Pathogenesis of Stress-Induced Cardiomyopathy by I-123 MIBG: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pathogenesis of Stress-Induced Cardiomyopathy by I-123 MIBG (NCT01432626), a na na study. The primary outcome is Number of Participants Who Had an Abnormal Regional Uptake of I-123 mIBG at Baseline (Acute Phase) and the Number of Participants Who Had an Abnormal I-123 mIBG Uptake on Follow up (Recovery Phase).

2. Clinical Question

3. Trial Design

This was a prospective pilot study of cardiac sympathetic innervation in patients presenting with stress-induced, or Takotsubo's, cardiomyopathy. The University of Pittsburgh is listed as the sponsor. The registry record lists the study as completed, with a start date of 2011-09 and a primary completion date of 2014-12. Enrollment is listed as 10.

The design is recorded as single-group, with allocation listed as NA and masking listed as none. There was no randomized comparison and no like-for-like control arm. The imaging intervention was I-123 radiolabeled metaiodobenzylguanidine cardiac imaging, using planar and SPECT imaging. The study description says imaging was planned in the acute presentation and after recovery of left ventricular function.

The acute assessment was scheduled during the acute phase, described as 2-5 days, with an expected mean of 3 days. Follow-up was scheduled after recovery of cardiac function at 6 weeks. The registry record does not state how many participants completed each imaging assessment, whether all participants had both assessments, or whether the timing was achieved for each participant.

The primary outcome is a count of participants with abnormal regional uptake at the acute assessment and a count with abnormal uptake at follow-up. No participant counts for either time point are reported in the registry record. The record lists one outcome measure and no statistical analyses. The phase is listed as NA. A sample-size justification for the pilot itself is 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

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 Number of Participants Who Had an Abnormal Regional Uptake of I-123 mIBG at Baseline (Acute Phase) and the Number of Participants Who Had an Abnormal I-123 mIBG Uptake on Follow up (Recovery Phase), measured over During the acute phase (2-5 days with an expected mean 3 days) and after recovery of cardiac function (6 weeks).

The primary endpoint asks for the number of participants with abnormal regional uptake of I-123 mIBG at two scheduled stages: the acute phase and follow-up after recovery of cardiac function. The acute assessment was planned for 2-5 days, with an expected mean of 3 days, and follow-up was planned at 6 weeks. The endpoint is expressed as a count of participants, rather than as a continuous imaging measurement.

This outcome was selected to describe the imaging pattern associated with stress-induced cardiomyopathy and to examine whether abnormal uptake was present during the acute presentation and at recovery. The study description frames the imaging as a way to investigate possible perturbations in cardiac sympathetic innervation and to inform understanding of the condition's pathogenesis. Those are research aims, not findings established by the endpoint definition.

The registry record does not report the observed counts, define the threshold or reading rule used to classify uptake as abnormal, or explain how a regional imaging finding was translated into a participant-level classification. It also does not report the number of participants with evaluable scans at each time point. Without those details and the outcome counts, the endpoint's observed frequency or change over time cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design imply?

In general, a single-group study describes observations among participants who share the study's condition and receive the specified assessment or intervention. It does not create a randomized control group. In this study, the planned acute and recovery assessments offer two observations over time, but they are not a comparison between randomized arms. The record lists allocation as NA and masking as none. It does not report a statistical model or test for comparing the time points.

When the same participants are assessed repeatedly, the observations may be related: a participant's finding at one assessment can be connected to that participant's finding at another. General statistical methods for repeated observations account for this relationship when estimating change or uncertainty. The registry record does not say whether both scans were obtained for each participant or how any paired observations were analyzed. Therefore, a particular repeated-measures method should not be attributed to the study.

How should a count endpoint be read?

In general, a count of participants with an event states how many people met a defined outcome. It is distinct from a proportion, which also requires the number assessed, and from a rate, which requires a time basis. The primary outcome is a participant count for abnormal regional uptake at each assessment. The record does not report the counts or the number assessed at either time point. Enrollment is not a substitute for those endpoint-specific denominators, because the registry record does not say that every enrolled participant contributed a result at both assessments.

The classification rule matters for a binary outcome. In general, readers need to know how an image was judged abnormal, whether interpretation followed a prespecified threshold, and how inconclusive or technically inadequate images were treated. The registry description identifies abnormal regional uptake as the outcome, but does not report those operational details, reader procedures, or reproducibility measures. This limits the ability to understand how consistently the outcome could be applied.

What can uncertainty estimates tell readers?

In general, a confidence interval communicates the range of values compatible with an estimate under the statistical method and assumptions used. For a count or proportion, its interpretation depends on the number of observations and on the analysis method. A narrow interval generally indicates greater precision than a wide interval, while an interval does not by itself establish clinical importance or prove a cause-and-effect relationship. The registry record does not report an estimate or confidence interval for the primary outcome, and it lists no statistical analyses. Thus, the precision of the study's imaging findings cannot be evaluated from the posted results.

For a repeated binary outcome, a general analysis could describe each assessment separately and, if the same participants contributed both results, examine changes within participants. Such an analysis needs information about the paired classifications, not just separate counts. The registry record does not provide those paired data or state that such an analysis was performed. No test, model, adjustment, or uncertainty method should be assumed.

What do the planning illustrations represent?

The registry record describes sample-size planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect, and that the non-time-to-event illustrations are expressed as participants per arm. These are planning assumptions, not a report of the study's own design justification or observed power. The trial itself is recorded as single-group, without a randomized two-arm comparison, and the observed primary outcome counts and effect are not reported in the registry record. The record does not report the pilot's sample-size justification.

In general, sample-size planning asks how much information a future study might need under specified assumptions. A planning illustration cannot establish that a completed study had a particular probability of detecting an effect, and it is not a substitute for an uncertainty interval around an observed estimate. The record does not report the calculations' resulting sample sizes in the study description, so no such values can be stated.

What is not documented about the analysis?

The registry record lists one outcome measure and no statistical analyses. It does not report a statistical analysis plan, a prespecified method for handling repeated measurements, or inferential results for the primary endpoint. It also does not report how missing imaging or incomplete follow-up was handled. These are absences in the registry record, not evidence that a particular method was or was not used outside the record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure, but does not report a multiplicity strategy. Multiplicity concerns arise when several outcomes, time points, subgroups, or statistical tests are examined and findings are interpreted together. The primary outcome description includes acute and recovery assessments, but the record does not explain whether these were treated as separate tests, as a paired comparison, or only as descriptive counts. No adjustment method or hierarchy of analyses is reported.

There are no listed statistical analyses. The record does not describe an analysis population, such as which participants were included in the primary outcome assessment, and does not report the endpoint-specific number assessed at either time point. Although enrollment is listed as 10, the registry record does not establish that all enrolled participants had evaluable scans at both assessments.

Missing-data procedures are not reported in the registry record. It does not state how missing, unreadable, or incomplete imaging was handled, whether participants without follow-up imaging were excluded, or whether any sensitivity analyses were planned or conducted. Those details matter because incomplete assessment can affect both the denominator and the interpretation of counts over time.

The record also does not describe a statistical analysis plan, interim analyses, or a sample-size justification for the pilot. These items should be treated as not reported in the registry record rather than inferred from the planned imaging schedule or from the separate sample-size planning assumptions.

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 0% reporting threshold.

The registry record lists the Stress Induced Cardiomyopathy Patients group with 5 at risk for serious adverse events and 0 affected. For other adverse events, it lists 5 at risk and 0 affected. No serious adverse-event terms are listed. These are the recorded safety entries; they should not be interpreted as a complete description of event types or follow-up unless that information is documented elsewhere in the registry record.

The deaths field is not populated with a count, so deaths are not reported in the registry record. The record does not explain the safety observation period, the criteria used to classify events, or how the safety denominators relate to the endpoint assessment population. It also does not state whether all enrolled participants were monitored for the same duration.

These entries describe what the registry record reports; they do not establish that no adverse events occurred outside the recorded categories or observation period. They also do not provide evidence about the primary imaging outcome, which is not reported as a participant count.

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

This study is described as a prospective pilot investigation of I-123 mIBG cardiac imaging in stress-induced cardiomyopathy. Its central statistical question is descriptive: how many participants had abnormal regional uptake during the acute phase and how many had abnormal uptake after recovery of cardiac function. The record gives the planned assessment timing and the study's rationale, but not the observed counts.

Because the outcome results and endpoint-specific denominators are not reported in the registry record, readers cannot determine the observed frequency of abnormal uptake, compare the counts across time points, or assess the precision of an estimate. No statistical analyses are listed. A change between assessments, if one were reported, would also need to be interpreted in light of whether participants contributed both observations and how incomplete imaging was handled; those details are not reported.

The study's single-group design does not provide a randomized control comparison. It can be described as a planned investigation of imaging patterns over the acute and recovery phases, but the registry record does not establish that any imaging pattern caused the condition or that the intervention changed the underlying process. The stated hypothesis about sympathetic innervation remains a hypothesis in the absence of reported primary outcome results.

The study description notes that the work may contribute to more specific diagnostic criteria. The record does not report diagnostic accuracy, a comparison with another diagnostic approach, or evidence that diagnostic criteria were developed or validated. The study's objective should therefore be distinguished from an observed diagnostic result.

The safety entries report 0 participants affected among 5 at risk for serious adverse events and 0 among 5 at risk for other adverse events. Deaths are not reported in the registry record. These entries should be read alongside the limitations in safety follow-up detail and do not answer the primary imaging question.

13. Why This Trial Matters Statistically

This trial matters statistically as an example of the difference between a clearly stated research question and a reportable result. The registry record identifies a target population, a specific imaging method, two assessment stages, and a participant-count outcome. Yet without the counts and denominators, readers cannot estimate how often abnormal uptake was observed or how much uncertainty surrounds that estimate.

The design also illustrates why repeated assessments should not be treated as though they came from independent groups. Acute and recovery imaging were planned within a single group. In general, accounting for within-participant relationships is important when studying change over time. The registry record does not report whether paired data were available or how any comparison was analyzed, so the results cannot be interpreted as a quantified within-person change.

A further statistical lesson is that a planning illustration is not the same as the trial's design rationale or its evidential strength. The registry record describes planning assumptions involving two arms, even though the study is recorded as single-group. Those assumptions do not establish observed power or show that the pilot was sized for a particular precision. The pilot's sample-size justification is not reported in the registry record.

Finally, the record demonstrates the importance of reporting endpoint definitions, assessment denominators, missing-data handling, and analysis methods. Those details help readers distinguish an absent result from a result that is simply imprecise, and help determine whether findings can be reproduced or used to design later studies. Here, the registry record supports describing the intended investigation, but not drawing a statistical conclusion about the primary imaging outcome.

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.

This trial has limitations specific to its registry record and design. It is a single-group pilot with allocation listed as NA and masking listed as none. There is no randomized control group, so the planned acute and recovery observations cannot serve as a randomized comparison. The registry record does not describe an analysis method for comparing those observations.

The primary outcome counts are not reported in the registry record. Nor are the numbers of participants with evaluable images at each assessment. Although enrollment is listed as 10, the record does not state how many participants completed acute imaging, follow-up imaging, or both. This prevents assessment of the endpoint denominators and of missing follow-up.

The record does not report the operational criteria for abnormal regional uptake, image-reading procedures, reader masking, or handling of unclear images. It also does not report confidence intervals, statistical tests, or other analyses for the primary outcome. No statistical analysis plan or pilot sample-size justification is reported in the registry record.

The study description identifies Mayo criteria for patient eligibility, but the registry record does not report further details about recruitment, participant characteristics, or how broadly the enrolled group represents patients with stress-induced cardiomyopathy. The sample-size planning assumptions describe a two-arm illustration and are not the design of this single-group study.

These limitations mean that the registry record can describe the study's objectives, planned imaging, timing, and recorded safety entries, but cannot support a numerical interpretation of the primary imaging findings.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pathogenesis of Stress-Induced Cardiomyopathy by I-123 MIBG — NCT01432626.
• Registry record last updated 2016-03-22; status last verified 2016-03.
• Results first posted 2016-03-22.
• 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 record describes a completed, prospective pilot study sponsored by the University of Pittsburgh, with enrollment listed as 10. The study evaluated planar and SPECT I-123 mIBG cardiac imaging in patients with stress-induced cardiomyopathy during the acute phase and after recovery of cardiac function. The acute assessment was planned at 2-5 days, with an expected mean of 3 days, and follow-up at 6 weeks.

The primary outcome was the number of participants with abnormal regional uptake at each assessment. Those counts, endpoint-specific denominators, and statistical analyses are not reported in the registry record. The design is single-group, with no randomized comparator and no masking. Safety entries list 0 serious adverse events among 5 at risk and 0 other adverse events among 5 at risk; deaths are not reported in the registry record.