A Clinical Trial to Evaluate the HeartWare MVAD® System (MVAdvantage): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Clinical Trial to Evaluate the HeartWare MVAD® System (MVAdvantage) (NCT01831544), a na na study. The primary outcome is Survival.

2. Clinical Question

This is a descriptive safety-and-performance question, not a randomized estimate of comparative treatment effect. The study planned to follow participants for 24 months, while the designated primary endpoint concerns survival at six months. The distinction matters: a longer planned observation period does not change the time point used for the primary endpoint, and it does not establish that follow-up was complete for every participant.

3. Trial Design

The registry record describes a multi-center, prospective, non-randomized, single-arm trial evaluating the HeartWare MVAD® System for advanced heart failure. The listed enrollment is 11. The intervention arm is the MVAD® Pump, described as implantation of the HeartWare MVAD® System. No separate control arm is described, and the allocation and phase fields are recorded as NA. Masking is listed as NONE.

The stated study aim was to investigate device safety and performance over 24 months. The primary endpoint is survival at six months, presented as a simple proportion. The listed secondary outcomes include survival, numbers of participants who died by six months and two years, major bleeding, device failures and malfunctions, major infection, neurological dysfunction, health-status change measured by KCCQ and EuroQol EQ-5D-5L, and functional-status change measured by the 6-minute Walk. The registry record lists 16 outcome measures in total.

The record gives a start date of 2015-07-14 and a primary completion date of 2015-09-01, and lists the study status as TERMINATED. These dates and status do not, by themselves, explain why the study ended or establish how much follow-up was completed. The reason for termination, participant disposition, and actual duration of follow-up are not reported in the registry record.

Because this is a single-arm study, the results can describe the observed experience among participants but cannot isolate the effect of the device from other factors using a concurrent randomized comparison. The registry record does not report the protocol’s detailed eligibility criteria, recruitment procedures, device-management procedures, or a statistical analysis plan. Those omissions limit what can be inferred about how the study was conducted and how its outcomes were to be analyzed.

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 Survival, measured over Six month.

The primary endpoint is survival at six months, expressed as a simple proportion of participants. In general, a survival proportion at a specified follow-up time describes the share of an analyzed group whose survival status meets the endpoint definition at that time. The registry record also specifies how certain procedures before six-month follow-up would be handled: transplants, explants for recovery, and exchanges to a device other than the MVAD® pump are eligible for endpoint analysis, with survival status identified at the time of the procedure.

Survival is a clinically important outcome in a study of advanced heart failure and an implanted support device. As a general statistical concept, a clearly defined time point helps make the endpoint interpretable and keeps the outcome tied to a specified follow-up horizon. A simple proportion is also straightforward to describe, although its interpretation depends on knowing who was included in the denominator, how missing survival status was handled, and whether follow-up was sufficiently complete.

The endpoint description does not give the number alive at six months, the denominator used in the reported analysis, or an estimate of uncertainty. The survival result and its precision are not reported in the registry record. The listed enrollment of 11 should not automatically be treated as the primary-endpoint denominator, because the record does not report the analysis population or participant-level follow-up status.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-arm design estimate?

In general, a single-arm study describes outcomes observed among participants who received the intervention. It does not include a concurrent control group against which the observed outcomes can be compared. That distinction is important for interpretation: an observed outcome can be counted and described, but the design alone cannot determine how much of that outcome is attributable to the intervention rather than to participant characteristics, other care, the course of illness, or other influences.

The registry record describes this study as prospective, non-randomized, and single-arm, with no masking. Prospective describes the intended forward collection of information; it does not by itself establish that every planned observation was collected. Non-randomized means the record does not describe randomized assignment, and the single-arm description indicates there is no like-for-like control arm in the registered design.

What does a simple survival proportion mean?

The primary endpoint is survival at six months, presented as a simple proportion. In general, a proportion is a count of participants meeting a definition divided by the number of participants included in the relevant analysis. The denominator is essential to interpretation: it should reflect the analysis population and the handling of participants whose status is unknown or whose follow-up differs from plan. The registry record does not report the survival numerator, denominator, or missing-status approach, so the proportion itself cannot be reconstructed or evaluated from the record.

The endpoint description specifies that transplants, explants for recovery, and exchanges to a device other than the MVAD® pump before six-month follow-up would be eligible for endpoint analysis, with survival status identified at the time of the procedure. This is a stated endpoint rule, not a reported outcome. The record does not provide participant-level details showing how many such procedures occurred or how they affected the analysis.

Why are confidence intervals useful?

In general, a confidence interval gives a range of values compatible with the observed data under a statistical procedure and conveys the precision of an estimate. A point estimate alone can conceal substantial uncertainty, especially when the analyzed group is small. Here, enrollment is 11, but the primary survival estimate and its confidence interval are not reported in the registry record. No uncertainty measure should be inferred from the enrollment count alone.

How should adverse-event counts be read?

The posted safety summary distinguishes participants at risk from participants affected. In the MVAD® Pump group, 11 participants were listed as at risk for serious adverse events and 7 as affected; for other adverse events, 11 were listed at risk and 10 affected. The associated percentages for selected serious terms describe participants with each listed term, as recorded. They are not counts of all event episodes, and one participant can contribute to more than one event category. The record does not provide enough detail to determine event timing, recurrence, severity grading beyond the serious-event grouping, relatedness to the device, or the exact analysis rules used for each term.

What does over-dispersion mean in general?

For count outcomes, a basic statistical model may assume that the variability is tied to the average count. Over-dispersion means the observed variability is greater than that assumption allows. In general, ignoring over-dispersion can make uncertainty look smaller than it is, while using a model that accommodates extra variability can produce more appropriate uncertainty estimates. The registry record does not report a count-model analysis or event-rate results for the outcomes, so this general concept should not be read as a claim about the analysis used in this study.

How should the listed study status affect interpretation?

The registry record lists the study as TERMINATED and gives a primary completion date of 2015-09-01. These entries describe registry status and timing; they do not explain the reason for termination, confirm completion of the planned 24-month follow-up, or show that all analyses were performed. The reason, participant disposition, and follow-up completeness 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("MVAD® Pump")
n      <- c(11)
events <- c(10)
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  MVAD® Pump  11  10  90.9  58.7  99.8  62.3  98.4  61.5  97.9

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 16 outcome measures, including the six-month survival primary endpoint and multiple safety, survival, health-status, and functional-status outcomes. It reports 0 analyses. The statistical plan for handling multiple outcomes, including any hierarchy, adjustment, or designation of confirmatory versus exploratory analyses, is not reported in the registry record.

In general, multiplicity arises when many outcomes or statistical tests are considered: the chance of at least one apparently notable finding can increase when results are interpreted without a prespecified strategy. This general concern does not establish that any particular result in this study is false or that a particular correction was required. Since the registry record does not report the analysis plan or analysis results for these outcomes, it is not possible to assess how multiplicity was addressed.

Missing-data procedures are also not reported in the registry record. The primary endpoint description gives a rule for identifying survival status at the time of certain procedures before six-month follow-up, but it does not describe how unknown survival status, incomplete follow-up, or other missing observations were handled. The record does not give the number of participants with available outcome data at each follow-up time.

The analysis populations are not reported in the registry record. Although enrollment is listed as 11, the record does not state whether every enrolled participant was included in each endpoint analysis or whether the primary endpoint denominator differed from enrollment. It also does not provide participant disposition or reasons for any exclusion. These gaps limit assessment of the representativeness and completeness of the posted results.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: major bleeding (63.6%), hemolysis (36.4%), cardiac arrhythmia (27.3%), device malfunction/failure (27.3%), major infection (27.3%).

The registry record lists 11 participants at risk for serious adverse events, with 7 affected, and 11 at risk for other adverse events, with 10 affected. These are participant counts. They do not indicate the total number of event episodes, and participants may have experienced more than one event or event type.

The listed serious-event terms and percentages are Major Bleeding, 63.6%; Hemolysis, 36.4%; Cardiac Arrhythmia, 27.3%; Device Malfunction/Failure, 27.3%; Major Infection, 27.3%; and Pericardial Fluid Collection, 18.2%. They describe the registry’s posted summaries, not a comparison with another group. Because the study is single-arm, these figures cannot establish whether the device increased or decreased risk relative to an alternative.

In general, adverse-event summaries are interpreted in light of the number of participants observed, follow-up duration, event definitions, event ascertainment, and whether events were judged related to treatment. The registry record does not report the detailed methods for those aspects, nor does it provide event timing or recurrence information in the listed summary. The percentages should therefore be read as descriptive figures for the recorded group, not as precise estimates of risk in a wider population or evidence of causation.

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

The registry record describes a prospective study of the HeartWare MVAD® System in people with advanced heart failure and sets out six-month survival as the primary endpoint. It also records adverse-event summaries among participants in the MVAD® Pump group. Those details establish what the study was intended to investigate and provide limited descriptive safety information.

The record does not report the primary survival result. It therefore does not show how many participants were alive at six months, what proportion met the endpoint, or how precise that estimate was. The listed enrollment of 11 is not a substitute for the missing outcome and should not be assumed to be the endpoint denominator.

The adverse-event summaries show that serious adverse events were recorded for 7 of 11 participants at risk and other adverse events for 10 of 11 participants at risk. The listed serious-event terms provide additional descriptive information, but they do not establish that the device caused those events. The absence of a concurrent comparator also means the study cannot estimate a relative difference in event frequency or survival against another treatment.

In general, a small single-arm study can document observed outcomes and help describe the experience of the participants included. It cannot, by itself, separate intervention effects from other explanations, and its estimates may be imprecise. For this study, uncertainty cannot be quantified for the primary survival endpoint because the result and its uncertainty interval are not reported in the registry record.

The registry status is TERMINATED, but the reason is not reported in the registry record. Nor does the record establish whether the intended 24-month follow-up was completed. The stated study objective, registered outcomes, and adverse-event figures should not be taken as evidence that all planned outcomes were collected or analyzed. The record supports a limited description of the study and posted safety counts, not a conclusion about comparative effectiveness or causal safety.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the difference between a planned endpoint and a reported result. The registry record clearly identifies six-month survival as the primary endpoint and describes it as a simple proportion. Yet the result itself is not reported in the registry record. Without the numerator, denominator, and an uncertainty measure, the endpoint cannot be interpreted quantitatively.

The design also illustrates the limits of single-arm evidence. A single-arm study can record outcomes in participants receiving an intervention, but it lacks a concurrent group for assessing what might have occurred under an alternative. This makes the study’s conclusions descriptive rather than comparative. That distinction is especially important when outcomes can be influenced by the underlying condition and by other care.

The enrollment of 11 also highlights why precision matters. In general, estimates based on a small group can be highly uncertain, and adverse-event percentages may change substantially with few participants. The registry record does not report confidence intervals for the primary endpoint, so its precision cannot be judged from the posted survival information.

Finally, the record lists multiple outcomes, a TERMINATED status, and no analyses. The statistical plan for multiplicity, missing data, and analysis populations is not reported. These features make it important to distinguish registry descriptions and safety counts from completed, interpretable analyses. The trial matters statistically because it shows how design, reporting completeness, and uncertainty jointly determine what can reasonably be learned from a clinical study.

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 study has no concurrent comparator and is described as non-randomized and single-arm. Consequently, the registry record cannot support a like-for-like comparison with another treatment. This limits causal interpretation of both survival and adverse-event findings.

Enrollment is listed as 11, and the registry record does not report the primary survival result, its analysis denominator, or a measure of uncertainty. It also does not report participant disposition, the number with outcome data at each follow-up time, or how missing observations were handled. The actual completeness of follow-up is therefore unclear.

The study was intended to examine safety and performance over 24 months, but the primary endpoint is survival at six months. The record does not report whether the intended follow-up was completed or provide the two-year survival outcome. Its TERMINATED status is listed, but the reason for termination is not reported in the registry record.

The record lists 16 outcome measures and 0 analyses. The statistical analysis plan, including any approach to multiplicity, the analysis populations, and methods for handling missing data, is not reported in the registry record. Detailed eligibility criteria and fuller methods for adverse-event ascertainment, event timing, recurrence, and attribution are also not reported in the registry record.

These limitations mean that the available information supports only a bounded description of the registered design and posted adverse-event summaries. It does not provide a complete basis for evaluating the primary endpoint, follow-up completeness, comparative effects, or the precision of outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Clinical Trial to Evaluate the HeartWare MVAD® System (MVAdvantage) — NCT01831544.
• Registry record last updated 2025-09-23; status last verified 2022-07.
• Results first posted 2020-04-07.
• 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 record describes a multi-center, prospective, non-randomized, single-arm trial of the HeartWare MVAD® System for advanced heart failure. Enrollment is listed as 11. The study status is TERMINATED; the listed start date is 2015-07-14 and the primary completion date is 2015-09-01.

The primary endpoint is survival at six months, presented as a simple proportion. The survival result is not reported in the registry record. The record lists 16 outcome measures and 0 analyses. It also lists serious adverse events in 7 of 11 participants at risk and other adverse events in 10 of 11 participants at risk.

The reason for termination, analysis populations, missing-data methods, and completion of planned 24-month follow-up are not reported in the registry record. Without a concurrent comparator, the available findings are descriptive and do not establish comparative effects.