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 Genetically Determined Response to Atenolol in Patients With Persistent Atrial Fibrillation (NCT01719367), a na na study. The primary outcome is Change in Pre- and Post-atenolol Ventricular Rate Response After 5 Minutes of Exercise.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01719367 |
| Phase | NA |
| Condition | Atrial Fibrillation |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 38 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Vanderbilt University Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
Patients with persistent atrial fibrillation are the population named in the study title. The registry record does not report detailed eligibility criteria or participant characteristics.
Intervention
Participants received a single dose of oral atenolol after a baseline exercise protocol. The dose is not reported in the registry record.
Comparator
Each participant’s exercise heart-rate response before atenolol was compared with the response after atenolol. The study is recorded as single group, with no randomized control group.
Primary question
How did ventricular rate response after 5 minutes of exercise change between the pre-atenolol and post-atenolol assessments, and how did that change vary among patients with different genetic polymorphisms?
The study focuses on individual variation in response rather than a randomized comparison of atenolol with another treatment or with no treatment. Participants completed a standardized exercise protocol before receiving atenolol and repeated it after a waiting period intended to allow for peak drug effect. The registry describes a modified Bruce protocol and asks participants to exercise to sub-maximal exertion.
The primary question therefore has two linked parts: the within-participant change in ventricular rate response following atenolol, and whether that change differs across genetic polymorphisms thought to have a role in response. The registry record does not identify the polymorphisms, state how many were examined, or report the results of those comparisons. It also does not report a numerical primary outcome estimate. The clinical question can be described from the protocol, but the posted record does not allow the size or precision of the response to be assessed.
3. Trial Design
The registry identifies this as a completed, single-group study sponsored by Vanderbilt University Medical Center. Enrollment was 38. The recorded start was 2013-01, and primary completion was 2016-09. The phase is listed as NA, allocation as NA, and masking as none. The record does not describe a randomized treatment assignment or a separate control group.
The protocol description uses a repeated-measures approach. Participants first had baseline vital signs and an ECG recorded, then completed a standardized modified Bruce exercise protocol. Heart rate was recorded during each exercise stage, with exercise continuing to sub-maximal exertion. Participants then received a single oral dose of atenolol and waited two hours before repeating the protocol. The primary outcome was the difference between the pre- and post-atenolol ventricular rate response to exercise.
The registry describes comparisons among patients with different polymorphisms in genes that might affect response to atenolol. These genetic groupings are not a randomized treatment comparison: genetic status is used to examine variation in response among people receiving the same intervention. The record does not report the genetic variants, the rules used to assign participants to genetic groups, or the statistical approach for comparing those groups.
Two outcome measures are listed, but the details and results for the other measure are not reported in the registry record. The study is marked completed, but completion status alone does not provide an estimate of the primary outcome. Sample-size justification, the intended analysis population, and a full 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.
Overall Study
| Stage | Atenolol: Ancestral Alleles | Atenolol: Variant Carriers |
|---|---|---|
| STARTED | 19 | 19 |
| COMPLETED | 19 | 19 |
| 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.
Population: The PI of this study left Vanderbilt. Limited data are available for this study. Baseline data are not available per-arm, therefore, only the baseline data for overall population is being reported.
| Characteristic | Unit | All Participants |
|---|---|---|
| Participants analysed | 38 | |
| Age, Continuous | years | 70.5 (60 to 74.8) |
| Sex: Female, Male: Female | Participants | 4 |
| Sex: Female, Male: Male | Participants | 34 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 38 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 19 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Pre- and Post-atenolol Ventricular Rate Response After 5 Minutes of Exercise, measured over after 5minutes of exercise.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | beats per minute |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the change in ventricular rate response to exercise between the assessment before atenolol and the assessment after atenolol. The registry names the outcome as a mean, gives beats per minute as its unit, and specifies a 95% confidence interval as its dispersion measure. Its stated timeframe is after 5 minutes of exercise. The protocol describes recording heart rate during each exercise stage before and after the dose.
This endpoint is intended to capture the heart-rate response under a standardized physical challenge, rather than only a resting measurement. Comparing the two assessments within a participant makes each participant’s pre-dose response the reference for their post-dose response. The registry further proposes comparing these changes among patients with different genetic polymorphisms, addressing whether response varies across genetic groups.
General statistical context: a mean describes the average outcome in a group, while a confidence interval conveys uncertainty around an estimate under the statistical model used. The interval’s width depends on factors including the amount of variability and the amount of information available. The registry names the confidence interval format but does not post the primary mean change or its interval. Consequently, neither the estimated size of the change nor its precision can be evaluated from the reported outcome information.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a within-participant comparison of exercise heart-rate response before and after a single dose of atenolol, with planned comparisons by genetic polymorphism. However, it does not report the primary outcome estimate, its 95% confidence interval, or results for the genetic comparisons. The direction, size, and precision of the measured change are therefore not reported in the registry record.
This distinction matters because a protocol and a result answer different questions. The protocol explains what investigators intended to measure and when. A numerical estimate would describe the observed change, while its confidence interval would show the uncertainty around that estimate. Without those results, the registry entry cannot establish whether responses were similar or different across genetic groups, or how substantial any observed change was.
The enrollment was 38, but that count alone does not indicate the precision of a mean change or of comparisons among genetic groups. Precision depends on the outcome’s variability, the distribution of participants across groups, and the analysis. Those details and estimates are not reported in the registry record. The safety entries list 19 participants at risk in each of the ancestral-allele and variant-carrier categories, but those figures do not supply the missing primary outcome results.
General statistical context: a confidence interval is not a guarantee that an estimate is correct. It describes uncertainty under assumptions of the analysis, and its interpretation depends on the validity of the design, measurements, and model. For a pre/post study, the paired structure is important because each participant contributes both measurements. A comparison that ignores that pairing may not represent the intended analysis. The registry record does not report the analysis used, so it is not possible to assess whether the posted method accounted for the repeated measurements.
The record’s completed status indicates that the study is no longer listed as ongoing, but it does not substitute for outcome reporting. Nor does an absent result imply that the intervention had no effect. The defensible reading is narrower: the registry describes the measurement plan and enrollment, while the primary findings and their uncertainty are not reported in the registry record.
9. Statistical Methods Explained
General statistical context: The protocol’s central comparison is paired: heart-rate response is measured in the same participant before and after atenolol. Pairing can be useful because stable differences between participants are present in both measurements. The analysis can focus on each participant’s change rather than treating the two sets of measurements as unrelated. The registry describes a difference as the primary outcome but does not report the calculation details or the statistical model used.
What does a mean change describe?
General statistical context: A mean change is the average of the participant-level changes under the definition used by the study. It condenses a set of individual responses into one summary, but it does not show how much responses differ from person to person. Two groups can have the same mean change while having different distributions of individual responses. The registry identifies a mean outcome in beats per minute, but does not post its value or a measure of individual variability.
How should a confidence interval be understood?
General statistical context: A confidence interval gives a range of estimates compatible with the observed data and the method’s assumptions. A narrower interval generally indicates greater precision than a wider interval, but precision is not the same as clinical importance. An interval also does not resolve design limitations, measurement error, or bias. The registry specifies a 95% confidence interval for the primary outcome, but its endpoints are not reported in the registry record. The interval’s width and the range of changes compatible with the data therefore cannot be assessed.
Why examine genetic groups?
The stated scientific aim is to compare the primary outcome among patients with different polymorphisms in genes that might play a role in individual response to atenolol. General statistical context: Such analyses evaluate whether the outcome appears to vary across subgroups. They require the group definitions, the number of participants in each group, the estimated changes, and the method used to compare them. Small or uneven groups can make subgroup estimates imprecise. The registry does not identify the variants or report group-specific results, so no conclusion about differences by genotype can be drawn from this record.
What does the study design allow?
The recorded design is single group, and the masking entry is none. Each participant’s baseline exercise response serves as a pre-dose reference; there is no randomized parallel control group in the registry record. General statistical context: A paired pre/post comparison can describe changes over the measurement period, but by itself it cannot separate the intervention’s contribution from other influences that change between assessments. Standardizing the exercise protocol and timing can support consistent measurement, but the registry does not report adherence, deviations, or other procedural details.
What can the enrollment count tell us?
The recorded enrollment is 38. That is a study size, not an outcome estimate. General statistical context: Sample-size planning depends on the outcome variability, the effect the investigators aim to detect, the chosen error rates, and the planned analysis. The registry record does not report the trial’s own sample-size justification. Any planning illustration based on an observed effect should not be confused with observed power, and planning assumptions do not establish how precise the actual result is. Since the primary estimate is not reported, its observed precision cannot be judged.
What role does the measurement schedule play?
The protocol places the second exercise test after a two-hour wait intended to allow for peak atenolol effect. General statistical context: Timing helps define what the endpoint represents. A response at the specified assessment time need not describe responses at other times or under other conditions. The stated endpoint is tied to exercise, and the record does not report a resting-rate primary outcome. It also does not report numerical heart-rate measurements at individual stages, so the trajectory across the exercise protocol cannot be assessed.
Overall, the design and outcome definition describe how the investigators intended to measure response. They do not supply the estimates needed to quantify response or evaluate genetic variation. Statistical interpretation requires the posted results together with the analysis details; these are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures and identifies the exercise-related change as the primary outcome. It lists zero analyses. The record does not report the results for the primary endpoint or the other outcome measure, nor does it describe a statistical analysis plan, a multiplicity adjustment, or a hierarchy for interpreting multiple outcomes.
The planned genetic comparisons raise an additional multiplicity consideration. The registry states that the primary measure will be compared among patients with various polymorphisms, but does not report how many variants or comparisons were planned. General statistical context: when many hypotheses are tested, the chance of at least one apparently notable finding can increase. Methods for controlling or describing this issue depend on the analysis plan and the number and structure of the comparisons. Since those details are not reported in the registry record, the extent to which multiplicity was addressed cannot be assessed.
Missing-data handling and the analysis population are also not reported in the registry record. It is not stated whether all enrolled participants completed both exercise tests, how incomplete measurements would be handled, or whether any participants were excluded from an analysis. These details affect which participants contribute to an estimate and can influence its interpretation.
The sample-size justification and any interim analyses are not reported in the registry record. Their absence from the entry does not establish what may have been planned or conducted; it means those methods cannot be evaluated from the posted information. The outcome results and analysis details would be needed to assess robustness, precision, and the handling of multiple comparisons.
11. 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 |
|---|---|---|---|
| Atenolol: Ancestral Alleles | 0 | 19 | 0.0% |
| Atenolol: Variant Carriers | 0 | 19 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Atenolol: Ancestral Alleles | 0 of 19 |
| Atenolol: Variant Carriers | 0 of 19 |
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 |
|---|---|
| Atenolol: Ancestral Alleles | 0 of 19 |
| Atenolol: Variant Carriers | 0 of 19 |
The serious-adverse-event entries distinguish ancestral-allele participants from variant carriers. Each category lists 19 participants at risk, 0 serious events, 0 other events, and 0 deaths. These are the safety figures recorded for the two categories.
These counts describe what is entered in the registry record; they do not by themselves establish that no adverse events occurred outside the reporting categories or observation period. The record does not report the safety follow-up duration, event definitions, ascertainment procedures, or a narrative explanation of the entries. It also does not provide a comparison with an untreated or randomized control group.
General statistical context: zero events in a group means no events were recorded in that group’s reported count. It does not prove that the underlying risk is zero. The ability to characterize uncommon events depends on the number of people observed and the duration and completeness of follow-up. The posted figures should therefore be read as reported counts, not as a definitive estimate of safety across a broader population.
12. What the Result Does, and Does Not, Mean
The registry record establishes that investigators planned to measure exercise-related ventricular rate response before and after a single oral dose of atenolol and to compare changes across genetic polymorphisms. It also records enrollment of 38 and marks the study completed. The record does not report the primary outcome estimate, its confidence interval, or the genetic subgroup results. It therefore does not permit a quantitative conclusion about the observed response or its variation by genotype.
This absence should not be read as evidence that there was no change, that groups responded identically, or that a particular genetic pattern was associated with response. Those conclusions require numerical results and analysis details. The recorded safety counts likewise describe only the entries made for the two categories; they do not replace a full account of adverse-event definitions and follow-up.
General statistical context: a study can be informative in its design even when the registry entry does not provide its findings. The protocol identifies a repeated exercise measurement and a question about genetic heterogeneity. To judge the evidence, readers would need the magnitude of the within-participant changes, uncertainty around those changes, subgroup estimates, participant flow, and the methods used to handle missing data and multiple comparisons. These are not reported in the registry record.
The title and protocol frame the population as patients with persistent atrial fibrillation, but detailed eligibility criteria and participant characteristics are not reported. The record thus also gives limited information about how closely the enrolled participants represent other groups. The most supportable interpretation is that the registry describes the intended study question and design, while the posted information is insufficient to assess the primary findings or their precision.
13. Why This Trial Matters Statistically
The study addresses a statistical question about response heterogeneity: whether the change in exercise heart-rate response following atenolol varies among patients with different genetic polymorphisms. This differs from asking only whether the average response changed. A single overall mean can conceal variation among individuals, while subgroup analysis seeks to describe whether some genetic categories have different patterns.
The repeated pre/post measurements are central to the design. Comparing each participant with their own baseline can account for stable differences between people, provided the analysis respects the paired structure. The protocol also standardizes the exercise procedure and sets a two-hour wait before the post-dose test. These features define the measurement context, although the registry does not report how consistently the protocol was completed.
The trial is statistically notable for the gap between a clear outcome concept and the absence of posted estimates. The registry specifies a mean change and a 95% confidence interval, but does not report either. Without them, readers cannot judge the scale of the result or its precision. The lack of genetic group results further limits interpretation of the study’s central heterogeneity question.
General statistical context: subgroup findings can be particularly sensitive to small group sizes and multiple testing. The overall enrollment was 38, but the distribution across genetic categories and the number of variants are not reported. The record therefore does not allow an assessment of whether the genetic comparisons were adequately precise or how they were protected against chance findings.
The value of the study’s statistical question is clear from its design, but the strength of evidence cannot be determined from the registry entry alone. Outcome estimates, analysis methods, and details of participant inclusion would be needed to evaluate the findings.
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 outcome result, its 95% confidence interval, or the genetic comparison results. The mean change and its precision cannot be assessed. Although the study is marked completed, completion status does not establish that results are available in this record.
The entry gives limited information about the population. It names persistent atrial fibrillation in the title and lists atrial fibrillation as a condition, but detailed eligibility criteria and participant characteristics are not reported in the registry record. The atenolol dose is also not reported. The specific genes and polymorphisms, group definitions, and group sizes are not reported, preventing assessment of the genetic comparisons.
The recorded design is single group with no masking and no randomized control group. The pre/post measurements support a within-participant comparison, but the registry entry does not report the analysis method, participant flow, protocol deviations, or handling of missing observations. It is therefore not possible to evaluate the completeness of paired data or whether the analysis matched the repeated-measures design.
The registry does not report the study’s sample-size justification, interim analyses, multiplicity procedures, or analysis populations. The safety entries give counts, but follow-up duration and event definitions are not reported. These limitations concern what can be evaluated from the registry record; they do not establish what procedures were or were not used outside the record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Genetically Determined Response to Atenolol in Patients With Persistent Atrial Fibrillation — NCT01719367.
- Registry record last updated 2019-06-17; status last verified 2019-06.
- Results first posted 2019-06-17.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
This completed, single-group study enrolled 38 participants and examined exercise-related ventricular rate response before and after a single oral dose of atenolol. The protocol describes a standardized modified Bruce exercise test, a two-hour wait after dosing, and a repeat test. Its primary question concerns pre/post change and variation across genetic polymorphisms.
The registry lists a mean outcome in beats per minute with a 95% confidence interval, but the numerical primary result and genetic comparison findings are not reported in the registry record. Detailed eligibility criteria, the atenolol dose, genetic variants, analysis methods, missing-data procedures, and the study’s sample-size justification are also not reported. The safety entries list 19 participants at risk in each genetic category, with 0 serious events, 0 other events, and 0 deaths in each. The posted information describes the planned question and selected registry entries, but is insufficient to assess the primary result or its precision.