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 Medtronic CoreValve REDO Study (NCT01051310), a na na study. The primary outcome is Percentage of MAE Free Subjects.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01051310 |
| Phase | NA |
| Condition | Aortic Valve Stenosis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 18 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medtronic Cardiac Rhythm and Heart Failure |
| Results posted | Yes |
2. Clinical Question
Population
Patients with a failing aortic bioprosthesis who were considered poor candidates for repeat surgical valve replacement. Eligible subjects were to be at least 75 years old and require another aortic valve replacement.
Intervention
Implantation of the Medtronic CoreValve System as a percutaneous aortic valve replacement in the failing bioprosthesis.
Comparator
There was no concurrent comparison group. The registry describes a single-group, non-randomized study; allocation is listed as NA.
Primary question
What proportion of participants were free of the composite of major adverse events at 30 days after the procedure? The study also identified technical and procedural success at discharge as a primary performance endpoint, but its result is not reported in the registry record.
The study addressed a specific clinical setting: a previously implanted aortic bioprosthesis that had failed in a patient considered at high risk for another surgical valve replacement. The proposed investigation was prospective and multicenter, and the intervention was implantation of a CoreValve device within the failing valve. The registry describes follow-up of immediate performance and safety, including assessments at discharge and 30 days, as well as annual follow-up out to 48 months post procedure.
The main safety question focused on whether participants remained free of a composite major adverse event by 30 days. The composite included cardiac and non-cardiac events, with events ranging from death and neurological events to bleeding, valve-related complications, and urgent procedures. A separate primary performance endpoint concerned technical and procedural success at discharge. These endpoints address different aspects of the study: safety events and procedural performance.
Because the study had no concurrent control group, it cannot establish how outcomes compare with another treatment or with repeat surgery. The record describes the study objectives and lists adverse-event figures, but does not report the primary endpoint result. Consequently, the registry record does not resolve the primary safety question in a way that permits a direct effect estimate.
3. Trial Design
The Medtronic CoreValve REDO Study was a prospective, multicenter, non-randomized, single-group feasibility study. The intervention was the Medtronic CoreValve System, used for percutaneous aortic valve replacement in patients with a failing previously implanted aortic bioprosthesis. The registry lists the study as completed, with enrollment of 18. Its planned population description says up to 20 patients would be included in up to four hospitals.
Eligible subjects were described as at least 75 years old, with a failing aortic bioprosthesis that could be stenotic, incompetent, or mixed. The valve types listed include homograft and stented or stentless heterograft. Participants were to be considered poor surgical candidates and to need repeat aortic valve replacement. Aortic valve stenosis is the condition listed in the record.
The study did not use random allocation or a concurrent control arm. Masking is listed as none, and phase is listed as NA. The absence of a control group means the registry’s observations describe participants who received the device, rather than a comparison between treatment strategies. Findings from a single-group feasibility study can describe observed events and procedural experience, but cannot separate intervention effects from other influences on outcomes.
The record describes immediate evaluation at discharge and 30 days, alongside subsequent annual follow-up through 48 months post procedure. The primary safety endpoint was the percentage of subjects free of a composite major adverse event at 30 days. The primary performance endpoint was technical and procedural success at discharge. Although these objectives are stated, endpoint results are not reported in the registry record.
The study start is recorded as 2008-06 and primary completion as 2010-01. The registry status is completed. The record does not report a detailed statistical analysis plan, a sample-size justification, or a description of interim analyses. Those omissions limit what can be concluded about how the planned analyses were intended to address uncertainty or evolving safety observations.
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.
Before assignment: All 18 subjects signed and informed consent and were admitted to the catheterization laboratory for an attempted implantation. All 18 subjects were subsequently implanted with the CoreValve device.
Overall Study
| Stage | Overall Study |
|---|---|
| STARTED | 18 |
| COMPLETED | 13 |
| NOT COMPLETED | 5 |
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: All enrolled subjects who received the Medtronic CoreValve aortic valve prosthesis
| Characteristic | Unit | Overall Study |
|---|---|---|
| Participants analysed | 18 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 |
| Age, Categorical: >=65 years | Participants | 18 |
| Sex: Female, Male: Female | Participants | 6 |
| Sex: Female, Male: Male | Participants | 12 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of MAE Free Subjects, measured over 30 days post-procedure.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary safety endpoint is the percentage of subjects without a composite major adverse event at 30 days post procedure. The composite includes major adverse cardiac or cerebral events and other major adverse events. The listed cardiac or cerebral events include cardiac death, specified atrioventricular block, neurological events, and surgical aortic valve replacement. Other listed events include non-cardiac death, cardiac tamponade, valve dysfunction, structural valve deterioration, cardiogenic shock, endocarditis of the operated valve, valve thrombosis, aortic dissection or perforation, major bleeding, peripheral embolic events, and emergent revascularization.
A composite endpoint can capture several clinically serious event types in a single outcome. This can be useful when a study is examining safety across multiple possible complications, especially when each individual event may be uncommon. However, the overall composite does not show whether any particular component was more influential than another. Components can also differ in severity and frequency, so a composite result requires interpretation alongside its definition and component-level information.
The endpoint is expressed as the percentage free of events, so a result would need to be interpreted as the proportion of participants who had not experienced any component event by the specified time. The registry record states the endpoint definition and timeframe but does not report the endpoint result. It also does not provide a component-level breakdown for this primary endpoint. The separate primary performance endpoint, technical and procedural success at discharge, is described but its result is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a completed, single-group feasibility study with enrollment of 18 and describes a primary safety endpoint assessed at 30 days. It does not report the percentage of subjects free of major adverse events, a confidence interval for that percentage, or a corresponding test result. The primary safety result therefore cannot be quantified from the registry record. The primary performance endpoint at discharge is also named without a reported result.
That distinction matters: an endpoint definition tells readers what the investigators intended to measure, not what was observed for that endpoint. The listed adverse-event information gives some safety context, but it does not replace the missing primary endpoint result. Nor does the record establish that the adverse-event figures correspond to the same assessment window or composite definition as the primary endpoint. The 30-day timeframe is attached to the primary endpoint; the event summary should not be assumed to share that timeframe unless the registry states so.
The adverse-event row lists 15 participants affected by serious events among 18 at risk, and 14 affected in the other event category among 18 at risk. It also lists 5 deaths. These are descriptive registry figures for the overall study group. They should be read as reported counts, not as estimates of a treatment effect. The record does not provide a control group, an adjusted comparison, or a causal analysis that would support attributing these events to the device or comparing their frequency with another strategy.
The listed serious-event terms include documented Mobitz type II AVB II, AVB III at 27.8%, bleeding event at 11.1%, neurological events at 11.1%, surgical aortic valve replacement at 11.1%, myocardial infarction at 5.6%, and non structural valve dysfunction at 5.6%. The registry record does not explain whether these terms overlap within participants, whether the percentages use all enrolled participants as their denominator, or how event timing relates to the primary endpoint. They therefore should not be summed or treated as mutually exclusive categories.
In general, a confidence interval describes the range of values compatible with the observed data under a specified statistical model and indicates the precision of an estimate. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be assessed from this record. The sample-size illustrations associated with the posted results are planning scenarios, not observed power, and do not substitute for an estimate with uncertainty. No exact endpoint effect is available in the record to support further interpretation.
9. Statistical Methods Explained
What does a single-group design estimate?
A single-group study describes outcomes among participants who received the intervention. It can document procedural experience, event occurrence, and follow-up observations in the enrolled population. Without a concurrent comparison group, however, it does not directly estimate the difference between the intervention and another treatment or a no-intervention strategy. Changes or events observed after a procedure may reflect the intervention, underlying illness, participant characteristics, or other influences. A single-group design cannot disentangle those influences in the way a suitable comparative design may be able to.
That limitation is particularly important when interpreting safety. An event recorded after treatment is a temporal observation; it is not by itself proof that the treatment caused the event. The registry describes this as a non-randomized study with no control arm, and it does not report an adjusted comparative analysis. Accordingly, the adverse-event data support description of the study group, not a causal treatment-effect conclusion.
How should a composite endpoint be understood?
A composite endpoint combines multiple event types into a shared outcome definition. In general, this can make a safety outcome more comprehensive and can capture different ways that a participant may experience a major complication. For this study, the stated composite includes cardiac or cerebral events and other major adverse events, including death, bleeding, valve complications, and urgent procedures.
Composite outcomes need careful reading because components may differ in clinical meaning, severity, and frequency. A participant who experiences any qualifying component can contribute to the composite outcome, but an overall composite result does not identify which component drove the result. Component-specific information can clarify the pattern, provided the registry defines the components and reports them with appropriate denominators and timeframes. The record describes the composite but does not report the primary endpoint result or a component-level result for that endpoint.
What would a confidence interval add?
In general, a confidence interval conveys uncertainty around an estimated quantity. A narrower interval indicates greater precision under the assumptions of the analysis; a wider interval indicates less precision. The estimate and interval are needed together: the estimate describes the observed outcome, while the interval indicates how much uncertainty remains about the underlying value. For a proportion, the choice of interval method and the available information can matter, especially in a small study or when outcomes are uncommon.
The registry record does not report a confidence interval for the primary safety endpoint. It also does not report the endpoint estimate itself. Thus the endpoint’s magnitude and precision cannot be evaluated from the registry record. General principles about confidence intervals do not fill in that missing information.
What is the role of a p-value?
In general, a p-value measures how compatible observed data are with a specified statistical null model, assuming the model and its assumptions are appropriate. It does not measure the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. A p-value is most informative when paired with an effect estimate, uncertainty interval, and a clear description of the analysis.
The registry lists no analyses, and it does not report a p-value for the primary endpoint. There is also no control group against which to make a standard treatment comparison. No inferential conclusion should therefore be inferred from the descriptive adverse-event figures alone.
What do the planning illustrations mean?
Sample-size calculations can be used to explore how many participants per arm might be needed under stated assumptions to detect a specified effect with a chosen power and significance level. Such values are planning illustrations, not observed outcomes and not evidence that a study had a particular probability of detecting an effect after it was completed. The registry’s stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and a target effect expressed as a fraction of the observed effect. The record says that time-to-event illustrations use total events, while other illustrations use participants per arm.
Those assumptions describe the planning calculations, not the actual design of this study. The trial itself is single-group and has no two-arm allocation. The registry record does not report a sample-size justification for the trial. The illustrations cannot establish that the study was adequately sized for its endpoints, and they are not observed power. No sample-size values or endpoint effect estimate are reported in the registry record, so no further quantitative interpretation is warranted.
10. Multiplicity, Missing Data and Analysis Populations
The registry record identifies two primary endpoints: a safety endpoint based on freedom from a composite major adverse event at 30 days, and a performance endpoint based on technical and procedural success at discharge. It also describes assessments at discharge, 30 days, and annual follow-up out to 48 months post procedure. When a study examines multiple endpoints, components, and timepoints, multiplicity can arise: the more questions tested, the greater the chance of finding an apparently unusual result by chance if each is assessed separately. In general, analysis plans may address this through a prespecified hierarchy, adjustment, or a clear distinction between primary and exploratory outcomes.
A multiplicity strategy is not reported in the registry record. The record also does not report an analysis plan specifying how the two primary endpoints relate to one another, whether component events were analyzed separately, or how repeated follow-up assessments were handled. No interim analyses or stopping rules are reported in the registry record.
Missing-data handling and analysis populations are also not reported in the registry record. It is therefore unclear from the record how participants without an observed outcome at a given assessment would have been handled, or which participant set would have been used for each endpoint analysis. No imputation procedure, censoring approach, or definition of an evaluable population is described. These omissions matter because incomplete follow-up can affect both the estimate and its precision, and analysis choices can influence how results are interpreted.
The primary endpoint results are not reported, so the registry record does not permit assessment of endpoint-specific denominators, missing observations, or multiplicity-adjusted inference. The listed adverse-event figures should not be treated as a substitute for those details.
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 |
|---|---|---|---|
| Overall Study | 15 | 18 | 83.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Overall Study | 5 of 18 |
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 |
|---|---|
| Overall Study | 14 of 18 |
Most frequent serious adverse event terms
| Event term | Organ system | Overall Study |
|---|---|---|
| General disorders | 12 of 18 | |
| Documented Mobitz type II AVB II, AVB III | Cardiac disorders | 5 of 18 |
| bleeding event | Injury, poisoning and procedural complications | 2 of 18 |
| Neurological events (CVA, RIND, TIA) | Nervous system disorders | 2 of 18 |
| Surgical aortic valve replacement | Surgical and medical procedures | 2 of 18 |
| Myocardial infarction | Cardiac disorders | 1 of 18 |
| non structural valve dysfunction | Product Issues | 1 of 18 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Overall Study |
|---|---|---|
| General disorders | 13 of 18 | |
| bleeding event | Injury, poisoning and procedural complications | 1 of 18 |
Serious events with the highest arm-level rate: documented mobitz type ii avb ii, avb iii (27.8%), bleeding event (11.1%), neurological events (cva, rind, tia) (11.1%), surgical aortic valve replacement (11.1%), myocardial infarction (5.6%).
The overall study row lists 18 participants at risk, 15 affected by serious events, 14 affected in the other event category, and 5 deaths. These are registry counts; they are not a comparison between treatment groups. The record does not define the label for the other event category in the information available, so its contents should not be inferred from the count.
The registry lists several serious-event terms with percentages: documented Mobitz type II AVB II, AVB III at 27.8%; bleeding event at 11.1%; neurological events (CVA, RIND, TIA) at 11.1%; surgical aortic valve replacement at 11.1%; myocardial infarction at 5.6%; and non structural valve dysfunction at 5.6%. These terms may not be mutually exclusive, and the registry record does not specify the denominator or timing for each percentage. They should not be added together or taken as separate shares of participants without that information.
The serious-event summary is distinct from the primary endpoint, which is defined as freedom from a composite major adverse event at 30 days. The record does not report the primary endpoint result or establish that the event-summary figures use the same timeframe. The reported events describe what the registry lists for this study group; they do not establish causation or allow comparison with another treatment.
12. What the Result Does, and Does Not, Mean
The record establishes that the study was completed as a prospective, multicenter, non-randomized feasibility study of the Medtronic CoreValve System in a selected population with a failing aortic bioprosthesis and high risk for repeat surgery. It records enrollment of 18 and provides descriptive adverse-event figures for the overall study group. It also defines a 30-day composite safety endpoint and a technical and procedural success endpoint at discharge.
The record does not report the primary safety endpoint result, its confidence interval, or the performance endpoint result. As a result, it does not allow readers to quantify how many participants were free of the composite event at 30 days, or how often technical and procedural success was achieved at discharge. The adverse-event counts and listed terms provide limited descriptive context, but do not answer those endpoint questions on their own.
Because the trial has no concurrent control group, its posted results cannot establish that the device caused the observed outcomes or compare outcomes against repeat surgery or another intervention. The event figures should not be treated as evidence of a relative benefit or harm. Even a complete set of descriptive outcomes would not, by itself, resolve those comparative questions.
The study’s stated follow-up objectives extend beyond the immediate period, with annual follow-up planned out to 48 months post procedure. However, the registry record does not provide the primary endpoint result or detailed long-term outcome estimates in the information available. The study objectives should therefore be distinguished from reported findings: planned assessment does not establish what was observed.
In general, results from a feasibility study can help characterize whether a procedure was undertaken and what events were recorded in the studied population. Their interpretation depends on complete outcome reporting, clear denominators, uncertainty estimates, and the design’s limitations. Here, missing primary endpoint results and the single-group design substantially constrain conclusions. The record describes the question and some safety information, but does not provide enough information to estimate a comparative treatment effect or the precision of the primary safety outcome.
13. Why This Trial Matters Statistically
This study is statistically notable for the contrast between a clearly specified clinical question and the limited endpoint results reported in the registry record. The protocol summary names both a safety endpoint and a performance endpoint, and defines the safety composite in detail. Yet the registry does not report results for either primary endpoint. That distinction is important for readers: outcome definitions are not outcome estimates, and planned follow-up is not evidence that results were reported.
The single-group design also sets a clear boundary on interpretation. Descriptive event counts can characterize the enrolled study group, but without a concurrent comparator they cannot provide a direct estimate of the difference between CoreValve implantation and another treatment strategy. This is not a matter that can be resolved by a statistical adjustment when the record does not describe a comparative group or analysis.
The record illustrates why adverse-event summaries need context. Counts and percentages are meaningful only with a clear denominator, timeframe, event definition, and understanding of whether categories overlap. The posted serious-event terms do not include enough information to establish all of these details, and should not be conflated with the separately defined 30-day primary endpoint.
Finally, the sample-size illustrations are planning scenarios rather than observed power, and the record does not report the trial’s own sample-size justification or detailed analysis plan. For statistical interpretation, the most useful additions would be the primary endpoint estimates with denominators and uncertainty intervals, clear outcome timing, and specified analysis populations and missing-data handling. Without these, the record permits a description of the study design and selected safety figures, but not a precise or comparative estimate of the primary outcomes.
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 registry record provides limited information for evaluating outcomes. Although it states that the primary safety endpoint was the percentage of subjects free of a composite major adverse event at 30 days, that result is not reported. The primary performance endpoint at discharge is also identified without a result. No confidence intervals or other uncertainty measures for either endpoint are reported in the registry record.
The study enrolled 18 participants and had no concurrent control group. Its non-randomized, single-group design limits comparative and causal interpretation. The record does not report a detailed statistical plan, analysis populations, missing-data methods, or interim analyses. It also does not explain the endpoint-specific denominators or provide a component-level result for the primary composite.
The serious-event summary includes counts and listed terms, but the record does not clarify the timeframe for those figures, whether categories overlap, or the denominator underlying each listed percentage. The meaning of the other event category in the overall row is not reported in the registry record. Consequently, the summary should be treated as descriptive rather than as a fully characterized analysis of event incidence.
The target population was selected: patients with a failing aortic bioprosthesis who were considered poor candidates for repeat surgery. Results from such a feasibility study would not automatically apply to patients with different valve conditions or surgical risk. The registry describes planned follow-up out to 48 months, but detailed long-term outcome estimates are not reported in the registry record. Together, the missing endpoint results, limited event context, and lack of a comparator constrain interpretation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Medtronic CoreValve REDO Study — NCT01051310.
- Registry record last updated 2019-01-31; status last verified 2018-08.
- Results first posted 2019-01-31.
- 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.
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18. Record Summary
The Medtronic CoreValve REDO Study evaluated percutaneous implantation of the Medtronic CoreValve System in patients with a failing previously surgically implanted aortic bioprosthesis who were considered high risk for repeat surgical valve replacement. It was a prospective, multicenter, non-randomized, single-group feasibility study, listed as completed, with enrollment of 18. The record lists the study start as 2008-06 and primary completion as 2010-01.
The stated primary safety endpoint was freedom from a composite major adverse event at 30 days post procedure. The primary performance endpoint was technical and procedural success at discharge. The record also describes annual follow-up objectives out to 48 months. It lists serious-event counts and terms for the overall study group, but does not report results for the primary safety or performance endpoints.
With no concurrent control group and no reported primary endpoint estimates or uncertainty intervals, the registry record supports a description of the study design and selected adverse-event information, not a comparative estimate of treatment effect.