A Study of Mavacamten in Obstructive Hypertrophic Cardiomyopathy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Mavacamten in Obstructive Hypertrophic Cardiomyopathy (NCT05414175), a na phase 3 study. The primary outcome is Change From Baseline in Post-exercise Left Ventricular Outflow Tract (LVOT) Peak Gradient at Week 30.

2. Clinical Question

In statistical terms, the study is organized around a within-participant change over time. It does not directly estimate a comparative treatment effect. The primary measure is a continuous physiological outcome recorded in millimeters of mercury, with the endpoint described as a mean change. The registry record says that echocardiograms were obtained at baseline and Week 30 following a study-specified exercise protocol. It also specifies that only participants with data at the relevant time points were analyzed. The clinical question is therefore focused on the observed change in this measure during the study, not on whether that change differs from what would have occurred without mavacamten.

3. Trial Design

This was a Phase 3, open-label, single-arm clinical study sponsored by Bristol-Myers Squibb. The registry identifies the study as completed and lists enrollment of 38 participants. The study began on 2022-08-19, with primary completion on 2023-11-27. Its stated purpose was to evaluate the effectiveness, safety, and tolerability of a 30-week course of mavacamten and the long-term effects of mavacamten in Japanese participants with symptomatic obstructive hypertrophic cardiomyopathy.

All participants were assigned to the mavacamten group. Allocation is recorded as not applicable, consistent with the single-group model, and masking is listed as none. There was no randomized control arm. Accordingly, the design can describe the course of outcomes in the enrolled group, but it cannot directly compare those outcomes with a concurrent group receiving placebo, usual care, or another intervention.

The primary outcome was change from baseline in post-exercise left ventricular outflow tract peak gradient at Week 30. The registry describes this as a mean continuous measure, with standard deviation as the measure of dispersion, and gives the unit as millimeters of mercury. Echocardiograms were collected at baseline and Week 30 after a study-specified exercise protocol. The registry definition of baseline uses the last non-missing assessment before the first dose when measurement and first-dose times are available; otherwise, it uses the last non-missing assessment on or before the first dose.

Secondary outcomes include changes in the KCCQ-23 Clinical Summary Score, NT-proBNP, cardiac troponin I, and cardiac troponin T at Week 30, as well as the percentage of participants with at least one class improvement in NYHA Functional Class from baseline to Week 30. The registry record does not report detailed protocol procedures beyond the descriptions of these outcomes and the primary endpoint.

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:

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat population. Only those participants with data available at the specified time points were analyzed.

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 Change From Baseline in Post-exercise Left Ventricular Outflow Tract (LVOT) Peak Gradient at Week 30, measured over At Baseline and Week 30.

The primary endpoint is change from baseline in post-exercise left ventricular outflow tract peak gradient at Week 30, measured in millimeters of mercury. The gradient is a continuous measure of the pressure difference associated with blood flow through the left ventricular outflow tract. In general, measuring it after exercise can characterize the gradient under an exertional condition, which is relevant when evaluating obstructive physiology. The registry specifies that the measurement came from echocardiograms obtained after a study-specified exercise protocol and read by Doppler echocardiography.

Change from baseline summarizes how the measure differs at the follow-up assessment from the participant’s baseline value. Reporting the mean change gives an average direction and magnitude across the analyzed participants; the standard deviation describes how much individual changes vary around that average. These are distinct pieces of information: the mean describes the group’s average change, while the standard deviation describes participant-level spread.

The registry identifies the endpoint as a mean and names standard deviation as its dispersion measure, but it does not report the observed mean change or standard deviation in the registry record for this analysis. A confidence interval, p-value, and other inferential results are also not reported in the registry record. Without those results, the endpoint’s direction, magnitude, and statistical precision cannot be assessed from the registry information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary outcome as a mean change in a continuous measure. The endpoint is the change from baseline in post-exercise left ventricular outflow tract peak gradient at Week 30. In general, a continuous endpoint can take a range of values, rather than placing each participant into a small set of categories. A mean change summarizes the average difference between the follow-up and baseline measurements among the analyzed participants. The registry gives millimeters of mercury as the unit and standard deviation as the dispersion measure.

What does the mean change describe?

For each participant with the required measurements, change from baseline represents the follow-up measurement relative to that participant’s baseline. A group mean of those changes describes the average within-participant change. This is not the same as a comparison between two independent groups. Because the study is single-arm, the mean change is a description of the observed trajectory in the mavacamten group, rather than a treatment-versus-control contrast.

In general, a mean can be influenced by unusually large or small individual changes. The standard deviation helps describe the spread of individual observations around the mean. It does not, by itself, quantify uncertainty in the estimated mean. A confidence interval is a different summary: it expresses the statistical uncertainty around an estimate under the assumptions of the analysis. The registry record identifies standard deviation for the primary measure, but a numerical standard deviation and a confidence interval are not reported in the registry record.

How should the baseline measurement be understood?

The baseline definition is based on timing relative to the first dose. When the time of the measurement and the time of the first dose are available, baseline is the last non-missing assessment before the first dose. Otherwise, the definition uses the last non-missing assessment on or before the first dose. This definition makes the selected baseline value depend on the documented assessment and dosing times. The record describes the rule but does not report how many participants required the alternate timing rule.

The primary assessment was made at baseline and Week 30. The registry says the post-exercise gradient was measured from echocardiograms obtained after a study-specified exercise protocol and read by Doppler echocardiography. Standardizing a measurement procedure can help make repeated observations more comparable in general, but the details of the exercise protocol and reading procedures are not reported in the registry record.

What does the analysis population include?

The primary endpoint population is called the intent-to-treat population. The accompanying definition says that only participants with data available at the specified time points were analyzed. The label and the operational description should therefore be read together: the record identifies an intent-to-treat population but also states that the endpoint analysis requires available measurements. The number of participants with usable data at both time points is not reported in the registry record.

In general, excluding participants without endpoint data can make an analysis less representative if the reasons for missingness are related to outcome values or participant characteristics. Missing-data methods can include assumptions and procedures intended to address incomplete observations, but the specific approach depends on the study and analysis plan. The registry record does not report imputation, sensitivity analyses, or another procedure for missing primary endpoint data.

What can be inferred from the design?

The study has one treatment group and no masked or randomized comparator. The primary analysis therefore concerns change over time within the enrolled group. General statistical interpretation of a single-arm change should distinguish a measured before-and-after difference from a causal treatment effect. Without a concurrent comparator, the observed course cannot rule out other explanations for change, including natural variation over time or measurement variation. The registry record does not report an adjusted causal analysis or a model that would establish a comparative effect.

The primary endpoint is summarized as a mean, but the exact statistical test or model used to analyze it is not reported in the registry record. The record also does not report the confidence level for an interval estimate, a prespecified hypothesis test, or an approach to any model assumptions. A p-value, if reported, would address compatibility of the data with a specified statistical hypothesis under the analysis assumptions; it would not by itself describe the size or clinical importance of an effect. No primary endpoint p-value is reported in the registry record.

Why do planning calculations differ from observed results?

General sample-size planning asks how many participants might be needed under chosen assumptions to detect a specified effect with a chosen statistical approach. The registry describes a planning illustration using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. The illustration is not the design justification for this single-arm trial, and it does not represent observed power. The registry record does not report numerical planning results or the assumptions used to determine enrollment for the trial itself.

When outcomes are analyzed, precision depends on the observed data and the analysis method, not simply on the enrollment count. A planning calculation cannot substitute for a confidence interval around the actual estimate. No calculated sample-size values, observed endpoint estimate, or interval estimate are reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Mavacamten")
n   <- c(35)
m   <- c(-60.6963)
sp  <- c(31.55674)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Mavacamten  35  -60.696  31.557  -71.536  -49.856

11. Multiplicity, Missing Data and Analysis Populations

The registry lists several secondary outcomes in addition to the primary endpoint. These include change in KCCQ-23 Clinical Summary Score, improvement in NYHA Functional Class, and changes in NT-proBNP, cardiac troponin I, and cardiac troponin T at Week 30. Examining multiple outcomes creates a general multiplicity issue: when many statistical hypotheses are assessed, the chance of at least one apparently notable result can increase if each is interpreted separately. Methods such as adjustment procedures or a prespecified hierarchy can address that issue, but the registry record does not report a multiplicity strategy.

Numerical results and analysis details for the listed secondary outcomes are not reported in the registry record. The record indicates 6 outcome measures and no analysis entries in the information available for this review. It does not report which secondary outcomes were formally tested, how they were prioritized, or whether any adjustment was planned or performed. The sample-size justification and detailed statistical analysis plan are also not reported in the registry record.

For the primary endpoint, the stated population is the intent-to-treat population, with analysis limited to participants who had data at the specified time points. The registry does not state how many participants had complete primary endpoint data, why any data were missing, or how missing values were handled. No imputation procedure or sensitivity analysis is reported. In general, complete-case results can be affected if missingness is related to participants’ outcomes or other characteristics, so the availability and handling of follow-up measurements are relevant to interpretation.

The record gives a baseline definition based on the last non-missing assessment before the first dose when timing information is available, or the last non-missing assessment on or before the first dose otherwise. It does not report how many observations were selected under either part of that rule. These omissions limit assessment of the analysis population and of the robustness of the endpoint result, which itself is not reported in the registry record.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: atrial fibrillation (2.6%), macular oedema (2.6%), cholangitis (2.6%), cholecystitis acute (2.6%), covid-19 (2.6%).

The registry lists 6 participants with serious adverse events among 38 at risk in the mavacamten group. It lists 20 participants with other adverse events among 38 at risk and reports 0 deaths. These are descriptive counts during the study, not comparisons between treatment groups. Because the study had no control arm, the counts do not show how the event frequency compares with an untreated or alternative-treatment group.

The serious adverse event terms listed are atrial fibrillation, macular oedema, cholangitis, cholecystitis acute, COVID-19, and colonic abscess. Each is reported at 2.6%. The record does not give a separate participant count for each listed term in the registry record for this analysis. A participant may experience more than one event, so event terms should not automatically be interpreted as mutually exclusive groups of people.

Adverse event counts do not establish causation. The registry information does not report whether investigators considered each event related to mavacamten, nor does it give comparative safety estimates. The figures should be read as events recorded in this single study group, with the study’s size and lack of a comparator kept in mind.

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

The trial asks a defined question about change in post-exercise left ventricular outflow tract peak gradient from baseline to Week 30 among participants receiving mavacamten. Its design and endpoint description make clear what the investigators intended to measure. However, the numerical primary endpoint result is not reported in the registry record. It is therefore not possible to describe whether the mean changed upward or downward, how large the change was, or how precisely it was estimated.

Even if a within-group change were reported, a single-arm design would not by itself establish what would have happened over the same period without mavacamten. General influences such as natural variation over time, measurement variation, and changes associated with study participation cannot be separated from treatment effects using a concurrent comparison in this design, because there is no comparator group. The record does not describe a causal analysis that resolves this limitation.

The study also lists patient-reported, functional, and biomarker outcomes, but their numerical results are not reported in the registry record addressed. Their presence indicates that the study assessed several dimensions, but does not allow conclusions about the observed values or their precision. The record does not specify how any multiplicity across outcomes was handled.

The safety counts describe the experience recorded in the enrolled group: 6 participants with serious adverse events, 20 with other adverse events, and 0 deaths among 38 at risk in the respective summaries. Those data are descriptive and do not establish that mavacamten caused a particular event, nor do they provide a comparative estimate of risk. The listed serious event terms, each reported at 2.6%, should be interpreted within this limited study context.

Overall, the registry information supports describing the study’s population, design, intended endpoint, and listed safety counts. It does not support a numerical conclusion about the primary endpoint’s change or its precision, because those results are not reported in the registry record. The study design also means that any observed change would remain a within-group description rather than a controlled estimate of treatment effect.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of how a clearly defined endpoint and a single-arm design answer different kinds of questions. The primary endpoint specifies a continuous measure, a baseline reference, a follow-up time, and a unit. These choices define what is to be summarized. The design, in turn, defines what can be compared: participants’ measurements over time within one group, not outcomes between randomized treatment groups.

The distinction is important for researchers and readers. A mean change can be useful for describing the observed trajectory, while a comparison group is generally needed to estimate how that trajectory differs from an alternative course. In general, a before-and-after observation can reflect treatment exposure along with other changes over time. The registry record has no concurrent control group to separate those influences.

The endpoint description also highlights the need to interpret analysis populations carefully. The record calls the population intent-to-treat but specifies that only participants with data at the relevant time points were analyzed. Knowing the number of participants contributing data, reasons for missing measurements, and methods for handling missingness helps readers assess the reach and robustness of an estimate. Those details are not reported in the registry record.

Finally, the record shows why registering outcomes and reporting results are separate parts of transparency. Several secondary outcomes and safety summaries are identified, but numerical endpoint results and detailed analysis choices are not reported in the information available for this analysis. Without the primary estimate and a measure of its precision, readers cannot evaluate the size or uncertainty of the endpoint change. The design, outcome definition, and safety counts remain interpretable as descriptions, but they do not replace the missing efficacy estimate or a controlled comparison.

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 central limitation for interpreting the primary endpoint is that its numerical result is not reported in the registry record. The registry identifies the mean change and standard deviation as the planned summary, but does not give the observed mean, its variability, or an interval estimate. Thus neither magnitude nor precision can be assessed. The analysis sample size at Week 30 is also not reported, even though the record says that only participants with data at the required time points were analyzed.

The single-arm, open-label design limits comparative interpretation. There is no randomized control group, and no masking. General statistical concerns in this setting include possible differences in measurement or reporting over time and other influences on the outcome that cannot be distinguished from treatment exposure. The record does not report a comparative analysis capable of addressing these issues.

The registry information does not describe the primary endpoint’s specific statistical test or model, missing-data procedures, sensitivity analyses, or multiplicity handling. Although several secondary outcomes are listed, their numerical findings are not reported in the information available for this analysis. These gaps limit assessment of how the results were analyzed and whether conclusions across multiple outcomes were protected against chance findings.

The study enrolled 38 participants, and the safety summaries are descriptive. The record does not provide a control-group safety comparison or event-attribution details in the registry record for this analysis. It also does not report the trial’s sample-size justification, interim analyses, or full statistical analysis plan. The study summary mentions long-term effects, but long-term outcome results and their analysis are not reported in the registry record addressed.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Mavacamten in Obstructive Hypertrophic Cardiomyopathy — NCT05414175.
• Registry record last updated 2026-01-27; status last verified 2026-01.
• Results first posted 2024-12-04.
• 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

NCT05414175 is a completed Phase 3, open-label, single-arm study of mavacamten in adults with symptomatic obstructive hypertrophic cardiomyopathy. The record lists Bristol-Myers Squibb as sponsor and enrollment of 38. The study began on 2022-08-19, with primary completion on 2023-11-27. Its stated aim was to evaluate a 30-week course of mavacamten and long-term effects in Japanese participants.

The primary endpoint was change from baseline in post-exercise left ventricular outflow tract peak gradient at Week 30, summarized as a mean with standard deviation. The registry record does not report the numerical primary endpoint result, its precision, or detailed statistical methods. Safety summaries list 6 participants with serious adverse events, 20 with other adverse events, and 0 deaths among 38 at risk.