Master Study for the Investigation of Safety and Efficacy of the EVIA Pacemaker: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Master Study for the Investigation of Safety and Efficacy of the EVIA Pacemaker (NCT00916344), a non-randomized na study. The primary outcome is Efficacy of Atrial Capture Control Feature (Automatic Atrial Threshold Test Minus Manual Atrial Measurement).

2. Clinical Question

This question focuses on the device’s measurement and adjustment feature rather than on a comparison of two assigned treatment strategies. Automatic and manual threshold tests are both named in the endpoint, and the described primary population includes patients who had both. The direction of the difference is defined as automatic minus manual, so its sign would indicate which measurement is larger if a numerical result were reported. Without that estimate, the registry record cannot establish the observed direction or size of the difference.

The stated study objective also includes safety and efficacy of the EVIA pacemaker, with the Atrial Capture Control algorithm as the primary focus. A complication-free rate is listed as a secondary outcome. The record does not give the secondary outcome result or define its calculation in the information available for this analysis.

3. Trial Design

The registry lists this as a completed, non-randomized, single-group device study with no masking. The intervention is the EVIA pacemaker, and the arm description identifies pacemaker therapy. There is no randomized control group described. In particular, the primary comparison is not between two arms: it is between automatic and manual measurements made in patients who had both tests.

The study enrolled 175 participants. The recorded start is 2009-06, and primary completion is recorded as 2010-02. The phase is listed as NA. The condition is pacemaker indication, and the sponsor is Biotronik SE & Co. KG. These registry entries describe the study record; they do not, by themselves, show how many enrolled participants contributed to each endpoint or how follow-up was handled.

The stated objective is to evaluate safety and efficacy of the EVIA pacemaker, primarily assessing the newly implemented Atrial Capture Control algorithm. The algorithm automatically measures the right atrial threshold and subsequently adjusts pacing output. For the primary endpoint, the record specifies a one-month follow-up and identifies 93 patients with a dual-chamber pacemaker who had both manual and automatic atrial threshold tests. It labels this as an ITT analysis, but does not explain how the ITT population was defined or reconciled with the requirement for both test measurements.

Because the design is single-group and non-randomized, the study does not supply a randomized between-group estimate of the effect of pacemaker therapy versus an alternative. Its primary endpoint instead uses a paired measurement comparison. That distinction matters when interpreting both the endpoint and the safety summaries: neither should be read as a randomized treatment contrast. The record does not report a detailed protocol, a sample-size justification, an interim-analysis plan, or a fuller account of the follow-up schedule.

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: At 1 month follow-up 93 patients with dual chamber pacemaker had both manual and automatic atrial treshold tests (ITT analysis).

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 Efficacy of Atrial Capture Control Feature (Automatic Atrial Threshold Test Minus Manual Atrial Measurement), measured over 1 month follow-up completed.

The primary endpoint is titled as the efficacy of the Atrial Capture Control feature and is defined as the automatic atrial threshold test minus the manual atrial measurement. It is a continuous measure, reported in Volt, with the mean identified as the summary statistic and a 95% confidence interval as the stated measure of precision. The specified timeframe is completion of one-month follow-up.

The feature is intended to measure the atrial pacing threshold automatically and then adjust atrial pulse amplitude. Comparing automatic and manual threshold measurements therefore addresses how the automated assessment relates to the manual measurement in the same patients. A difference near zero would describe similar average measurements; a difference away from zero would describe an average separation, with direction determined by the stated subtraction order. These are general interpretations of a signed difference, not conclusions about this study: the numerical estimate is not reported in the registry record.

A mean is useful for describing the average paired difference, while the confidence interval conveys uncertainty about that estimate. Because both types of measurement were available for the endpoint population, a paired analysis would account for the within-patient relationship between measurements. That is a general statistical rationale, not confirmation of the exact analysis used. The registry record does not report the observed mean difference, the confidence limits, a test statistic, or a p-value.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is a continuous paired measurement: automatic atrial threshold test minus manual atrial measurement. The registry specifies a mean and a 95% confidence interval, but does not report the estimate, the interval, or a detailed statistical analysis plan. The explanations below describe general statistical concepts relevant to this type of endpoint; they should not be read as a description of unreported methods used in the study.

Why does the paired structure matter?

When two measurements are taken from the same patient, they are usually related: characteristics that influence one measurement may also influence the other. A paired analysis works with the within-patient differences rather than treating the two sets of measurements as if they came from unrelated groups. This can account for the fact that each patient serves as their own measurement comparator. The endpoint’s subtraction order is automatic minus manual, which defines the direction of any reported difference.

The record describes 93 patients who had both tests. That wording is consistent with a paired endpoint population, but the registry does not state the specific calculation used to obtain the mean difference. It does not say whether the analysis used a paired t procedure, a model, or another method. It would therefore be inappropriate to identify a particular inferential procedure as the one performed.

What does the mean difference describe?

A mean difference is the average of the patient-level differences on the stated measurement scale. It provides a summary of the average separation between automatic and manual measurements. The unit is Volt, and the direction is set by automatic minus manual. A mean alone does not describe the full spread of individual differences: patients can differ from the average, and a similar average can arise from different patterns of individual results.

For paired data, the variability of the differences is important. The relationship between the two measurements affects the variability of their difference. A paired approach retains that relationship; an unpaired analysis would discard it. This is a general reason to match the analysis to the data structure, not evidence that any particular method was used for this endpoint.

How should a confidence interval be read?

A confidence interval expresses uncertainty around an estimated quantity under the analysis assumptions. In repeated use of the same method under its assumptions, confidence intervals would capture the underlying quantity at the stated rate. In practical interpretation, the interval conveys both the estimated direction and how precisely the estimate is determined. A narrow interval suggests more precision than a wide interval. The registry specifies a 95% confidence interval, but gives no limits, so neither its width nor its position relative to zero can be assessed.

The interval and point estimate would need to be considered together. A small estimated difference with a wide interval can leave substantial uncertainty; a more precise estimate can still require interpretation in relation to the measurement’s clinical context. The registry record does not state a threshold for a meaningful difference, so no clinical-importance boundary can be applied from the recorded details.

What can be inferred from the sample-size assumptions?

The stated sample-size convention is a planning illustration based on the observed effect, not the trial’s own design. It uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event outcomes, the convention specifies total events, while other outcomes use participants per arm. These are general planning assumptions and are not a record of the single-group study’s actual design.

The primary endpoint is a paired continuous comparison in a single-group study, whereas the planning convention describes equal allocation between two arms. That makes the illustration hypothetical rather than a direct description of the trial structure. No numerical sample-size illustration is included in the registry entries, and the observed primary effect is also not reported. The resulting planning values therefore cannot be interpreted from the registry record. Such illustrations are not observed power and do not establish what the original study was designed to detect.

Why do analysis details matter?

Statistical interpretation depends on more than naming a mean and confidence interval. It also depends on how the analysis population was defined, how missing paired measurements were handled, whether assumptions were checked, and whether the analysis followed a prespecified plan. The registry lists zero analyses and does not report these details. No assumptions about normality, outliers, adjustment, or interim monitoring can be made from that absence.

Continuous paired differences may be analyzed using methods that rely on distributional assumptions, or methods that make different assumptions. The choice can affect estimates of uncertainty and resulting intervals. If differences are unusually skewed or contain influential observations, the mean and its interval may be sensitive to those features. These are general considerations. The record does not provide the patient-level data or diagnostic information needed to assess them.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and identifies the complication-free rate as a secondary outcome. It records zero analyses. The registry entries do not describe a multiplicity strategy, such as a prespecified hierarchy among outcomes or an adjustment to account for testing more than one outcome. Whether any multiplicity adjustment was planned or used is not reported in the registry record.

Multiplicity matters when several outcomes or hypotheses are evaluated: examining more results can increase the chance of at least one apparently notable result by chance. This is a general statistical concern, not a claim that such a result occurred in this study. With no reported analyses or outcome estimates, the effect of any multiplicity approach cannot be assessed.

For the primary endpoint, the registry identifies 93 patients who had both threshold tests at one-month follow-up and labels the analysis ITT. It does not explain how the analysis population was defined, how many enrolled patients lacked one or both measurements, why measurements may have been unavailable, or what method was used to address missing data. No missing-data method, imputation strategy, or sensitivity analysis is reported in the registry record.

Requiring both measurements for the stated paired comparison means that patients without a complete pair cannot contribute a directly observed within-patient difference. This is a general feature of paired measurement analysis. How excluding or otherwise handling incomplete pairs could affect the result depends on why data are missing and on the analysis choices; those details are not reported. The ITT label alone does not resolve those questions.

The record also does not describe interim analyses, the statistical plan, or a sample-size justification. It is therefore not possible to assess whether outcome selection, missing-data handling, and hypothesis testing followed a prespecified plan.

11. 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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: lead dislocation (5.7%), cardiac decompensation (2.9%), pocket haematoma (2.3%), spinal disease (2.3%), atrial fibrillation / flutter related (1.7%).

For the pacemaker therapy group, the registry records 175 at risk for serious adverse events and 52 affected. It separately records 175 at risk for other adverse events and 28 affected. These are descriptive safety figures from a single-group study, not a contrast with a randomized control group. The registry does not provide a comparative estimate of risk.

The serious adverse-event terms listed with percentages are lead dislocation, 5.7%; cardiac decompensation, 2.9%; pocket haematoma, 2.3%; spinal disease, 2.3%; Atrial fibrillation / flutter related, 1.7%; and chest pain, 1.7%. These listed terms describe reported categories. They should not be added together: the registry record does not establish whether categories overlap or whether a patient could have more than one event.

The figures do not, on their own, show how events were adjudicated, their timing, their duration, or their relationship to the device. Those details are not reported in the registry record. A death count is also not reported in the registry record. Because there is no control group, the safety summaries cannot determine how these observations compare with another treatment or with an untreated group.

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

The record identifies a specific measurement question: how the automatic atrial threshold test compares with a manual measurement in patients who had both at one-month follow-up. It also describes the feature’s purpose: automatic threshold measurement followed by adjustment of pacing output. These details clarify what the primary endpoint was intended to assess.

What the record does not provide is the numerical primary endpoint result. The mean difference and its confidence limits are not reported in the registry record. As a result, the observed direction and size of the difference, and the precision of the estimate, cannot be evaluated. The endpoint title and objective are not substitutes for an observed result, and they do not establish that the automatic and manual measurements were similar or different.

The design also sets limits on interpretation. This was a non-randomized, single-group study without masking. Its primary comparison is within-patient, not a comparison of randomized groups. The study therefore does not provide a randomized estimate of how pacemaker therapy compares with an alternative treatment. The safety summaries likewise describe the recorded group and cannot establish a comparative safety effect.

The registry’s ITT label for the primary population does not resolve how the analysis handled participants without both measurements. The record does not state the missing-data approach, endpoint analysis method, multiplicity strategy, or detailed statistical plan. These gaps limit assessment of potential bias and of how robust any result might be, even if a numerical estimate were available.

The appropriate statistical reading is therefore bounded: the registry describes the study design, endpoint definition, one-month paired-test population, and selected safety counts and terms. It does not report enough primary outcome information to judge the observed measurement difference. These registry entries do not establish clinical benefit, lack of benefit, or a comparative safety conclusion.

13. Why This Trial Matters Statistically

This study is statistically notable for using a paired measurement question within a single-group device study. The automatic and manual atrial threshold tests are intended to be compared in the same patients, which makes the within-patient difference central to the endpoint. Recognizing this structure is important: it is distinct from comparing independent treatment groups, and it calls for an interpretation focused on paired differences.

The endpoint also illustrates why a result needs both an estimate and a measure of precision. A defined mean difference and a stated 95% confidence interval tell readers what the investigators intended to summarize, but without the numerical estimate and interval, the central statistical question remains unanswered in the registry record. The endpoint definition alone cannot reveal the size, direction, or precision of the observed difference.

The registry’s description of 93 patients with both measurements alongside an ITT label raises a separate reporting issue. A clear account of the analysis population and missing paired measurements helps readers judge how the endpoint relates to enrollment and whether the analysis may be affected by data availability. That explanation is not reported in the registry record.

Finally, the single-group design places the safety data in context. Event counts and listed terms can describe what was recorded among the pacemaker therapy group, but they cannot provide a randomized comparison. Separating descriptive safety summaries from comparative evidence is essential to avoid attributing differences that the design cannot estimate. The record’s value is in its specification of the study question and design; its limitations arise from absent primary results and unreported analysis details.

14. Limitations

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

The primary limitation for interpretation is that the registry record does not report the numerical primary endpoint result. Although the endpoint’s scale, direction, summary statistic, confidence interval type, timeframe, and described population are specified, there is no mean difference or confidence interval to interpret. The record therefore does not show the observed effect or its precision.

The study is non-randomized, single-group, and unmasked. Its primary endpoint is a paired automatic-versus-manual measurement comparison, not a randomized treatment comparison. These design features limit conclusions about comparative effects of the device or about how safety outcomes differ from those under another treatment. No control group is described.

The record identifies 93 patients with both tests and labels this an ITT analysis, but does not explain the relationship between this population and the 175 enrolled participants. The reasons for absent or incomplete measurements, the handling of missing data, and the exact analysis population are not reported. It is not possible to quantify missingness from the stated information without deriving an unreported figure, and no such estimate is appropriate.

Further limitations include the absence of a detailed statistical plan, a sample-size justification, an account of interim analyses, and an explanation of multiplicity handling. The registry records zero analyses, and it does not provide the primary or secondary outcome estimates. For safety, event categories may overlap, and details about timing, adjudication, and relationship to the device are not reported. These gaps constrain assessment of both the efficacy endpoint and safety summaries.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Master Study for the Investigation of Safety and Efficacy of the EVIA Pacemaker — NCT00916344.
• Registry record last updated 2011-10-07; status last verified 2011-10.
• Results first posted 2011-09-30.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry describes a completed, non-randomized, single-group study of the EVIA pacemaker, with no masking and 175 participants enrolled. Its primary objective focused on the Atrial Capture Control feature. The primary endpoint compares automatic and manual atrial threshold measurements as automatic minus manual, in Volt, using a mean and a 95% confidence interval at one-month follow-up.

The endpoint population is described as 93 patients with a dual-chamber pacemaker who had both tests, and is labeled ITT. The numerical primary result, its confidence interval, the complication-free-rate result, and detailed analysis methods are not reported in the registry record. Safety data list serious and other adverse-event counts and several serious adverse-event terms, but the single-group design does not provide a randomized safety comparison.