and the frequency of each component. A participant meeting more than one component is still counted as a participant with the endpoint when the measure is expressed as a number of participants. The registry record does not report component-level counts, so the relative contribution of myocardial infarction, cardiac death, and target revascularization cannot be assessed from the available record.

The 30-day timeframe defines the period for the primary outcome. It is distinct from the secondary follow-up outcomes listed at 6 months, 9 months, and 12 months. The endpoint is suited to describing whether participants experienced one of the specified events during that period, but its interpretation depends on knowing the number assessed and the number meeting the definition. Neither the primary event count nor its analysis is reported in the registry record. Accordingly, the registry description establishes what was intended to be counted, not the observed frequency or precision of that outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary measure as a number of participants with an event. This is a binary participant-level outcome: each participant either meets the stated TVF definition during the 30-day timeframe or does not, assuming endpoint status can be determined. The record does not report the number classified in either category or how unresolved endpoint status was handled. As a result, the outcome definition can be discussed, but no observed event proportion or uncertainty estimate can be interpreted.

What does a participant-level count represent?

A count records how many participants meet a defined condition. If the goal is to describe the frequency of an event in a study group, the count is usually interpreted together with the number of participants assessed. The enrollment of 60 is not automatically the endpoint denominator: some participants might not have an assessment, and the record does not report endpoint completion or an analysis population. A proportion also requires both a numerator and a denominator. Neither should be reconstructed when those details are absent.

The endpoint is a composite, meaning that several event types can satisfy the same primary outcome. In general, this can offer a single summary spanning multiple clinically relevant events, but the summary does not reveal which component occurred unless component results are reported separately. A composite can also be influenced more by components that occur more often. The registry record gives the component definitions, including rules for attributing events to the target vessel, but it does not report separate component counts. Therefore, no component-specific frequency or contribution can be described.

Why does the single-group design matter?

The record identifies a single-group model and does not describe a comparator. A descriptive estimate in one group answers how often an outcome was recorded among the participants analyzed, provided the numerator and denominator are known. A treatment comparison asks a different question: how outcomes differ between groups under a specified design and analysis. Without a comparator, the trial record cannot directly estimate a between-group difference. The absence of a randomized comparison also means that participant or setting differences cannot be handled as randomized balance between treatment groups.

Masking is listed as NONE. In general, masking can reduce the influence of knowledge about treatment assignment on assessment or reporting, depending on the outcome and how it is measured. The record does not provide further detail on outcome adjudication or assessor procedures. It is not possible to infer whether any independent review occurred or how potential assessment bias was addressed.

What can confidence intervals and tests tell readers?

In general, a confidence interval expresses statistical uncertainty around an estimate under the assumptions of the method used. It is not a guarantee that the true value lies within its limits, and its width reflects both the information in the data and the model. A hypothesis test addresses compatibility of data with a specified null hypothesis under a statistical model; a p-value is not the probability that the null hypothesis is true. Such summaries are meaningful only when the estimate, analysis population, and method are identified.

No confidence interval, p-value, or primary analysis result is reported in the registry record, and the record lists zero analyses. There is therefore no reported test or interval to interpret. General statistical principles do not fill that gap. The number of enrolled participants alone does not reveal the endpoint estimate, its precision, or whether any formal comparison was conducted.

How should sample-size illustrations be read?

In general, sample-size calculations are planning exercises that describe the amount of information a study might need under specified assumptions. They are not observed outcomes and do not establish what the study found. The planning assumptions described for the illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect stated as a fraction of an observed effect. Those assumptions describe a two-arm planning framework, while this trial is identified as single-group. They should not be read as the trial's own design or as evidence of observed power.

The registry record does not report a trial-specific sample-size justification or the assumptions used when setting enrollment. The stated enrollment of 60 is not, by itself, proof that the trial had adequate precision for the primary endpoint. A defensible assessment would require the intended target effect, anticipated event frequency, chosen error rates, and planned analysis. These details are not reported in the registry record. Any planning illustration is conditional on its assumptions and cannot substitute for an observed effect estimate or its uncertainty.

Why do follow-up and event definitions matter?

TVF is defined over 30 days, while secondary target vessel failure outcomes are listed at 6 months, 9 months, and 12 months. In general, changing the follow-up window changes the period during which events can be counted. Outcome definitions and time windows must therefore accompany estimates. The record does not report follow-up completeness or how events outside a participant's observed follow-up were handled. It also does not provide the timing of safety events or details about adjudication.

The stated TVF definition contains attribution qualifications: a recurrent myocardial infarction is included when it is not clearly attributed to a vessel other than the target lesion, and cardiac death is included when it is not clearly due to a non-target vessel endpoint. These rules are part of the endpoint and can affect classification. The registry record does not describe how attribution decisions were made, whether reviewers were independent, or how uncertainty in attribution was resolved. Those methods are not reported in the registry record.

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("Subjects Receiving Bifurcation Stents")
n      <- c(52)
events <- c(2)
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  Subjects Receiving Bifurcation Stents  52  2  3.8  0.5  13.2  1.1  13.0  1.2  13.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and secondary outcomes that include device success and target vessel failure at 6 months, 9 months, and 12 months. It also reports five outcome measures overall and zero analyses. The record does not describe a statistical analysis plan, a hierarchy among secondary outcomes, or any adjustment for multiple testing. It is therefore not possible to determine whether multiplicity was considered or how multiple outcome claims would have been interpreted.

In general, examining several outcomes or timepoints can increase the chance of at least one apparently notable result when each is tested separately. A prespecified hierarchy or an adjustment procedure can address some multiplicity concerns, but the suitable approach depends on the study question and analysis plan. No such procedure is reported in the registry record. No inferential results are reported for which multiplicity adjustments could be evaluated.

Missing data and analysis populations are also not described. The enrollment is 60, but the record does not state how many participants had evaluable 30-day outcomes, how many were assessed at each later timepoint, or how missing follow-up was handled. It does not define an intention-to-treat, per-protocol, or other analysis population. These details are needed to understand the denominator for each result and whether exclusions or missing assessments could affect interpretation.

In general, missing outcome data can influence an estimate when the probability of missingness is related to outcome status or participant characteristics. The impact depends on the amount and pattern of missingness and the analysis assumptions. Since those details are not reported in the registry record, the direction or size of any potential influence cannot be assessed. The available record supports describing the planned outcome framework, but not reconstructing the analysis population or making claims about completeness.

12. Safety Results

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

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: angina pectoris (13.3%), chest pain (8.3%), myocardial infarction (6.7%), anaemia (3.3%), non-cardiac chest pain (3.3%).

The safety information records 23 participants affected by serious adverse events among 60 at risk. It separately records 46 participants affected by other adverse events among 60 at risk. These are participant counts in the safety record. They do not indicate the number of distinct event episodes, and the record does not state whether participants could be counted in both categories.

The listed serious adverse event terms and percentages are angina pectoris, 13.3%; chest pain, 8.3%; myocardial infarction, 6.7%; anaemia, 3.3%; non-cardiac chest pain, 3.3%; and acute myocardial infarction, 1.7%. The registry record does not specify the denominator or counting convention for these term-level percentages, or whether a participant could contribute to more than one term. These percentages should therefore be read as recorded labels, not added together or converted into a participant total.

The safety group is titled “1. Branch Bifurcation Stent System,” while the intervention name is Medtronic Bifurcation Stent System. The record does not report whether adverse events were considered related to the device, nor does it provide event timing or further details for individual events. Deaths are not reported in the registry record. Serious adverse event counts describe safety observations; without attribution and comparative data, they do not establish causation or a relative safety effect.

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

The registry record documents a completed, single-group study with an enrollment of 60 and a primary outcome definition focused on TVF at 30 days. It also lists later target vessel failure timepoints and device success as secondary outcomes. The safety record reports 23 participants affected by serious adverse events and 46 affected by other adverse events, each among 60 at risk. These are the available numerical outcome details in the record.

The primary endpoint result itself is not reported in the registry record. Neither the count of participants with TVF nor an endpoint denominator, estimate, confidence interval, or p-value is available. As a consequence, the recorded details do not establish the observed frequency or precision of the primary outcome. The secondary outcome results are likewise not reported in the registry record.

The study design is not a randomized comparison. A single-group description cannot establish how outcomes would have differed under another treatment or no device, and it cannot by itself establish that the device caused an observed event or prevented one. Even if the primary event count were available, it would describe outcomes in the analyzed study group rather than provide a randomized estimate of a comparative effect.

The safety counts should also be interpreted descriptively. The record does not state whether adverse events were attributed to the device, how events were assessed, or how many participants had events in both categories. The term-level percentages are reported, but their denominators and counting rules are not. Accordingly, they should not be treated as comparable risk estimates or as evidence about relative safety.

The findings that can be stated are limited to the trial's design, stated purpose, enrollment, endpoint definitions, listed follow-up outcomes, and recorded adverse event counts. Whether the device met a feasibility or safety objective cannot be determined from these registry entries alone. That would require outcome results and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This trial illustrates why design and outcome reporting are essential to statistical interpretation. The registry describes a specific intended use: the Medtronic Bifurcation Stent System for single de novo bifurcation lesions in native coronary arteries with specified vessel dimensions. It also defines a primary 30-day composite endpoint and lists later follow-up outcomes. These details establish the question the study set out to address, but they do not supply the outcome estimates needed to answer it.

The single-group design is particularly important. Statistical analysis of a single group can describe event counts and estimate their frequency when denominators and follow-up are available. It cannot provide the same kind of evidence as a randomized comparison. The distinction is not a technicality: an observed outcome frequency in one group does not estimate the difference that would have occurred under an alternative treatment.

The primary outcome is a composite of recurrent myocardial infarction, cardiac death, and clinically driven target revascularization, with attribution conditions for some events. Such definitions make endpoint specification a core part of analysis. Without component results, readers cannot tell which kinds of events contributed to the composite. Without the total assessed at 30 days, they cannot evaluate the endpoint count as a rate or determine its precision.

The record also demonstrates the difference between describing safety observations and making causal claims. Serious adverse events and other adverse events are counted, but event attribution and participant overlap are not reported. Those counts have descriptive value while remaining distinct from a comparative safety estimate.

Finally, planning calculations do not replace results. General sample-size illustrations based on two-arm assumptions are not observed power and do not show what the study found. A useful statistical reading keeps the design, endpoint definition, observed results, and uncertainty separate. In this case, the registry records the design and outcome framework, but the primary outcome analysis and several details necessary for assessing precision are not reported.

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 main limitation for statistical interpretation is that the primary endpoint result is not reported in the registry record. The record gives the TVF definition and 30-day timeframe, but not the number of participants meeting the endpoint, the number assessed, or an estimate with uncertainty. Consequently, the primary outcome cannot be quantitatively characterized from this record.

The study is identified as single-group, with allocation NA and masking NONE; no comparator is described. This limits interpretation to descriptive outcomes in the study group and does not support a randomized estimate of a treatment difference. The record does not describe participant characteristics, detailed eligibility criteria, or the number followed at each timepoint, so generalizability and follow-up completeness cannot be evaluated.

Although secondary outcomes are listed, their results are not reported in the registry record. The record lists five outcome measures and zero analyses, and does not report a statistical analysis plan, analysis populations, missing-data procedures, or multiplicity handling. These absences prevent assessment of how endpoints were analyzed and whether the reported enrollment corresponds to the population contributing to each outcome.

The safety information reports affected-participant counts and selected serious adverse event terms, but does not report attribution to the device, event timing, term-level denominators, or participant overlap across categories. Deaths are not reported in the registry record. These gaps limit interpretation of the safety counts and prevent comparative conclusions.

The registry record describes the intended lesion dimensions and study purpose, but it does not provide enough participant-level or outcome detail to assess the precision or completeness of the findings. The limitations concern what can be concluded from this record; they do not establish that unreported analyses or procedures did not occur outside the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Bare Metal Bifurcation Stent Clinical Trial in Humans — NCT00607321.
• Registry record last updated 2017-05-18; status last verified 2017-04.
• Results first posted 2011-08-31.
• 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 describes the Medtronic Bifurcation Stent System study as completed, single-group, and enrolling 60 participants. It lists coronary artery disease and myocardial ischemia as conditions, identifies Medtronic Vascular as sponsor, and records a start of 2008-02 and primary completion of 2010-08. The study purpose was to assess feasibility and safety for single de novo bifurcation lesions in native coronary arteries with specified vessel dimensions.

The primary outcome was the number of participants with TVF at 30 days, defined using recurrent myocardial infarction, cardiac death, or clinically driven target revascularization under the stated attribution rules. Secondary outcomes included device success and TVF at 6 months, 9 months, and 12 months. The primary and secondary outcome results and their analyses are not reported in the registry record.

Safety information records 23 participants with serious adverse events and 46 with other adverse events among 60 at risk. The record does not report event attribution or deaths. The single-group design and missing endpoint results limit the statistical conclusions that can be drawn from the record.