Utilization of Confocal Microscopy During Cardiac Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Utilization of Confocal Microscopy During Cardiac Surgery (NCT03189134), a na phase 1 study. The primary outcome is Number of Participants Who Experienced Adverse Events Possibly Related to Study Intervention.

2. Clinical Question

The clinical question is about using a confocal microscope during cardiac surgery and collecting safety information while doing so. The study description proposes that the device may help distinguish cardiac tissues, with the stated motivation of avoiding injury to conduction tissue. That rationale is not itself an outcome result. The endpoint named as primary measures adverse events possibly related to the intervention; it does not directly establish whether the images identify tissue types accurately or whether use of the device changes surgical outcomes. The registry record does not report a controlled comparison or an analysis demonstrating diagnostic performance. Accordingly, the question addressed by the posted information is narrow: what adverse-event counts were recorded among participants in this single group, and what can those counts establish about the study intervention in this setting?

3. Trial Design

NCT03189134, titled “Utilization of Confocal Microscopy During Cardiac Surgery,” is recorded as a completed phase 1 study with enrollment of 6. The start date is 2018-04-02 and the primary completion date is 2019-03-04. The registry lists a single-group model, allocation as NA, and masking as NONE. These design features mean there is no randomized or masked comparison described in the record.

The intervention listing includes FLUORESCITE, categorized as a drug, and the Cellvizio 100 Series System with Confocal Miniprobes, categorized as a device. The imaging-arm description says that up to 5mL of 1:1000 dilute FLUORESCITE was applied to cardiac tissue before imaging. The record does not describe a separate control arm or an alternative imaging strategy. As a result, the study is descriptive with respect to the recorded experience of participants in the imaging arm rather than a comparative trial capable of estimating a between-group treatment effect.

The primary outcome is the number of participants who experienced adverse events possibly related to the study intervention. Its timeframe is surgery through discharge, approximately 5 days. The description says all adverse events would be collected and relatedness to the study intervention determined. Two secondary outcomes are named: the number of participants for whom confocal microscopy imaging during cardiac surgery was feasible, and percentage agreement in classification of confocal microscopy images. Numerical findings for those outcomes are not reported in the registry record.

The registry lists 3 outcome measures and 0 analyses. Details about eligibility, recruitment procedures, the statistical analysis plan, and any sample-size justification are not reported in the registry record. The recorded enrollment should therefore be understood as the number enrolled, not as evidence that the study was designed to estimate a particular effect with a specified precision.

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

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 Experienced Adverse Events Possibly Related to Study Intervention, measured over Surgery through discharge (approximately 5 days).

The primary endpoint counts participants who experienced adverse events possibly related to the study intervention. Its stated observation period runs from surgery through discharge, approximately 5 days. The registry description says that all adverse events would be collected and that relatedness to the intervention would be determined. The endpoint is expressed as a participant count, so it concerns how many people had an event rather than the total number of event episodes.

Safety endpoints are used to describe events observed during or after exposure to an intervention and to document investigators’ assessments of whether events may be related to that intervention. In general, collecting all adverse events can capture a broad range of experiences, while an endpoint focused on possibly related events depends additionally on how relatedness is assessed. The registry record does not report the detailed criteria or process used for that assessment.

The adverse-event figures recorded by category do not, by themselves, supply a clearly identified count for the primary endpoint of events possibly related to the intervention. The record lists serious adverse events, other adverse events, and deaths, but does not give the relatedness-specific result for the primary endpoint. It is therefore important not to treat the count of other adverse events as equivalent to the count of possibly related events. Nor does the primary endpoint measure feasibility, image-classification agreement, avoidance of tissue injury, or clinical benefit. Those are distinct questions, and the registry record does not report numerical results for the named secondary outcomes.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study is recorded as a single-group investigation, not a randomized comparison. Its allocation is listed as NA and masking as NONE. The distinction matters because a single-group count describes what happened among participants who received the study intervention, while a controlled comparison estimates how outcomes differ between groups. In general, outcomes after surgery may reflect the procedure, the underlying condition, other care, or the study intervention. Without a concurrent comparator, the observed counts cannot separate those possible influences.

What does a participant count represent?

The primary endpoint is a count of participants who experienced an adverse event possibly related to the study intervention. A participant count counts each affected person rather than counting every event episode. The registry’s adverse-event summary separately reports numbers of participants at risk and affected for serious and other adverse events, along with deaths. Those categories describe safety experience, but they do not automatically equal the primary endpoint because the primary endpoint depends on a relatedness judgment. That specific result is not reported in the registry record.

In general, counts are most interpretable when the outcome definition, observation period, and denominator are clear. The registry names the primary endpoint’s observation period as surgery through discharge, approximately 5 days, and enrollment was 6. The record does not clarify whether all participants had complete observation for that period, whether an event could be counted in more than one category, or how event-relatedness decisions were made. Those details affect how precisely a count can be understood.

Why does the absence of a comparator matter?

A comparison between groups can help distinguish an intervention-associated difference from background events, although it cannot by itself resolve every causal question. Here, the registry describes one imaging arm and no control arm. Thus, there is no between-group contrast to estimate. The safety counts can be reported descriptively, but they cannot establish what would have occurred in similar participants without the study intervention. General statistical concepts such as risk differences or relative risks require defined comparison groups; no such trial comparison is reported in the registry record.

What can uncertainty tell readers?

In general, statistical uncertainty reflects both the amount of information in the data and the assumptions used in an analysis. A confidence interval, when reported, gives a range of values compatible with the data and model; it is not a guarantee that the true value lies in that range. No confidence interval or inferential analysis is reported in the registry record. With only a small enrolled group and no comparator, the descriptive counts provide limited information about the frequency of uncommon events or about differences from other care. A zero observed count is not proof of zero underlying risk.

Over-dispersion is a general concern when event counts vary more than a statistical model assumes. It can make conventional uncertainty estimates too narrow if the model fails to represent that extra variability. The registry record does not report a count model, dispersion assessment, or analysis of repeated event counts. Because the primary endpoint is a participant count, and no inferential model is reported, there is no basis for judging whether over-dispersion was assessed or relevant to a particular estimate.

How should planning illustrations be understood?

The stated planning framework is an illustration based on an observed effect, not the trial’s own design or a reported sample-size justification. It assumes a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is described as a stated fraction of the observed effect. Those assumptions do not match the recorded single-group design. Any resulting sample-size figures are planning illustrations, not observed power and not evidence that the study had a particular probability of detecting an effect. The registry record does not report the study’s own sample-size justification, a planned effect size, or a formal power calculation.

In general, power is a design property calculated under specified assumptions about an effect, variability, analysis, and sample size. It is not a measure of how persuasive a result is after data are observed. Sample-size calculations can help plan future studies, but they do not repair the absence of a comparator or fill in unreported outcomes for this study. The available record does not provide enough information to assess whether the enrolled group was intended to estimate safety, feasibility, or image-classification performance with a particular precision.

What is not available for analysis?

The registry lists 0 analyses. It does not report the statistical analysis methods for the primary endpoint, the analysis population, missing-data procedures, or inferential results. The two secondary outcomes are named, but their numerical findings and analysis methods are not reported in the registry record. Without those details, readers cannot assess whether any stated analysis followed a prespecified plan, how exclusions were handled, or how uncertainty was quantified. A careful reading therefore separates recorded counts from unreported estimates and avoids treating the study rationale as a statistical result.

10. Multiplicity, Missing Data and Analysis Populations

The registry names a primary outcome and two secondary outcomes, and lists 3 outcome measures. The primary outcome is the number of participants with adverse events possibly related to the study intervention. The secondary outcomes concern imaging feasibility and agreement in image classification. Numerical results for the secondary outcomes are not reported in the registry record, and the record lists 0 analyses.

Multiplicity arises when several outcomes or statistical tests are considered. In general, examining more outcomes can increase the chance that at least one result appears noteworthy by chance, so analysis plans may specify how multiple tests will be handled. The registry record does not report a multiplicity procedure, a hierarchy among outcomes beyond the primary and secondary labels, or any hypothesis tests. It is not possible to determine whether multiplicity adjustment was planned or used.

The registry record does not report an analysis population, participant-level data, or a missing-data method. It does not say whether every enrolled participant contributed complete information through discharge, whether anyone was excluded from an outcome analysis, or how incomplete observations were treated. These details matter because an outcome count depends on who was observed and what information was available. The enrollment figure alone does not establish that all participants were included in every outcome assessment.

Relatedness assessment is also important for interpreting the primary endpoint. The description says relatedness would be determined, but the criteria, adjudication process, and relatedness-specific result are not reported in the registry record. In the absence of those details, the adverse-event categories cannot be assumed to provide the primary endpoint result. These reporting gaps limit assessment of both the statistical analysis and the completeness of outcome reporting.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry’s imaging-arm summary records 0 participants with serious adverse events among 6 at risk, 6 participants with other adverse events among 6 at risk, and 0 deaths among 6 at risk. These are counts for the recorded group, not comparisons with another group. The record does not list serious adverse-event terms.

The serious-event count and the other-adverse-event count are distinct categories in the registry summary. The count of 6 with other adverse events should not be read as 6 events, because the summary is expressed as participants affected. It also should not be interpreted as 6 events judged related to the study intervention. The primary outcome is limited to adverse events possibly related to the intervention, but a relatedness-specific count is not reported in the registry record.

In general, adverse-event counts describe what was recorded during a defined observation period; they do not establish causation on their own. The primary endpoint’s stated timeframe is surgery through discharge, approximately 5 days. The registry does not report event descriptions, onset timing, severity details for the other events, or the relatedness assessment results. The zero counts are observations in this study group, not proof that serious events or deaths cannot occur.

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

The posted results establish that the registry records 6 participants in the imaging arm and reports 0 participants with serious adverse events, 6 with other adverse events, and 0 deaths. Those figures provide a descriptive account of the categories recorded for this group. They do not show how these counts compare with usual care, another imaging approach, or no study intervention, because no control arm is described.

The result does not establish that the intervention caused the other adverse events or that it prevented serious adverse events. Attribution requires information about the events and the process used to assess relatedness. Although the registry says relatedness to the study intervention would be determined, that specific result is not reported in the registry record. The reported counts therefore should not be substituted for the primary endpoint’s relatedness-specific count.

The study description proposes using confocal microscopy to distinguish tissue types during surgery. The registry names feasibility and image-classification agreement as secondary outcomes, but their numerical results are not reported. The posted information consequently does not quantify whether imaging was feasible or how often image classifications agreed. It also does not report a clinical outcome demonstrating that tissue injury was avoided. The rationale and proposed use are not findings.

In general, a small descriptive study can document experience and identify questions for further evaluation, but a single group cannot provide a controlled estimate of an intervention effect. No inferential analyses or confidence intervals are reported in the registry record. This means readers cannot assess precision using an interval estimate, and the absence of an observed serious event should not be interpreted as evidence of no underlying risk. The study also does not establish diagnostic accuracy or comparative safety.

The most defensible interpretation is therefore limited: the registry records adverse-event categories among participants who underwent the described imaging procedure, while leaving relatedness, feasibility, agreement, and comparative outcomes unresolved. The record does not support a conclusion that the intervention improves or worsens clinical outcomes.

13. Why This Trial Matters Statistically

This study is statistically important because it illustrates the difference between recording an outcome and establishing an intervention effect. The registry lists safety counts for participants in a single imaging group, but there is no like-for-like control comparison. Those counts can describe the observed experience, yet they cannot show what would have happened to comparable participants without the intervention or under another strategy.

It also highlights the importance of matching outcome results to outcome definitions. The primary endpoint concerns participants with adverse events possibly related to the study intervention. The adverse-event summary separates serious events, other events, and deaths, but the registry does not report a relatedness-specific result. Treating one category as if it answered the primary endpoint would conflate distinct measures.

The named secondary outcomes raise separate statistical questions. Feasibility and agreement in image classification are not interchangeable with safety, and neither is a direct measure of patient benefit. Their numerical results are not reported in the registry record. Without those results and their analysis methods, readers cannot assess the technical performance that motivates the study.

Finally, the record offers an example of why uncertainty and reporting completeness matter. A zero observed count in a small group does not demonstrate that an event is impossible, and an event count without a comparator does not establish causation. The registry’s planning framework is explicitly an illustration rather than the trial’s own design. Clear distinction between descriptive observations, planned analyses, and controlled estimates is essential when interpreting early-stage clinical research.

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 central limitation is the single-group design. There is no comparator, so observed adverse-event counts cannot be contrasted with outcomes under another strategy. The registry lists allocation as NA and masking as NONE; it does not describe a randomized or masked comparison. This limits causal interpretation and comparative safety assessment.

Enrollment was 6, which restricts the amount of descriptive information available about events and leaves substantial uncertainty about events not observed. The registry record does not report confidence intervals or other inferential analyses. It also does not state whether all enrolled participants completed observation through discharge or how incomplete outcome information, if any, was handled.

The primary outcome is relatedness-specific, but the registry does not report the number of participants whose events were judged possibly related to the intervention or the criteria used for that assessment. The adverse-event summary reports serious events, other events, and deaths, but these categories do not resolve that reporting gap. Event descriptions and timing are also not reported in the registry record.

Although feasibility and image-classification agreement are named as secondary outcomes, numerical results and methods for assessing them are not reported. The registry therefore does not permit evaluation of the proposed tissue-discrimination performance. The study’s rationale about avoiding injury to conduction tissue is not accompanied by a reported outcome establishing whether such injury was avoided.

Further limitations include the absence of reported eligibility details, analysis populations, missing-data procedures, multiplicity methods, and a study-specific sample-size justification. The planning assumptions described for an illustration involve two arms, whereas the recorded trial is single-group; they should not be mistaken for the study’s actual design or power calculation. These limitations constrain what can be concluded from the posted record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Utilization of Confocal Microscopy During Cardiac Surgery — NCT03189134.
• Registry record last updated 2020-07-07; status last verified 2020-07.
• Results first posted 2020-07-07.
• 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

NCT03189134 is a completed phase 1, single-group study titled “Utilization of Confocal Microscopy During Cardiac Surgery.” The registry records enrollment of 6 and lists atrial septal defect as the condition. The imaging arm used the Cellvizio 100 Series System with Confocal Miniprobes after application of up to 5mL of 1:1000 dilute FLUORESCITE.

The primary outcome is the number of participants experiencing adverse events possibly related to the study intervention from surgery through discharge, approximately 5 days. The adverse-event summary records 0 participants with serious adverse events, 6 with other adverse events, and 0 deaths. A relatedness-specific primary result is not reported in the registry record. Feasibility and image-classification agreement are named as secondary outcomes, but their numerical results are not reported. No analyses are listed, and there is no control group for comparison.