Determining the Feasibility of Spinal Cord Neuromodulation for the Treatment of Chronic Heart Failure: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Determining the Feasibility of Spinal Cord Neuromodulation for the Treatment of Chronic Heart Failure (NCT01112579), a randomized phase 2 study. The primary outcome is Evaluate the Reduction in Left-ventricular End Systolic Volume Index (LVESVi) After 6 Months of Spinal Cord Stimulation (SCS) Therapy in the Treatment Arm Compared to the Control Arm..

2. Clinical Question

The record identifies the study as randomized and parallel, and lists 81 for enrollment. The primary measure is a cardiac imaging measure rather than a direct measure of symptoms or daily function. It was accompanied by secondary measures of proBNP and peak oxygen uptake, both assessed from baseline through 6 months. Those measures provide different kinds of information: proBNP is a laboratory marker, while peak oxygen uptake is a measure of exercise capacity.

The registry record's descriptions are limited. It does not report the eligibility criteria, the precise definition of the control condition, or additional information about how participants were recruited. The clinical question can therefore be described from the registered comparison and outcomes, but not expanded into a detailed account of treatment delivery or the characteristics of the participants.

3. Trial Design

The registry record describes a randomized, single-masked, parallel phase 2 study, marked completed. Its stated purpose was to determine the feasibility of spinal cord stimulation as a chronic therapy for systolic heart failure. The sponsor is Medtronic Cardiac Rhythm and Heart Failure. The record lists a start date of 2010-04 and primary completion in 2014-01, and lists 81 for enrollment.

There are treatment and control arms. The treatment intervention is named as the Medtronic PrimeADVANCED Neurostimulator. Although the record lists the same device name for both intervention entries, the arm descriptions are blank, so the control condition and the distinction between the intervention entries are not explained there. The identity of the party masked in this single-masked design is not reported in the registry record.

The primary outcome is the mean change in left-ventricular end-systolic volume index from baseline to 6 months, measured in mL/m2. The posted results include endpoint values for 40 treatment-arm participants and 20 control-arm participants. The record also posts two secondary outcomes: change in proBNP and change in peak oxygen uptake through 6 months. Their reported analysis denominators differ from those for the primary outcome.

The listed enrollment and endpoint denominators describe different registry fields and should not be treated as interchangeable. The record does not report a participant-flow account, reasons for missing endpoint observations, or the analysis population definition. It also does not report the original sample-size justification, detailed allocation procedures, or the statistical analysis plan. Those omissions limit conclusions about how the trial was planned and how closely its posted analyses followed its original protocol.

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 Evaluate the Reduction in Left-ventricular End Systolic Volume Index (LVESVi) After 6 Months of Spinal Cord Stimulation (SCS) Therapy in the Treatment Arm Compared to the Control Arm., measured over Baseline and 6 months.

The primary endpoint is the change in left-ventricular end-systolic volume index, or LVESVi, from baseline to 6 months. It is reported as a mean in mL/m2. The outcome concerns the volume of blood remaining in the left ventricle at the end of contraction, indexed to body surface area. A change in this measure is used to characterize cardiac structure and function, and the registry frames the endpoint as evaluating reduction after spinal cord stimulation.

The primary comparison is the mean change in the treatment arm relative to the mean change in the control arm. The posted arm values are 2.8 for treatment and -3.6 for control, with a reported mean difference of 6.4. The direction of a difference needs to be interpreted against the outcome's coding and the trial's analytic definition. The registry record does not provide additional details about that definition or whether positive values represent an increase or a reduction in the underlying measure.

As a continuous outcome, LVESVi preserves information about the amount of change rather than reducing it to a binary event. It can therefore describe both the average direction and the spread of observed changes. A mean alone does not show how individual participants' values were distributed, and the registry record does not provide individual-level results. Nor does an imaging endpoint alone capture every aspect of heart failure, such as symptoms, function, or events. The primary result should be read as evidence about this specific measured outcome over the stated timeframe, not as a complete account of clinical status.

7. Results Posted in the Registry

• Treatment: mean 2.80 versus -3.60 on control; difference 6.40 (95% CI -1.80 to 14.60), standardized effect d = 0.41; z-test p = 0.126.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Characterize the Change in proBNP Between the Treatment Arm and Control Arm Through 6 Months

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Treatment: mean -32.40 versus 73.80 on control; difference -106.20 (95% CI -817.43 to 605.03), standardized effect d = -0.09; z-test p = 0.770.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Treatment and the control. The interval gives the range of effects that remain compatible with the data.

Characterize the Change in Peak Oxygen Uptake Between the Treatment Arm and Control Arm Through 6 Months

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Treatment: mean 0.60 versus -0.20 on control; difference 0.80 (95% CI -1.55 to 3.15), standardized effect d = 0.21; z-test p = 0.505.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Treatment and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes address different aspects of the study question from the primary cardiac imaging measure: proBNP is a laboratory measure and peak oxygen uptake is a measure of exercise capacity. Across these outcomes, the posted treatment-versus-control estimates are imprecise, and the sponsor-reported intervals include zero. Taken together, the secondary results do not establish a consistent, clearly separated pattern between the arms. They also do not prove that no differences exist.

These outcomes complement the primary result but do not change its status as the prespecified primary question in the registry. They can help describe whether patterns across measures appear coherent, but each measure captures a different construct, and the results should not be treated as interchangeable. The registry record does not report a clinical threshold for interpreting changes in either secondary measure.

Unadjusted secondary findings generally carry less weight than the primary analysis when several outcomes are examined, because repeated testing increases the opportunity for chance findings. The registry record does not report a multiplicity adjustment or a hierarchy for interpreting secondary outcomes. The secondary analyses should therefore be considered exploratory in the absence of reported control of multiplicity. A nominal result, whether favorable or unfavorable, would need cautious interpretation alongside the primary outcome, the uncertainty of each estimate, and the broader study design.

The outcome-specific denominators differ, and the registry record does not explain why. This adds uncertainty when comparing patterns across outcomes: differences in the analyzed sets could contribute to apparent variation between measures. Without a participant-flow account or missing-data analysis, it is not possible to determine how much that issue affects the results. The secondary measures provide context, not independent confirmation of the primary finding.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Characterize the Change in proBNP Between the Treatment Arm and Control Arm Through 6 Months
• Characterize the Change in Peak Oxygen Uptake Between the Treatment Arm and Control Arm Through 6 Months

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous, and the registry reports means and standard deviations for each arm. A mean describes the average observed change in an arm; a standard deviation describes how dispersed individual values are around that average. These summaries provide a compact description of the groups, but they do not show the full shape of the outcome distribution or the observations for individual participants.

What does the mean difference represent?

The treatment-minus-control mean difference compares the two arm means on the outcome's original scale. For the primary endpoint, the posted arm means are 2.8 and -3.6, and the recalculated difference is 6.4 mL/m2. The estimate describes the contrast in average change, not the change experienced by every participant. The meaning of its direction depends on how change was defined and coded. The registry record does not give further detail about that coding.

What does the recalculation use?

The recalculated comparisons are simple, unadjusted re-calculations from the posted arm summaries. They do not incorporate participant-level covariates or the trial's original analytic model. The recalculated primary interval is -1.799 to 14.6, with unadjusted p = 0.126. Because these calculations use summary data, they cannot reproduce an adjusted model that depends on participant-level values. They are useful as a statistical cross-check, but they are not a substitute for the sponsor's reported analysis.

How does ANCOVA differ?

The sponsor reports ANCOVA for the primary outcome and both secondary outcomes, with the parameter described as a mean difference in final values. ANCOVA is a regression method that compares outcome values between groups while adjusting for covariates. In a trial, adjustment may account for baseline outcome values or other prespecified variables, but the covariates used in this study are not reported in the registry record. It is therefore not possible to determine from the record precisely what adjustment was made or to reproduce that model.

The sponsor's primary estimate is 6.4, with a 95% confidence interval from -2.0 to 14.9 and p = 0.3. Its central estimate matches the unadjusted recalculation, while its interval and p-value are not identical. This is not inherently unexpected: estimates and uncertainty can vary with adjustment, analytic populations, or model assumptions. The record does not report enough detail to attribute the difference to any particular cause.

How should a confidence interval be read?

A confidence interval expresses uncertainty around an estimated effect under the assumptions of the analysis. It gives a range of values compatible with the data and method, rather than a guarantee that the true effect lies within that particular interval. The primary sponsor-reported 95% interval extends from -2.0 to 14.9. Because it includes zero, it does not exclude a null difference at the corresponding conventional two-sided testing level. This does not prove no effect; it indicates that the estimate is not precise enough to distinguish the observed contrast from zero under that analysis.

A p-value describes how unusual data at least as inconsistent with a null hypothesis would be if that hypothesis and the model assumptions were true. It is not the probability that the null hypothesis is true, nor a measure of clinical importance. The sponsor's p-value and the recalculated unadjusted p-value come from different analyses and should not be treated as if they were estimates from one identical model.

Why does variation matter?

Standard deviations of 16.0 in treatment and 14.9 in control indicate that individual changes vary within both groups. When outcomes are variable and the analysis groups are limited, the estimated mean difference may be imprecise. The width of an interval reflects this uncertainty as well as the scale and analytic method. An average difference can coexist with considerable overlap in individual outcomes; arm means alone do not show how much the distributions overlap or whether there are subgroups with different patterns.

General statistical point: over-dispersion means the observed variation is greater than a model expects. If a model understates variation, its standard errors can be too small and its confidence intervals too narrow. The posted primary outcome is analyzed as a continuous mean with standard deviations; the registry record does not identify an over-dispersion problem or report a special variance model. This general consideration should not be mistaken for a finding about this trial.

What can and cannot be established from registry summaries?

The posted analysis supplies arm-level means, standard deviations, denominators, and sponsor-reported ANCOVA results. It does not supply participant-level observations, details about missing data, the full protocol, or the complete analysis plan. Those omissions prevent independent reconstruction of the adjusted analysis and prevent evaluation of several assumptions. The results can be described as posted, while conclusions about modeling choices, protocol adherence, or missingness mechanisms remain unavailable.

The sponsor-reported analysis and unadjusted recalculation answer related but not identical statistical questions. The sponsor analysis is the registry's own model-based result. The recalculation illustrates the contrast implied by the posted summary statistics without adjustment. They are complementary descriptions, not interchangeable estimates. The most responsible reading considers the point estimates, interval widths, outcome definitions, analysis methods, and limitations of the available record together.

11. Confidence Intervals and Precision

Precision concerns how narrowly the data and analysis locate an estimated effect. The sponsor-reported primary mean difference is 6.4, with a 95% confidence interval from -2.0 to 14.9. This interval includes zero and spans values on both sides of no difference. It therefore does not pin down a single direction of effect. The interval's breadth is important: the point estimate is only one value among a range compatible with the analysis.

The unadjusted recalculation gives an interval from -1.799 to 14.6. It has a similar central estimate, but it is not the same analysis as the sponsor's ANCOVA. The registry record does not label a confidence level for the recalculated interval, so it should not be assigned one based only on the posted summaries. The sponsor's 95% interval is the explicitly reported confidence interval for the registry analysis.

A confidence interval is not a range containing a known share of individual participant outcomes, and it does not show the range of responses among participants. It describes uncertainty in the estimated group contrast. Nor does an interval crossing zero demonstrate equivalence or rule out a clinically meaningful effect; the registry record does not report an equivalence margin or a threshold for clinical importance.

The trial's endpoint denominators and the variability of the outcome matter to precision, but the registry record does not explain the missing observations or provide a participant-level account. Consequently, the posted interval is the appropriate summary of uncertainty for the reported analysis, while its interpretation remains conditional on the analysis method and the available observations.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total event counts. They are planning illustrations based on the observed effect, rather than the trial's original design calculation. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; each planning scenario uses the stated fraction of the observed effect. The trial's own original sample-size assumptions are not reported in the registry record.

The 80% power column gives the planned number of participants per arm under the stated assumptions for a design with an 80% chance of detecting the chosen effect, if that effect and the model assumptions were correct. The 90% column expresses the corresponding planning target for a higher chance of detection. These are design calculations, not guarantees about results. The curve should be read in the same planning context: it illustrates how the required participants per arm vary with the effect size being targeted.

Planning for a smaller effect requires more participants than planning for a larger effect, because a smaller group difference is harder to distinguish from ordinary variation. The rows using 75% or 50% of the observed effect illustrate that sensitivity to the assumed target. The observed effect itself may be uncertain, particularly when the estimated interval is broad, so planning from it should not be read as a definitive estimate of the effect expected in another study.

This is not observed power. It is a prospective planning illustration calculated from the posted effect estimate and stated assumptions, not a measure of how likely the completed trial was to detect its true effect. The registry record does not report the assumptions used for the trial's original design, so these illustrations cannot establish whether the completed study was adequately sized for its original aims.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 6.400; pooled standard deviation σ = 15.648.
2. n = 2 × (1.96 + 0.842)² × 15.648² / 6.400² = 93.8, rounded up to 94 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 6.4                      # observed difference in means
sigma <- 15.648173849609                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1112579)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 94 (80% power), 126 (90% power)
 75% of observed effect: n per arm = 167 (80% power), 224 (90% power)
 50% of observed effect: n per arm = 376 (80% power), 503 (90% power)
power.t.test: 94.8 
Simulated power at n = 94 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry's sponsor-reported primary analysis is ANCOVA and reports a mean difference in final values of 6.4, with a 95% confidence interval from -2.0 to 14.9 and p = 0.3. The simple unadjusted recalculation from the posted arm summaries also estimates a mean difference of 6.4, with an interval from -1.799 to 14.6 and unadjusted p = 0.126.

The agreement in the central estimate does not make the analyses identical. The recalculation uses the posted means and standard deviations without covariate adjustment, while ANCOVA is a model-based adjusted analysis. Their uncertainty estimates and p-values differ. The registry record does not identify the ANCOVA covariates, so the precise source of the difference cannot be assessed from the record.

The sponsor-reported ANCOVA is the trial's own posted analysis; the recalculation is a separate summary-statistic check. Both intervals include zero, and neither result alone identifies a precise effect. The record does not report enough information to reproduce the sponsor's model or evaluate every modeling choice.

15. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome and two posted secondary outcomes, and reports three analyses. It does not report whether the protocol specified a hierarchy among outcomes, whether any adjustment for multiple comparisons was planned, or how secondary analyses were intended to support conclusions. When several outcomes are tested, the chance of at least one apparently notable result can increase. General statistical practice may address this by defining a primary outcome in advance, adjusting significance criteria, or treating secondary analyses as exploratory. The record does not establish which approach was used in this trial.

The record reports ANCOVA for the posted analyses but does not identify the covariates, model diagnostics, or the full analysis population. It also does not report whether the analyses followed an intention-to-treat principle, whether participants were analyzed as randomized, or whether per-protocol analyses were conducted. The meaning and consequences of these omissions cannot be determined from the posted results alone.

Endpoint denominators vary across outcomes, and the registry record does not provide reasons for missing outcome observations, describe how missing values were handled, or report a sensitivity analysis. Missingness can affect interpretation if the availability of an outcome is related to participant characteristics or outcomes themselves. This is a general concern, not evidence that such a bias occurred in this study.

The record does not report interim analyses, stopping rules, the original sample-size justification, or the trial's detailed statistical analysis plan. It is therefore not possible to establish whether these procedures were used or how they may have affected analysis choices. These reporting gaps limit assessment of prespecification and robustness; they do not, by themselves, show that the reported analysis was inappropriate.

16. Safety Results

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

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: decompensated heart failure (38.1%), ventricular tachycardia (12.5%), pneumonia (12.5%), cardiogenic shock (8.3%), lead dislodgement (7.1%).

The adverse-event record lists serious adverse events affecting 30 of 42 at risk in the treatment group and 16 of 24 at risk in the control group. For other adverse events, it lists 19 of 42 at risk in treatment and 12 of 24 at risk in control. These are the registry's counts and denominators; they are not the primary efficacy analysis denominators. The record does not provide further detail about event timing, severity categories beyond the serious classification, or how multiple events in one participant were counted.

The serious-event terms most frequently listed include Decompensated Heart Failure at 38.1%, Ventricular Tachycardia at 12.5%, Pneumonia at 12.5%, Cardiogenic Shock at 8.3%, Lead Dislodgement at 7.1%, and Chest Pain at 4.8%. The registry record does not clarify the denominator or counting convention for these term percentages in the information, so they should be read as listed rather than converted into participant-level risks.

Death counts are not reported in the registry record. These figures describe reported adverse events; they do not establish that an event was caused by the device or study intervention. The record does not provide an analysis comparing safety risks between groups, and differences in these counts should not be interpreted as a causal comparison.

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

The posted results describe a randomized phase 2 study of spinal cord stimulation for chronic heart failure, with change in LVESVi as the primary outcome. The reported treatment-control mean difference is 6.4, but the sponsor's 95% confidence interval, from -2.0 to 14.9, includes zero and allows a range of possible contrasts. The unadjusted recalculation likewise has an interval spanning zero. The data therefore do not provide a precise estimate that settles the direction or magnitude of the difference.

This does not mean the study proves that the intervention has no effect. A nonsignificant result can reflect uncertainty as well as a small or absent effect; the interval expresses the range of effects compatible with the analysis. Conversely, a positive point estimate is not proof of benefit. The record does not report a clinically important difference threshold, so statistical estimates cannot be translated into a claim about clinical importance from these data alone.

The study's registered purpose was to determine feasibility. Its primary outcome is an imaging measure over 6 months, with proBNP and peak oxygen uptake as secondary measures. These outcomes do not represent every relevant dimension of heart failure. The registry record does not supply detailed participant characteristics, the control procedures, missing-data methods, or the full statistical plan, all of which would help frame the results.

Interpretation should remain limited to the reported groups, measures, and timeframe. The posted results do not establish how findings would generalize to other populations or treatment settings, and the adverse-event counts do not determine causation. The results are best understood as a record of uncertain between-arm estimates from a feasibility-focused trial, rather than a definitive conclusion about efficacy or safety.

18. Why This Trial Matters Statistically

This trial illustrates why a point estimate should be read together with its uncertainty. The primary mean difference is 6.4, but the sponsor-reported 95% confidence interval ranges from -2.0 to 14.9 and includes zero. The point estimate alone might draw attention to one direction, while the interval shows that the posted analysis does not locate the effect precisely enough to rule out other possibilities.

It also illustrates the distinction between an adjusted sponsor analysis and an unadjusted recalculation from summary statistics. The two approaches produce similar central estimates but different intervals and p-values. Knowing which analysis generated a result matters: a recalculation can check the arithmetic implied by arm summaries, but it cannot replace the trial's adjusted model or reveal its covariates.

Different denominators across the primary and secondary outcomes, and between efficacy and adverse-event summaries, also matter statistically. Without participant flow and missing-data information, readers cannot fully assess which observations contribute to each result or whether analyzed groups differ. The registry record's omissions constrain interpretation without proving that the estimates are biased.

Finally, the planning illustrations show how sample-size requirements depend on the effect chosen for detection and on assumptions about design. They do not describe the completed trial's observed power or disclose its original design rationale. Together, these features make the record useful for understanding estimation, uncertainty, and reporting limits in a clinical trial, while underscoring why statistical significance, clinical importance, and study purpose are distinct questions.

19. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry descriptions leave important aspects of the trial's clinical and analytic context unspecified. The arm descriptions are blank, and although both intervention entries name the Medtronic PrimeADVANCED Neurostimulator, the control procedures and the distinction between the entries are not described. The masking field says single, but the masked party is not identified. Eligibility criteria and detailed participant characteristics are not reported in the registry record.

The record lists 81 for enrollment, while the numbers contributing to the posted outcomes vary. It does not provide a flow of participants through the study, reasons for missing measurements, or a missing-data strategy. It is not possible to determine whether missingness could have influenced the observed estimates. The analysis population and whether analyses followed an intention-to-treat approach are also not reported.

The sponsor's ANCOVA results are posted, but the covariates and model details are not reported. The full protocol, original sample-size justification, interim analysis procedures, stopping rules, and multiplicity plan are not reported in the registry record. These gaps limit independent evaluation of prespecification and analytic robustness. They should be treated as limits of the available record, not as evidence that a particular procedure was or was not used.

The primary outcome is a measure of LVESVi change through 6 months, and the secondary outcomes are proBNP and peak oxygen uptake. The record does not report a clinical importance threshold for these measures. The results therefore support description of the measured outcomes but do not by themselves establish the practical importance of the estimated differences. The study's phase 2 feasibility purpose also places the efficacy estimates in an exploratory context.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Determining the Feasibility of Spinal Cord Neuromodulation for the Treatment of Chronic Heart Failure — NCT01112579.
• Registry record last updated 2015-10-29; status last verified 2015-10.
• Results first posted 2015-10-29.
• 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.

23. Record Summary

NCT01112579 is a completed randomized, single-masked, parallel phase 2 study sponsored by Medtronic Cardiac Rhythm and Heart Failure. The registry lists enrollment of 81, a start date of 2010-04, and primary completion in 2014-01. The stated purpose was to assess feasibility of spinal cord stimulation as a chronic therapy for systolic heart failure.

The primary outcome was mean change in LVESVi from baseline to 6 months. The sponsor-reported ANCOVA estimate was 6.4, with a 95% confidence interval from -2.0 to 14.9 and p = 0.3. The interval includes zero and reflects substantial uncertainty about the between-arm difference. The posted secondary outcomes were change in proBNP and peak oxygen uptake; their estimates are also imprecise.

The registry record does not report the full statistical plan, analysis populations, missing-data methods, or original sample-size assumptions. Adverse-event counts are posted, but they do not establish causation. Overall, the record describes a feasibility-focused trial with uncertain estimates for its reported outcomes.