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 Transcatheter Aortic Valve Replacement (TAVR) Low Risk Bicuspid Study (NCT03635424), a na na study. The primary outcome is Safety: Percent of Participants With All-Cause Mortality or Disabling Stroke Rate at 30 Days Post-procedure..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03635424 |
| Phase | NA |
| Condition | Bicuspid Aortic Valve |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 150 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medtronic Cardiovascular |
| Results posted | Yes |
2. Clinical Question
Population
People with severe aortic stenosis and bicuspid aortic anatomy who were considered at low predicted risk of mortality with surgical aortic valve replacement. The primary endpoint population is identified as the Attempted Implant Set. The record does not report further eligibility details or a description of who was included in that analysis population.
Intervention
Medtronic TAVR Systems, described as Medtronic Evolut PRO and Evolut R systems. The stated objective is to evaluate procedural safety and efficacy in this population. The record lists a single study group and does not describe a separate intervention group.
Comparator
There is no concurrent comparator group in the registry record. Surgical aortic valve replacement appears as the risk reference in the population description, not as a treatment arm in this study. Outcomes therefore cannot be interpreted as a randomized comparison between TAVR and surgery.
Primary question
What was the rate of all-cause mortality or disabling stroke by 30 days after the procedure in the Attempted Implant Set? The registry identifies this as a combined safety endpoint and specifies that it is expressed as a Kaplan–Meier rate. The endpoint result itself is not reported in the registry record.
The study is registered as NCT03635424 and has a single-group model. Recorded enrollment is 150. The listed intervention is a device, and the study objective covers procedural safety and efficacy. Those aims describe what the study set out to evaluate; they are not evidence that a particular outcome occurred or that the device produced a particular effect.
The primary question is about the frequency and timing of a serious combined outcome after an attempted implant. Combining mortality and disabling stroke focuses the endpoint on events with substantial clinical importance, while the specified follow-up period makes the question time-bounded. A combined endpoint, however, does not by itself show how often each component occurred. Separate component results would be needed to distinguish the contribution of all-cause mortality from that of disabling stroke.
Because no separate control group is listed, the study can describe outcomes in the treated group but cannot, on its own, estimate a comparative difference against surgery or another treatment. The primary endpoint result and its uncertainty are not reported in the registry record, so the clinical question is clear but its answer cannot be read from the posted results.
3. Trial Design
The registry describes a single-group device study of Medtronic TAVR Systems in people with severe bicuspid aortic valve stenosis who were at low predicted risk for mortality with surgical aortic valve replacement. The intervention description names the Evolut PRO and Evolut R systems. Recorded enrollment is 150. The record lists no comparator arm and identifies allocation as not applicable.
The study is not presented as a randomized comparison. Its single-group structure means the principal interpretation is descriptive: outcomes are observed among participants treated in the study. Without a concurrent control group, any observed event rate cannot isolate the treatment effect from other explanations, such as the participants’ underlying risk, changes over time, or differences in care. These are general limitations of single-group designs, not findings about this study’s participants.
The primary endpoint is the rate of all-cause mortality or disabling stroke at 30 days after the procedure, measured in the Attempted Implant Set. The registry describes the outcome as a Kaplan–Meier rate. The listed secondary outcomes include all-cause mortality, all stroke, permanent pacemaker implantation, myocardial infarction, life-threatening bleeding, prosthetic valve endocarditis, prosthetic valve thrombosis, and valve-related dysfunction requiring a repeat procedure. Several listed outcomes specify assessment at 30 days; the registry’s secondary-outcome list also includes all-cause mortality and all stroke without a timeframe in their titles.
The masking field is NONE. The registry lists the study status as active, not recruiting, a start date of 2018-10-30, and a primary completion date of 2019-11-13. These record fields describe the registered study timeline and status; they do not supply an endpoint result. The phase is recorded as NA.
The registry record does not report a detailed statistical analysis plan, eligibility criteria beyond the stated population, an explanation of the enrollment target, or details about interim analyses. It lists 20 outcome measures and 0 analyses. The absence of a posted analysis estimate means the planned endpoint and reported safety counts should not be mistaken for a complete analysis of the study’s primary question.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Medtronic TAVR Systems |
|---|---|
| STARTED | 150 |
| COMPLETED | 147 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Medtronic TAVR Systems |
|---|---|
| Adverse Event | 1 |
| Death | 1 |
| Device not implanted | 1 |
Analysis population for the primary outcome, as defined in the registry: Attempted Implant Set
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.
| Characteristic | Unit | Medtronic TAVR Systems |
|---|---|---|
| Participants analysed | 150 | |
| Age, Continuous | Years of age | 70.3 (SD 5.5) |
| Sex: Female, Male: Female | Participants | 72 |
| Sex: Female, Male: Male | Participants | 78 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | Participants | 150 |
| Body Surface Area (BSA) | m^2 | 1.9 (SD 0.2) |
| Society of Thoracic Surgeons (STS) Score | % risk of mortality | 1.4 (SD 0.6) |
| New York Heart Association (NYHA) Classification: NYHA Class I | Participants | 3 |
| New York Heart Association (NYHA) Classification: NYHA Class II | Participants | 106 |
| New York Heart Association (NYHA) Classification: NYHA Class III | Participants | 40 |
| New York Heart Association (NYHA) Classification: NYHA Class IV | Participants | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Safety: Percent of Participants With All-Cause Mortality or Disabling Stroke Rate at 30 Days Post-procedure., measured over 30 days.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percent of participants (K-M rate) |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint combines all-cause mortality and disabling stroke occurring by 30 days after the procedure. It is defined for the Attempted Implant Set and expressed as a percent of participants using a Kaplan–Meier rate. The endpoint is intended to capture serious outcomes relevant to procedural safety during a specified follow-up period.
A composite endpoint counts the occurrence of any listed component as an endpoint event. This can provide a single summary of a set of important outcomes, but it also combines events that may differ in frequency, severity, or clinical meaning. The composite rate alone would not reveal how much each component contributed. Separate results for mortality and disabling stroke would be needed to understand the component pattern; such primary component results are not reported in the registry record.
In general, a Kaplan–Meier estimate accounts for the timing of events and for participants whose event status is not observed through the full follow-up period. It relies on assumptions about censoring and the follow-up information available. The registry identifies the endpoint as a Kaplan–Meier rate, but does not report the estimate, its confidence interval, the number of endpoint events, or details of follow-up and censoring.
The endpoint therefore defines a clinically focused question, but its definition is not itself a result. Without the reported rate and a measure of uncertainty, the registry record does not show the observed frequency or precision of the primary outcome.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted registry information identifies a single-group study and describes its primary safety endpoint, but does not report a primary endpoint estimate. In particular, no 30-day Kaplan–Meier rate, confidence interval, or count of participants with the combined outcome is reported in the registry record. This prevents an assessment of the observed frequency of all-cause mortality or disabling stroke in the Attempted Implant Set and of the precision of that estimate.
The adverse-event record reports 1 death in the Medtronic TAVR Systems group. The timing and relationship of that death to the primary endpoint are not reported in the registry record. It therefore should not be treated as the primary endpoint event count or used to infer the primary endpoint rate. The record separately lists 57 participants at risk for serious adverse events and 57 affected, as well as 150 at risk for other adverse events and 120 affected. These are adverse-event summaries, not a substitute for the defined primary endpoint result.
In general, a point estimate describes the observed event rate, while a confidence interval communicates uncertainty around that estimate. A narrow interval would indicate greater precision under the analysis assumptions; a wide interval would indicate less precision. Here, the primary estimate and interval are not reported, so neither the event rate nor its statistical precision can be evaluated from the registry record.
The single-group design also limits what any event rate could establish. A rate in treated participants would describe outcomes observed in this group, but it would not provide a randomized comparison with surgical aortic valve replacement or another treatment. The registry describes low predicted surgical risk as a population characteristic; it does not make surgery a control arm. Differences between this study population and a separate population could reflect differences in eligibility, baseline risk, follow-up, outcome definitions, or other factors.
The listed adverse-event percentages for serious terms describe reported terms, but the registry record does not clarify their denominator or whether participants could contribute more than one term. They should not be read as a complete measure of overall safety or as a comparison with another treatment. The posted material lists secondary outcomes, but does not provide analysis estimates for those outcomes.
A planning illustration based on an observed effect is not a report of observed power and cannot fill the gap left by a missing endpoint estimate. The registry record does not provide the results needed to determine whether the primary question was answered with adequate precision. As a result, interpretation should remain limited to the study structure, endpoint definition, and adverse-event counts that are actually reported.
9. Statistical Methods Explained
What does a single-group design estimate?
In general, a single-group study estimates outcomes within the group receiving the study intervention. It does not directly estimate the difference between that group and a concurrent control. A comparison with a separate group, a historical rate, or an external benchmark requires additional assumptions because groups may differ in participant characteristics, care, outcome definitions, or follow-up. The registry record lists a single-group model and no comparator arm, so it does not support a randomized treatment contrast.
The record identifies allocation as not applicable and masking as NONE. Those fields describe the registered design; they do not supply a statistical adjustment strategy. Details about covariate adjustment, handling of baseline risk, or analyses intended to address confounding are not reported in the registry record.
What does the Kaplan–Meier rate represent?
In general, the Kaplan–Meier method estimates the probability of remaining free of an event over time while accounting for follow-up that ends before an event is observed. Participants may be censored when their later event status is unknown, and the method uses the time they were observed. Its interpretation depends on the follow-up information and on assumptions about censoring. The primary endpoint is explicitly described as a Kaplan–Meier rate at 30 days, but the registry record does not give the estimate, confidence interval, event count, censoring details, or a fuller description of the analysis.
The endpoint combines all-cause mortality and disabling stroke. In general, a composite endpoint is counted when any component occurs. This can yield a single measure for a set of important events, but it can hide differences between components. A reader would need component-specific estimates and event counts to determine which component contributed most. The registry does not report those primary endpoint details.
What does a confidence interval add?
In general, a confidence interval expresses the uncertainty associated with an estimated rate under the statistical model. It helps distinguish a precise estimate from one compatible with a broad range of values. It does not remove biases from study design, and it does not make a single-group study comparative. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be assessed.
What should be inferred from the planning illustration?
The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. It states that the effect to detect is a fraction of the observed effect. For time-to-event outcomes, the illustration is described as giving total events; for other outcomes, it is described as participants per arm. The actual illustration values are not reported in the registry record.
In general, a sample-size calculation explores how much information a future design might need under specified assumptions. It is not the observed study result, and a calculation based on an observed effect is not observed power. The equal-allocation, two-arm assumptions in this illustration do not describe the registered single-group study. The record does not report the trial’s own sample-size justification or establish that this planning illustration was part of the trial design.
How should adverse-event counts be interpreted?
The adverse-event record gives participants at risk and affected for serious and other adverse events. In general, counts of affected participants are different from counts of event occurrences: one participant may experience more than one event, and an event-term list may include overlapping reports. The registry record does not explain whether the displayed term percentages use participants or events as their denominator, nor does it provide enough information to infer overlap among terms. These safety summaries should be read as descriptive counts and reported terms, not as adjusted estimates or comparative treatment effects.
What analyses are not described?
The registry lists 20 outcome measures and 0 analyses. A detailed statistical analysis plan, inferential tests, adjustment methods, missing-data procedures, and interim analyses are not reported in the registry record. This means it is not possible to determine from the posted record how such matters were prespecified or handled. No particular statistical test or adjustment should be assumed.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 20 outcome measures, including a primary endpoint and multiple secondary outcomes. When a study examines many outcomes, the chance of observing at least one apparently unusual result can increase if each is tested separately. In general, multiplicity methods can control or describe this issue, but the appropriate approach depends on the study’s goals and analysis plan. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or adjustment of significance levels.
The record lists 0 analyses and does not provide a statistical analysis plan. It therefore does not report which outcomes were analyzed, which inferential procedures were used, or how any estimates were selected for presentation. The endpoint list alone does not establish that all outcomes were measured or analyzed as planned.
Missing-data details are also not reported in the registry record. For the primary Kaplan–Meier endpoint, the available follow-up and censoring pattern would matter to interpretation. The registry does not report the number of participants with incomplete follow-up, reasons for missingness, or any sensitivity analysis. It is therefore not possible to assess whether missing observations could affect the estimated rate.
The Attempted Implant Set is named as the primary endpoint population, but its membership and analysis rules are not described. Details on how participants were classified, how attempted implants were defined, or how deviations from the planned intervention were handled are not reported in the registry record. Other analysis populations are not specified.
These omissions do not establish that such procedures were absent from the conduct of the study; they mean that they cannot be evaluated from the registry record. The posted information does not support claims about adjustment for multiple testing, missing-data imputation, or a particular analysis population beyond the label given for the primary endpoint.
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 |
|---|---|---|---|
| Medtronic TAVR Systems | 57 | 150 | 38.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Medtronic TAVR Systems | 1 of 150 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Medtronic TAVR Systems | 120 of 150 |
Most frequent serious adverse event terms
| Event term | Organ system | Medtronic TAVR Systems |
|---|---|---|
| Atrioventricular Block Complete | Cardiac disorders | 13 of 150 |
| Hypotension | Vascular disorders | 7 of 150 |
| Bundle Branch Block Left | Cardiac disorders | 5 of 150 |
| Atrial Fibrillation | Cardiac disorders | 4 of 150 |
| Device Leakage | Product Issues | 4 of 150 |
| Atrioventricular Block | Cardiac disorders | 2 of 150 |
| Atrioventricular Block Second Degree | Cardiac disorders | 2 of 150 |
| Bradycardia | Cardiac disorders | 2 of 150 |
| Cardiac Failure Congestive | Cardiac disorders | 2 of 150 |
| Gastrointestinal Hemorrhage | Gastrointestinal disorders | 2 of 150 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Medtronic TAVR Systems |
|---|---|---|
| Bundle Branch Block Left | Cardiac disorders | 51 of 150 |
| Atrioventricular Block First Degree | Cardiac disorders | 18 of 150 |
| Thrombocytopenia | Blood and lymphatic system disorders | 13 of 150 |
| Hypertension | Vascular disorders | 11 of 150 |
| Anemia | Blood and lymphatic system disorders | 10 of 150 |
| Bundle Branch Block Right | Cardiac disorders | 9 of 150 |
| Anemia Postoperative | Injury, poisoning and procedural complications | 8 of 150 |
Serious events with the highest arm-level rate: atrioventricular block complete (8.7%), hypotension (4.7%), bundle branch block left (3.3%), atrial fibrillation (2.7%), device leakage (2.7%).
The adverse-event summary lists 57 participants at risk for serious adverse events and 57 affected in the Medtronic TAVR Systems group. For other adverse events, it lists 150 at risk and 120 affected. These are descriptive counts in the registry record. They do not by themselves establish severity beyond the serious-event classification, causality, or a comparison with another treatment.
The most frequently listed serious-event terms include Atrioventricular Block Complete at 8.7%, Hypotension at 4.7%, Bundle Branch Block Left at 3.3%, Atrial Fibrillation at 2.7%, Device Leakage at 2.7%, and Atrioventricular Block at 1.3%. The denominator and counting rules for these percentages are not reported in the registry record. The terms may not represent mutually exclusive participants, and the percentages should not be added or interpreted as an overall event rate.
The adverse-event record lists 1 death. The timing, cause, and relationship to the intervention are not reported in the registry record. This count cannot be assumed to be the number of primary endpoint events, which is defined as all-cause mortality or disabling stroke by 30 days in the Attempted Implant Set.
Without a concurrent control group and fuller event definitions, follow-up details, and denominators, these figures are best read as reported safety summaries rather than comparative evidence.
12. What the Result Does, and Does Not, Mean
The registry record establishes that this was a single-group study of Medtronic TAVR Systems in people with severe bicuspid aortic stenosis at low predicted risk for surgical aortic valve replacement. It specifies a primary endpoint of all-cause mortality or disabling stroke by 30 days, measured as a Kaplan–Meier rate in the Attempted Implant Set. It also reports adverse-event counts and selected serious-event terms.
The record does not report the primary endpoint estimate, its confidence interval, or the number of primary endpoint events. It therefore does not show the observed 30-day rate or how precisely that rate was estimated. Nor does the listed death count establish the primary endpoint result: the registry does not report its timing or whether it meets the endpoint definition and analysis-population criteria.
Even if a rate were available, a single-group result would describe outcomes in the treated group rather than a causal difference between TAVR and surgery. The study has no listed surgical control arm. Low predicted risk with surgical aortic valve replacement is part of the population description, not evidence from a randomized comparison. A comparison with outcomes in another population would require careful consideration of differences in eligibility, risk, follow-up, and outcome ascertainment.
The record’s adverse-event counts are not a complete comparative safety analysis. Their interpretation is constrained by missing denominator and event-counting details, and by the absence of a concurrent comparator. The list of secondary outcomes identifies additional questions of interest, but analysis estimates for those outcomes are not reported.
Accordingly, the registry information describes the question, design, and some reported safety information, but it does not establish the primary endpoint rate or a comparative treatment effect. It should not be interpreted as showing that TAVR does or does not improve outcomes, or as establishing the absence or presence of a particular risk relative to surgery.
13. Why This Trial Matters Statistically
This study raises a statistical question that is important for interpreting evidence in a population described by a specific valve anatomy and surgical risk: what outcomes were observed after the procedure, and how precisely were they estimated? The endpoint is defined as all-cause mortality or disabling stroke by 30 days, and the record specifies a Kaplan–Meier rate. Clear endpoint definitions and time horizons are essential for understanding what an estimate would represent.
The single-group design makes the distinction between description and comparison especially important. A within-group event rate may be useful for describing observed outcomes, but it cannot by itself establish how those outcomes compare with what would have occurred under another treatment. This matters when a population characteristic refers to surgical risk: that reference does not turn surgery into a control arm.
The record also illustrates why endpoint estimates need measures of uncertainty and transparent analysis details. A point estimate without an interval can be difficult to interpret; in this case, neither is reported for the primary endpoint. The absence of reported analysis details about missing follow-up, multiplicity, and the analysis population further limits independent assessment.
Finally, adverse-event summaries answer different questions from the primary endpoint. Counts of affected participants and percentages for event terms can help describe reported safety observations, but they do not replace the prespecified endpoint result or create a comparison group. The value of the registry record is therefore in clarifying the study objective and design, while its missing outcome estimates limit what can be concluded statistically.
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 main limitation for interpreting this trial from the registry record is that the primary endpoint result is not reported. There is no posted Kaplan–Meier rate, confidence interval, endpoint event count, or component-specific primary outcome result. The registry record therefore does not permit assessment of the frequency or precision of the primary safety outcome.
The study is listed as single-group, with no concurrent comparator. Outcomes observed among treated participants cannot be interpreted as a randomized treatment contrast with surgical aortic valve replacement. The registry record does not report an external comparison strategy or adjustment intended to support a causal comparison.
Several details needed to interpret the event summaries are also absent. The record does not report the denominator and counting rules behind the serious-event term percentages, the timing and relationship of the listed death, or details about follow-up and censoring for the primary endpoint. The definition and membership of the Attempted Implant Set are not described beyond its name as the primary endpoint population.
The registry lists 20 outcome measures and 0 analyses, but does not report a statistical analysis plan, multiplicity procedures, missing-data handling, interim analyses, or a sample-size justification. The planning illustration described in the record is based on an observed effect and hypothetical equal allocation between two arms; it is not a substitute for the trial’s own design rationale and does not match the registered single-group structure.
The record status is active, not recruiting, and a primary completion date is listed as 2019-11-13. These fields do not supply results or explain the status history. These limitations concern the information available in the registry record and do not establish what analyses may exist elsewhere.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Medtronic Transcatheter Aortic Valve Replacement (TAVR) Low Risk Bicuspid Study — NCT03635424.
- Registry record last updated 2026-05-05; status last verified 2026-04.
- Results first posted 2020-12-21.
- 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
NCT03635424 is a Medtronic Cardiovascular single-group device study of Medtronic TAVR Systems in people with severe bicuspid aortic valve stenosis at low predicted risk for surgical aortic valve replacement. The intervention description names the Evolut PRO and Evolut R systems. Recorded enrollment is 150.
The primary endpoint is all-cause mortality or disabling stroke by 30 days, expressed as a Kaplan–Meier rate in the Attempted Implant Set. The record lists secondary outcomes including mortality, stroke, pacemaker implantation, myocardial infarction, bleeding, prosthetic valve complications, and repeat procedure. It lists 20 outcome measures and 0 analyses.
The registry record reports adverse-event counts and selected serious-event terms, but does not report the primary endpoint estimate or its uncertainty. The study is listed as active, not recruiting, with a start date of 2018-10-30 and primary completion date of 2019-11-13. A concurrent comparator and detailed analysis plan are not reported.