NHLBI DIR LAMPOON Study: Intentional Laceration of the Anterior Mitral Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Implantation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for NHLBI DIR LAMPOON Study: Intentional Laceration of the Anterior Mitral Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Implantation (NCT03015194), a na na study. The primary outcome is Number of Participants With "Acceptable" Technical Success of the LAMPOON Procedure.

2. Clinical Question

3. Trial Design

This was a completed, single-group interventional study sponsored by the National Heart, Lung, and Blood Institute. The registry lists phase as not applicable, allocation as not applicable, and masking as none. Enrollment was 32. With no randomized allocation or comparator group, the design describes outcomes after LAMPOON and transcatheter mitral valve replacement; it does not estimate a comparative treatment effect.

The registry gives a start date of 2017-06-20 and a primary completion date of 2018-07-26, and lists the study status as completed. The brief summary describes screening through medical history, examination, and medical-record review. Before the procedure, participants were to have blood tests, an ECG, a heart CT scan, and an echocardiogram. The summary describes anesthesia or moderate sedation, inpatient recovery, repeat testing before hospital discharge and at later follow-up visits, and yearly follow-up phone calls for about 5 years.

The procedure combined LAMPOON with transcatheter mitral valve replacement. The registry’s arm description specifies leaflet traversal, laceration, and immediate valve replacement, guided by fluoroscopy with transesophageal echocardiography or intracardiac echocardiography. The study’s stated purpose was to test safety and effectiveness, but the registry does not report a control condition against which either could be compared.

Enrollment should not be confused with the adverse-event group size: the registry separately records 30 participants at risk in both the serious and other adverse-event categories. The relationship between those figures and the primary endpoint analysis is not reported in the registry record. The analysis population and the handling of participants without endpoint data are also not reported.

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 Number of Participants With "Acceptable" Technical Success of the LAMPOON Procedure, measured over Exit from the Cardiac Catheterization Laboratory.

The primary endpoint counts participants meeting an explicitly defined standard of acceptable technical success at exit from the cardiac catheterization laboratory. It is a composite, conjunctive definition: all listed conditions must be met for a participant to count as a success. It combines technical steps, a physiologic threshold, procedural safety, device delivery and positioning, and freedom from specified emergency procedures or reintervention.

The physiologic component is a peak LVOT gradient < 50 mm Hg. The endpoint also requires successful traversal and laceration of the anterior mitral leaflet, absence of procedural mortality, successful access, delivery, and retrieval of the LAMPOON device system, and successful deployment and correct positioning of the first intended device. A participant must also be free from emergency surgery or reintervention related to the device or access procedure.

As a technical endpoint, this measure focuses on whether the intended procedure and device implantation were completed under the registry’s defined conditions. It does not, by itself, describe longer-term outcomes or establish how the procedure compares with another approach. The registry notes that the first two factors are modifications of the MVARC consensus endpoint specific to LAMPOON. The number of participants who met the full definition is not reported in the registry record, so the endpoint’s observed success rate cannot be described from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group study and a binary primary outcome reported as a number of participants. The endpoint is binary at the participant level because each person either meets the complete definition of acceptable technical success or does not. Reporting a count is a direct way to describe the number meeting a criterion, but a count alone does not show how uncertain an underlying success proportion may be. The primary outcome count is not reported in the registry record, and no interval estimate or test result is reported for it.

What does a confidence interval communicate?

General statistical explanation: a confidence interval gives a range of values compatible with the data under a specified method. For a participant proportion, an interval would communicate precision as well as the estimated proportion. A narrow interval indicates greater precision under that method; a wide interval indicates more uncertainty. The interval does not correct for bias in how participants were selected, outcome data were collected, or the endpoint was defined. Since the registry does not report the primary success count or an interval, precision for this endpoint cannot be evaluated from the record.

Why does the single-group design matter?

General statistical explanation: a single-group outcome can describe what occurred among enrolled participants, but it does not provide the concurrent comparison needed to estimate a contrast between treatment strategies. A comparison requires outcomes under each strategy, with a design and analysis that support a fair contrast. Here, the registry lists a single-group model and no allocation. Therefore an observed outcome, even if reported, would not alone establish what would have occurred to similar participants under a different procedure. This is a limitation of the design, not a calculation that can be repaired by applying a significance test to the single group.

How should the composite endpoint be understood?

General statistical explanation: a composite endpoint combines multiple conditions into one outcome. In this study, all listed criteria are required for the participant to count as an acceptable technical success. This approach summarizes several aspects of the procedure in a single measure, but the count does not show which criterion most often prevented success. Component-level counts and results are not reported in the primary endpoint entry. The definition also includes a procedure-specific modification of the MVARC consensus endpoint, so the precise criteria matter when interpreting or comparing results.

What do the sample-size illustrations represent?

The sample-size assumptions describe planning illustrations based on the observed effect, not the trial’s own design. They assume a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. This is a hypothetical planning framework, not a description of the actual single-group study, which has no two-arm allocation in the registry. Such figures are not observed power and do not establish that the study was adequately powered. The trial’s own sample-size justification is not reported in the registry record. No additional sample-size assumptions or protocol rationale should be inferred.

What can be said about statistical testing?

General statistical explanation: a p-value assesses how compatible data are with a specified null model, given the assumptions of the test. It does not measure the size or clinical importance of an effect, and it does not make a nonrandomized or uncontrolled comparison causal. The registry records zero analyses, and it does not report a p-value for the primary endpoint. Thus, no formal hypothesis-test result can be interpreted from the record. The absence of a reported test is not evidence that a particular statistical result was obtained.

Over-dispersion is a general concern when count data vary more than a model assumes. In a binary endpoint, appropriate uncertainty estimation depends on the design, the denominator, and the distributional assumptions. The record does not report a fitted model or a count-based analysis for the primary endpoint. It would therefore be inappropriate to claim that over-dispersion was assessed or to assign a model to the study. The endpoint is a participant count, not a time-to-event outcome in the information reported.

Interpretation of any analysis also depends on who was included, how missing outcome observations were handled, and whether outcomes were assessed consistently. The registry record does not report the analysis population, missing-data method, or detailed statistical plan. These omissions limit assessment of analytic robustness independently of the missing primary result.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and zero analyses. It provides the definition and timeframe for the primary technical-success endpoint, but the other outcome measure’s details are not reported in the registry record. The record does not describe a hierarchy of endpoints, a family of confirmatory hypotheses, or an adjustment for multiple testing. It is therefore not possible to determine whether multiplicity was addressed in a protocol or analysis plan.

Missing-data handling is not reported in the registry record. The primary endpoint entry does not give the observed number meeting the definition, the number with evaluable endpoint data, or an account of participants whose endpoint status could not be determined. Enrollment of 32 cannot be treated as the endpoint denominator without a reported analysis population. The adverse-event group size of 30 is reported separately and should not be assumed to be the denominator for the primary endpoint.

The registry does not report an intention-to-treat, per-protocol, or other analysis population, nor does it describe imputation, sensitivity analyses, or reasons for missing observations. Interim analyses and stopping rules are not reported in the registry record. These are reporting gaps, not evidence that a particular method was or was not used outside the registry entry. Without this information, readers cannot assess whether the endpoint analysis included all enrolled participants or how incomplete follow-up might affect the reported results.

11. 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: anemia (33.3%), heart failure (30.0%), hypotension (30.0%), cardiac arrest (23.3%), acute kidney injury (16.7%).

The registry reports that 30 participants were at risk and 30 were affected in the serious adverse-event category; it gives the same figures for other adverse events. These are registry summary counts, and they do not explain the number of events per participant or the observation period. The listed serious-event terms include anemia at 33.3%, heart failure at 30.0%, hypotension at 30.0%, cardiac arrest at 23.3%, acute kidney injury at 16.7%, and cardiogenic shock at 16.7%.

The record also reports 16 deaths in the group. The adverse-event summary does not state the timing or causes of these deaths, nor does it establish whether they were related to the procedure or devices. It does not provide event-level details or a breakdown of recurrence. The percentages should therefore be read as the registry’s reported summaries, not converted into additional counts or interpreted as comparative risks.

These safety entries are distinct from the primary technical-success endpoint, which is assessed at exit from the cardiac catheterization laboratory and includes absence of procedural mortality. The death total and the primary endpoint are not interchangeable measures. The registry does not report enough detail to connect the death count to the procedural-mortality criterion or to determine the timing of deaths across follow-up.

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

The record’s main statistical contribution is its specification of a procedure-specific technical endpoint and its description of a single-group study of LAMPOON with transcatheter mitral valve replacement. The endpoint combines successful leaflet treatment and device implantation with a physiologic threshold and safeguards against specified procedural complications. It gives readers a defined target for evaluating technical success, rather than relying on an unspecified impression of procedural completion.

However, the registry does not report the number of participants who met the primary endpoint. It therefore does not establish the observed technical-success result or its precision. The enrollment figure is not a substitute for that result. The available adverse-event summaries provide selected safety information, but they do not fill the primary-endpoint reporting gap.

The single-group design also limits interpretation. This study can describe outcomes within the enrolled group if those results are reported, but it cannot establish a difference relative to another strategy. The design does not support a randomized causal comparison, and no comparator is listed in the registry. The registry’s background describes concern about obstruction with usual TMVR techniques and the rationale for studying LAMPOON; that rationale is not evidence of a comparative benefit.

The listed follow-up schedule indicates that later assessments were part of the study plan, but the primary endpoint is measured at catheterization-laboratory exit. The registry entry does not report longitudinal results that would establish later clinical outcomes. In addition, the adverse-event summary does not provide timing or causal attribution for the events or deaths. The evidence described in this record is consequently limited to the design, endpoint definition, and reported safety summaries, rather than a complete account of effectiveness or longer-term outcomes.

13. Why This Trial Matters Statistically

This study is statistically notable for using a defined technical-success endpoint tailored to a procedure intended to address a specific procedural concern. The criteria make clear that success involves more than completing leaflet laceration: it also includes the gradient threshold, device-system handling, correct deployment and positioning, and freedom from specified emergency procedures or reintervention. Such detail helps readers understand what the endpoint is intended to capture.

The single-group structure is equally important. It is suited to describing experience in participants receiving the procedure, but it cannot supply a direct estimate of the difference between LAMPOON and an alternative. Recognizing this distinction prevents descriptive outcomes from being read as comparative evidence. The registry lists no allocation and no control arm, so any claim about relative performance would require evidence beyond the design.

Reporting completeness matters as much as endpoint definition. The registry does not report the primary endpoint result, its uncertainty, the analysis population, or missing-data methods. As a result, readers cannot assess either the observed frequency of acceptable technical success or its precision. The safety summary adds context but lacks event timing and causal attribution, and should not be used to infer the primary result.

Finally, planning assumptions should be distinguished from actual study design. The sample-size assumptions describe hypothetical two-arm planning illustrations, while the registry describes a single-group study. Treating those illustrations as observed power or as proof of the study’s design would confuse planning calculations with collected evidence. This trial demonstrates why statistical interpretation depends on aligning the endpoint, design, analysis, and completeness of reporting.

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 principal limitation for interpreting the primary outcome is that its observed result is not reported in the registry record. Although the endpoint definition and assessment time are specified, the number of participants meeting the definition, the denominator used, and an estimate of uncertainty are absent. Enrollment of 32 does not resolve those omissions.

The study has no comparator group in the registry design. Accordingly, outcomes cannot be contrasted with a concurrent control, and the design does not estimate a comparative effect. The enrollment and adverse-event counts should not be treated as if they came from a randomized comparison. The registry also does not state the sample-size justification for the actual study.

The safety summary is limited to group-level figures and selected event terms. It reports 30 participants at risk and affected for both serious and other adverse events, and 16 deaths, but does not report the timing, causes, or causal relationship of deaths in that summary. It also does not provide event-level detail or explain how these figures relate to the endpoint analysis population.

Additional analytic details are absent: the registry does not report an analysis population, missing-data handling, endpoint adjudication procedures, multiplicity methods, or interim analyses. The record describes planned follow-up, but does not report later outcome results in the primary endpoint entry. These limits mean that the information available supports description of the intended design and recorded summaries, but not a complete assessment of endpoint performance, precision, or longer-term outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: NHLBI DIR LAMPOON Study: Intentional Laceration of the Anterior Mitral Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Implantation — NCT03015194.
• Registry record last updated 2023-08-15; status last verified 2023-03.
• Results first posted 2021-04-29.
• 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.

18. Record Summary

NCT03015194 is a completed, single-group study sponsored by the National Heart, Lung, and Blood Institute. The registry lists enrollment of 32, allocation as not applicable, masking as none, and phase as not applicable. It describes LAMPOON followed by transcatheter mitral valve replacement in adults recommended for the procedure.

The primary outcome is the number of participants meeting the registry’s acceptable technical-success definition at exit from the cardiac catheterization laboratory. The observed number is not reported in the registry record. The adverse-event summary lists 30 participants at risk and affected in both serious and other adverse-event categories, along with 16 deaths and selected serious-event terms with percentages.

The single-group design does not provide a randomized comparator. The registry does not report the primary endpoint estimate, its precision, the analysis population, or missing-data methods. The study dates are 2017-06-20 for start and 2018-07-26 for primary completion; status is completed.