This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Left Bundle Area Versus Selective His Bundle Pacing (NCT04093414), a randomized na study. The primary outcome is Ventricular Capture Threshold, 3 Months Unipolar or Bipolar.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04093414 |
| Phase | NA |
| Condition | Bradycardia, Sinus Node Dysfunction, Atrioventricular Block |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 9 |
| Arms in the primary outcome | 2 |
| Lead sponsor | David Haines, MD |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with bradycardia, sinus node dysfunction, or atrioventricular block who volunteered and were eligible for the study. The registry describes a single-center pilot and records enrollment of 9 participants. Detailed eligibility criteria and the characteristics of the enrolled participants are not reported in the registry record.
Intervention
The Left Bundle Area Pacing arm received pacemaker wires placed in the left bundle branch area. The intervention listing names a Select Secure pacing lead. The brief summary says participants would be randomized to a wire position and that multiple positions in the heart would be studied during pacemaker insertion; further procedural details are not reported in the registry record.
Comparator
The comparator was Selective or Non Selective His Bundle Pacing, described as pacemaker wires placed in the Bundle of His. The study was randomized, open label, and parallel, with no masking. The registry does not report additional details about how treatment assignment was generated or concealed.
Primary question
The primary endpoint asks what ventricular capture threshold was measured at 3 months in unipolar or bipolar output modes. The threshold is the minimum pacemaker signal amplitude that consistently captures the ventricular myocardium, expressed in volts. The study therefore compares a device-measured electrical threshold between the pacing approaches; the registry does not report a formal inferential result for that comparison.
3. Trial Design
The registry describes LEFTBASH as a single-center, open-label, randomized pilot study with a parallel design. It records no masking and lists the phase as NA. Enrollment was 9. The recorded study start date is 2019-10-07, and the primary completion date is 2022-02-14. The study status is TERMINATED; the reason for termination is not reported in the registry record.
Participants were randomized to Selective or Non Selective His Bundle Pacing or Left Bundle Area Pacing. The arm descriptions identify the intended lead locations: the Bundle of His and the left bundle branch area. The intervention listing names a Select Secure pacing lead. The brief summary describes a one-year study period and an ultrasound of the heart to assess the effect of pacing on the heart. It also describes studying multiple heart positions during pacemaker insertion. More detail about the sequence of procedures, follow-up visits, or the randomization process is not reported in the registry record.
The primary outcome is ventricular capture threshold at 3 months, measured in volts in unipolar or bipolar output modes. The registry lists 22 outcome measures, including the primary outcome and secondary measures concerning left ventricular ejection fraction, stroke volume, and mechanical dyssynchrony during intrinsic conduction. The posted arm-level primary outcome summaries include 3 participants in the His Bundle Pacing group and 5 in the Left Bundle Area Pacing group. Those arm counts do not account for the full recorded enrollment, and the reason is not reported in the registry record.
The registry lists the study as terminated, but does not report whether termination affected follow-up, outcome collection, or the planned analysis. The study protocol, sample-size justification, and detailed statistical analysis plan are not reported in the registry record.
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.
3 Month Follow up
| Stage | Selective or Non Selective His Bundle Pacing | Left Bundle Area Pacing |
|---|---|---|
| STARTED | 3 | 6 |
| COMPLETED | 3 | 5 |
| NOT COMPLETED | 0 | 1 |
Reasons for not completing this period:
| Reason | Selective or Non Selective His Bundle Pacing | Left Bundle Area Pacing |
|---|---|---|
| Physician Decision | 0 | 1 |
6month Follow up
| Stage | Selective or Non Selective His Bundle Pacing | Left Bundle Area Pacing |
|---|---|---|
| STARTED | 3 | 5 |
| COMPLETED | 2 | 2 |
| NOT COMPLETED | 1 | 3 |
Reasons for not completing this period:
| Reason | Selective or Non Selective His Bundle Pacing | Left Bundle Area Pacing |
|---|---|---|
| Physician Decision | 1 | 3 |
12 Month Follow up
| Stage | Selective or Non Selective His Bundle Pacing | Left Bundle Area Pacing |
|---|---|---|
| STARTED | 2 | 2 |
| COMPLETED | 2 | 2 |
| NOT COMPLETED | 0 | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Selective or Non Selective His Bundle Pacing | Left Bundle Area Pacing | Total |
|---|---|---|---|---|
| Participants analysed | 3 | 6 | 9 | |
| Age, Continuous | years | 80.67 (SD 9.02) | 78.83 (SD 9.7) | 79.44 (SD 8.95) |
| Sex: Female, Male: Female | Participants | 1 | 2 | 3 |
| Sex: Female, Male: Male | Participants | 2 | 4 | 6 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States | participants | 3 | 6 | 9 |
6. Primary Endpoint
The registry lists the primary outcome as Ventricular Capture Threshold, 3 Months Unipolar or Bipolar, measured over 3 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | volts |
| Endpoint classification | Continuous Endpoint |
Ventricular capture threshold is the minimum amplitude of the pacemaker’s electrical signal that consistently produces capture of the ventricular myocardium: a normal ventricular contraction after electrical depolarization. The registry defines the measurement using a 1.0 millisecond pulse width setting and reports the unit as volts. The measurement is recorded by the pacemaker and interrogated at 3 months after implantation.
The threshold is used to describe the electrical output needed for consistent ventricular capture. As a general statistical and device-measurement concept, lower threshold readings indicate that less signal amplitude was needed to reach the specified capture response under the measurement conditions. The registry description says pacemaker settings are programmed using the threshold with a safety margin and may be readjusted over time if clinically necessary. That description explains the endpoint’s practical relevance; it does not establish that a difference between study arms would translate into a particular battery-life or clinical outcome.
The primary endpoint is a continuous measure, summarized in the registry as a mean with a standard deviation. It is measured at 3 months, rather than being a direct measure of symptoms, hospitalization, or long-term heart function. The registry does not report a confidence interval or an inferential test for the between-arm primary comparison.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry reports a mean ventricular capture threshold of 0.66 volts, with a standard deviation of 0.14, among 3 participants in the Selective or Non Selective His Bundle Pacing arm. For the Left Bundle Area Pacing arm, it reports a mean of 0.65 volts, with a standard deviation of 0.13, among 5 participants. These are descriptive summaries of the posted observations at 3 months.
The two reported means are numerically similar. The standard deviations describe the spread of measurements within each arm; they are not confidence intervals and do not directly quantify the precision of the difference between arms. The registry does not report a confidence interval, standard error, or p-value for this comparison. It also records no analyses for the primary endpoint. Therefore, the posted summaries do not establish how precisely the arms differ, or whether any observed difference is distinguishable from sampling variation.
The very small arm-level samples make the descriptive estimates sensitive to the measurements of individual participants. That is a general statistical consideration, not a claim about the values of any unreported individual observations. The registry’s overall enrollment is 9, whereas the posted primary outcome summaries include 3 and 5 participants in the respective arms. The reason the outcome summaries do not include the full recorded enrollment is not reported in the registry record. No explanation of missing measurements or analysis-population definitions is reported.
The study is identified as a pilot, and the posted primary result is best read as an initial description of measured thresholds rather than a definitive comparison. The registry does not state a minimum meaningful difference or a decision threshold for interpreting the endpoint. It also does not report results for battery life or a long-term clinical outcome as part of this primary comparison. The findings therefore describe the posted capture-threshold measurements and their observed variability, without establishing broader effects.
9. Statistical Methods Explained
The primary endpoint is continuous: each measurement is a voltage value, and the registry reports a mean and standard deviation for each arm. A mean describes the average of the observed values in an arm. A standard deviation describes how dispersed those observations are around their mean. It is not a measure of uncertainty in the mean itself, and it should not be read as a range containing all participants’ values.
What can arm-level summaries show?
Arm-level means allow a descriptive comparison of the recorded groups. In this study, the posted means are 0.66 volts for Selective or Non Selective His Bundle Pacing and 0.65 volts for Left Bundle Area Pacing. The corresponding standard deviations are 0.14 and 0.13, with reported arm sample sizes of 3 and 5. These summaries do not reveal the individual observations or their distribution. Without individual data or a reported model, the shape of the data and the influence of individual measurements cannot be assessed.
A confidence interval is a statistical interval intended to express uncertainty around an estimate under a specified method and assumptions. It is useful because a point estimate alone does not show how precisely a difference has been estimated. No confidence interval for the arm comparison is reported in the registry record. The record also does not report a standard error or inferential test for that comparison. The means and standard deviations should therefore be treated as descriptive, not as evidence of a statistically established between-arm effect.
Why does the sample size matter?
With small groups, each observation can have substantial influence on an arm’s mean and standard deviation. This is a general property of estimates from small samples. The posted primary outcome summaries include 3 participants in one arm and 5 in the other, while overall enrollment is 9. The reason for the difference between the recorded enrollment and these outcome counts is not reported. The registry does not give enough information to determine whether it reflects unavailable measurements, exclusions from an analysis population, or another reason.
The registry describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It specifies that the effect to detect is a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the trial was designed with those assumptions. The actual study sample-size justification and the values for the planning illustrations are not reported in the registry record.
What does over-dispersion mean in general?
Over-dispersion is a general concept for data whose variability is greater than a statistical model expects. It is often discussed for count outcomes and does not, by itself, describe this continuous voltage endpoint. The registry reports standard deviations for the primary measure but does not report a model or a specific assessment of distributional assumptions. No claim about over-dispersion or a model adjustment can be made for this comparison from the registry record.
What is absent from the inferential result?
The registry records no analyses for the primary comparison and notes that values were missing or not estimable for a two-arm comparison of a continuous endpoint. It does not identify that note as a specific result for the primary measure. No adjusted analysis, covariate set, hypothesis-testing procedure, or missing-data method is reported. Consequently, no adjustment or alternative analysis should be inferred from the arm summaries. The posted means and standard deviations can be read as descriptive data, while uncertainty about the between-arm comparison remains unquantified 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.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Selective or Non Selective His Bundle Pacing | 3 | 0.660 | 0.140 | 0.312 to 1.008 |
| Left Bundle Area Pacing | 5 | 0.650 | 0.130 | 0.489 to 0.811 |
R code and output
arm <- c("Selective or Non Selective His Bundle Pacing", "Left Bundle Area Pacing")
n <- c(3, 5)
m <- c(0.66, 0.65)
sp <- c(0.14, 0.13)
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 Selective or Non Selective His Bundle Pacing 3 0.660 0.140 0.312 1.008
CARM Left Bundle Area Pacing 5 0.650 0.130 0.489 0.81111. Multiplicity, Missing Data and Analysis Populations
The registry lists 22 outcome measures and 21 secondary outcomes as posted. The secondary outcomes include left ventricular ejection fraction, stroke volume, and measures of mechanical dyssynchrony during intrinsic conduction. No secondary analysis results are described in the available record details, and the record lists 0 analyses. A multiplicity procedure, such as a method for accounting for multiple statistical comparisons, is not reported in the registry record. It is therefore not possible to determine whether secondary outcomes were treated as exploratory, whether any adjustment was planned, or how multiple results were intended to be interpreted.
The registry reports arm-level means and standard deviations for the primary outcome, but the reason that the arm summaries include 3 and 5 participants while enrollment is 9 is not reported. The registry does not describe missing observations, withdrawals, exclusions, or the handling of measurements that were not collected or could not be used. A missing-data method and an analysis population definition are not reported in the registry record. It is not possible to infer whether the primary summaries reflect all randomized participants, participants with a measurement at 3 months, or another population.
The record notes that values were missing or not estimable for a two-arm comparison of a continuous endpoint. It does not identify which endpoint or comparison this note concerns. The registry also does not report interim analyses, stopping rules, or a detailed statistical analysis plan. These omissions limit interpretation of how the outcomes were selected, how incomplete data were handled, and whether any analyses were planned beyond the descriptive summaries.
12. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Selective or Non Selective His Bundle Pacing | 0 | 3 | 0.0% |
| Left Bundle Area Pacing | 0 | 6 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Selective or Non Selective His Bundle Pacing | 0 of 3 |
| Left Bundle Area Pacing | 0 of 6 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Selective or Non Selective His Bundle Pacing | 0 of 3 |
| Left Bundle Area Pacing | 0 of 6 |
The registry lists 0 serious adverse events among 3 participants at risk in the Selective or Non Selective His Bundle Pacing group, and 0 among 6 participants at risk in the Left Bundle Area Pacing group. It also lists 0 other adverse events among 3 and 6 participants at risk, respectively, and 0 deaths in both groups. The serious adverse event terms list is empty.
These figures describe the event counts and risk denominators entered in the registry. They mean that no events are recorded in those listed categories and risk sets; they do not establish that no adverse events occurred outside the recorded reporting categories or observation period. The registry does not report the definition of each event category, the exact safety follow-up period, or additional detail on how participants were counted as at risk.
The safety denominators differ from the primary outcome arm counts: the safety record lists 3 and 6 participants at risk, while the primary outcome summaries list 3 and 5 participants. The reason for this difference is not reported in the registry record. These safety counts should not be treated as if they resolve the missing explanation for the primary outcome counts or as evidence about comparative risk.
13. What the Result Does, and Does Not, Mean
The posted result describes ventricular capture threshold at 3 months in two randomized pacing groups. The mean was 0.66 volts in the Selective or Non Selective His Bundle Pacing arm and 0.65 volts in the Left Bundle Area Pacing arm. The reported standard deviations were 0.14 and 0.13, and the outcome summaries included 3 and 5 participants, respectively. These numbers characterize the recorded measurements; the registry does not provide an inferential comparison or a confidence interval.
The result does not establish whether the approaches differ in capture threshold. Without a reported interval or test, the precision of the between-arm comparison cannot be judged from the arm means alone. The registry also does not identify a threshold for a meaningful difference, so it does not support judging the observed means against a predefined clinical criterion.
The primary endpoint is an electrical device measurement. Although the brief summary describes interest in pacing efficiency, battery life, and heart function, the posted primary outcome is not a direct measurement of battery life, hospitalization, or long-term cardiac outcomes. The registry lists secondary echocardiographic measures, but the corresponding results are not described in the record details. The primary threshold summaries cannot substitute for those outcomes.
The study is a randomized pilot with enrollment of 9 and status TERMINATED. The reason for termination and its implications for the outcome collection are not reported. The result should therefore be understood as a small set of descriptive observations, with important uncertainty about the comparison and the analysis population. It neither establishes benefit nor establishes a lack of benefit for either pacing approach.
14. Why This Trial Matters Statistically
This study is statistically notable because it places a device-measured continuous endpoint in a randomized pilot comparison of two pacing locations. The registry defines the primary outcome in operational terms: the minimum pacemaker signal amplitude that consistently captures the ventricular myocardium at a specified pulse width, assessed at 3 months. A clearly defined measurement can support reproducible reporting, but interpretation still depends on how many participants contributed usable measurements and how uncertainty is quantified.
The record makes the distinction between descriptive and inferential evidence especially important. It reports arm means and standard deviations, but no confidence interval, p-value, or analysis for the primary comparison. The arm-level sample sizes are small, and the reason they do not account for the full enrollment is not reported. Readers can describe the observed measurements, but cannot use the registry result to establish the precision or statistical significance of an arm difference.
The pilot framing also matters. A pilot can provide descriptive information relevant to planning future research, but the registry does not report the study’s own sample-size justification or a detailed analysis plan. Its planning illustration is explicitly based on the observed effect and specified assumptions; it should not be interpreted as observed power or as proof that the study was adequately sized for a confirmatory question.
Finally, the registry lists several secondary cardiac measures alongside the capture-threshold endpoint. Distinguishing the primary electrical measure from these other outcomes helps prevent a narrow result from being read as a conclusion about broader heart function or clinical outcomes. The record’s incomplete reporting of analyses, missing-data handling, and outcome populations limits the statistical conclusions that can be drawn.
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 overall enrollment is 9, while the posted primary outcome summaries include 3 participants in the His Bundle Pacing arm and 5 in the Left Bundle Area Pacing arm. The registry does not explain the difference. Without participant flow, measurement availability, or analysis-population details, it is unclear why the primary summaries do not account for the recorded enrollment.
The result is reported as arm-level means and standard deviations only. No confidence interval, standard error, p-value, or primary comparison analysis is reported. This prevents assessment of the precision of the arm contrast. The record also does not report individual observations, so the distribution of the measurements and the influence of individual values cannot be evaluated.
The registry does not report the protocol’s sample-size justification, a detailed statistical analysis plan, missing-data methods, or any interim analyses. It does not explain why the study was terminated or whether termination affected data collection or follow-up. The record lists 21 secondary outcomes as posted but does not describe their analyses or a method for addressing multiplicity.
Safety risk-set counts differ from the primary outcome sample counts, and the reason is not reported. The safety reporting also lacks further detail on event definitions and observation period. Finally, the primary endpoint concerns capture threshold at 3 months; the posted summary does not establish effects on battery life, longer-term cardiac function, or other clinical outcomes.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Left Bundle Area Versus Selective His Bundle Pacing — NCT04093414.
- Registry record last updated 2022-08-17; status last verified 2022-06.
- Results first posted 2022-08-17.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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19. Record Summary
The registry describes LEFTBASH as a single-center, open-label, randomized pilot study with a parallel design and no masking. It lists enrollment of 9 and status TERMINATED. The recorded start date is 2019-10-07, and the primary completion date is 2022-02-14. The reason for termination is not reported in the registry record.
The comparison is Selective or Non Selective His Bundle Pacing versus Left Bundle Area Pacing. The primary outcome is ventricular capture threshold at 3 months, measured in volts and summarized as a mean with standard deviation. The reported arm summaries are 0.66 volts with standard deviation 0.14 for 3 participants and 0.65 volts with standard deviation 0.13 for 5 participants. No primary analysis, confidence interval, or p-value is reported.
The registry lists 22 outcome measures, including 21 secondary outcomes as posted. It records 0 analyses. Missing-data methods, analysis populations, the study’s sample-size justification, and the reason for the difference between enrollment and the primary outcome counts are not reported in the registry record.