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 Physiologic Assessment of Coronary Stenosis Following PCI (NCT03084367), a registered phase not stated study. The primary outcome is Number of Participants With Residual Ischemia (iFR <0.90).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03084367 |
| Phase | Phase not stated |
| Condition | Coronary Artery Disease, Coronary Stenosis, Angina, Unstable |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 500 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Volcano Corporation |
| Results posted | Yes |
2. Clinical Question
Population
The primary-outcome population is described as 467 participants, with 535 total vessels or units. The study concerns coronary artery disease and stenosis, including stable and unstable angina. The record’s outcome description focuses on treated target vessels after PCI judged angiographically successful by the operator.
Intervention
The diagnostic assessment is iFR pullback after angiographically successful PCI. The registry describes the study as assessing the relationship between the iFR pullback and the distribution of coronary atheroma or stenoses, with QCA used to assess that distribution.
Comparator
No randomized comparator is described. The record lists an iFR post-PCI arm, and allocation is not stated. Therefore, the listed arm should not be interpreted as a like-for-like control comparison or as evidence of a causal contrast between treatment groups.
Primary question
How many participants had residual ischemia, defined as iFR <0.90, after operator-assessed angiographically successful PCI? The success definition includes residual diameter stenosis <50% in any treated lesion in the target vessel. The primary outcome is specified at the end of the procedure or intervention. The registry record does not report the observed primary-outcome count.
3. Trial Design
DEFINE PCI (NCT03084367) is registered as a pilot study titled “Physiologic Assessment of Coronary Stenosis Following PCI.” Its stated purpose is to assess the relationship between iFR pullback and the distribution of coronary atheroma or stenoses, as assessed by QCA, after angiographically successful PCI. The listed intervention is iFR pullback, classified as a diagnostic test.
The registry lists one arm, “iFR post angiographically successful PCI.” It does not describe a randomized allocation, and allocation is not stated. The record therefore does not support interpreting this as a randomized comparison or treating the listed arm as a control group. The record’s enrollment is 500; the primary-outcome population is described separately as 467 participants and 535 total vessels or units. These are distinct registry descriptions and should not be reconciled by assuming a reason for the difference.
The study status is completed. The recorded start date is 2017-06-20 and the primary completion date is 2019-01-18. These registry entries describe the study’s status and timing, but do not by themselves establish when all follow-up or analyses were completed.
Secondary outcomes include cardiac events, target vessel failure, quality-of-life change from baseline to 12 months follow-up, cardiac mortality, target vessel myocardial infarction, target vessel revascularization, recurrent ischemia, and correlation between iFR and angiographic visual interpretation. The record lists 12 outcome measures, but does not report analysis results for them in the information available. It also does not report a detailed protocol, statistical analysis plan, or sample-size justification.
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 | All Participants With Analyzable iFR Pullback Assessment Post Angiographically Successful PCI |
|---|---|
| STARTED | 500 |
| Analyzable iFR Pullback Assessment Post Angiographically Successful PCI | 467 |
| COMPLETED | 463 |
| NOT COMPLETED | 37 |
Reasons for not completing this period:
| Reason | All Participants With Analyzable iFR Pullback Assessment Post Angiographically Successful PCI |
|---|---|
| Lost to Follow-up | 32 |
| Withdrawal by Subject | 4 |
| Other | 1 |
Analysis population for the primary outcome, as defined in the registry: Total vessels/units (535) in participant population (467)
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 | Diagnostic Test: iFR Pullback |
|---|---|---|
| Participants analysed | 500 | |
| Age, Continuous | years | 66.4 (SD 9.9) |
| Sex: Female, Male: Female | Participants | 121 |
| Sex: Female, Male: Male | Participants | 379 |
| Race and Ethnicity Not Collected | Participants | — |
| BMI (Body Mass Index) | kg/m^2 | 30.8 (SD 8.8) |
| Smoker | Participants | 83 |
| Diabetes Mellitus | Participants | 169 |
| Insulin treated diabetes | Participants | 48 |
| Hyperlipidemia | Participants | 351 |
| Hypertension | Participants | 383 |
| Renal disease | Participants | 39 |
| Prior Percutaneous Coronary Intervention (PCI) | Participants | 227 |
| Prior Myocardial Infarction | Participants | 134 |
| Left ventricular ejection fraction (%) | % of blood ejected with each contraction | 56.3 (SD 9) |
| Stable angina | Participants | 212 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Residual Ischemia (iFR <0.90), measured over end of procedure/intervention.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with residual ischemia at the end of the procedure or intervention. Residual ischemia is defined as an iFR measurement <0.90 after PCI that the operator assessed as angiographically successful. The definition also specifies residual diameter stenosis <50% in any treated lesion in the target vessel. The outcome is therefore a binary event summarized as a count of participants, rather than a continuous measurement or a time-to-event outcome.
As a general statistical point, a prespecified threshold turns a measurement into an event classification that can be counted. This can make the outcome straightforward to describe, but it also means the result depends on the chosen threshold and on how measurements are obtained. The registry record does not report further details about measurement procedures, repeatability, or handling of values near the threshold.
The endpoint addresses residual ischemia after PCI that appears successful by angiography; it is not itself a measure of long-term clinical events. The record lists the outcome population as 467 participants and 535 total vessels or units. It does not report the observed number meeting the residual-ischemia definition, so the endpoint’s result and its precision cannot be evaluated from the registry record. The stated endpoint should also be distinguished from the listed secondary outcomes, which include clinical events and quality-of-life change.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines a clinically focused measurement question: after PCI judged angiographically successful, how many participants had an iFR measurement below the stated threshold for residual ischemia? It identifies the primary endpoint and its timing, but does not report the observed primary-outcome count. Consequently, the endpoint’s frequency, uncertainty, and relationship to other measures cannot be described from the record.
The primary population is described as 467 participants and 535 total vessels or units. Those figures indicate that the record includes both a participant count and a vessel or unit count. They should not be treated as interchangeable denominators. In general, measurements from multiple vessels within a participant may be statistically related. An analysis of vessel-level observations may therefore need to account for clustering; the registry record does not report whether such an analysis was conducted.
The study is described as a pilot assessment of the relationship between iFR pullback and the distribution of atheroma or stenoses assessed by QCA. That aim is distinct from testing whether a treatment improves outcomes. No randomized comparison is described, and the record says allocation is not stated. The data should therefore not be read as a controlled estimate of a treatment effect.
The record lists secondary outcomes, including cardiac events, target vessel failure, mortality, myocardial infarction, revascularization, recurrent ischemia, quality-of-life change, and correlation with angiographic visual interpretation. Although these outcomes indicate the areas of interest, their results are not reported in the registry information available. The record lists 12 outcome measures and 0 analyses; this does not establish what analyses may have been conducted outside the registry record.
The safety listing reports 12 under the serious adverse-event affected count, with 467 at risk, and 0 under the other adverse-event affected count, with 467 at risk. It also lists 0 deaths. The record’s serious-event terms include recurrent ischemia at 1.5%, target vessel myocardial infarction at 1.3%, ischemia-driven target vessel revascularization at 0.0%, and cardiac death at 0.0%. These entries describe what is recorded, not a comparison with another group. The record does not provide enough information to infer the completeness of event capture, attribution, or the relationship of these events to the diagnostic assessment.
Overall, the registry describes the question and the intended endpoint clearly enough to identify what was to be counted. It does not provide the primary count or statistical uncertainty, so no conclusion about the magnitude or precision of residual ischemia can be drawn from the listed endpoint information alone.
9. Statistical Methods Explained
What kind of endpoint is this? The registry classifies the primary outcome as binary and describes it as a number of participants with an event. Each participant is classified according to whether the post-PCI iFR measurement meets the residual-ischemia definition. In general, binary outcomes are commonly presented as event counts and denominators, with an estimate of the event proportion and a confidence interval. A confidence interval conveys the range of values compatible with the observed data under the analysis assumptions; it does not guarantee that the true value lies in that range. The registry record does not report the primary event count, an estimated proportion, or a confidence interval.
What does the threshold do? The endpoint defines residual ischemia as iFR <0.90. Turning a measurement into an event at a threshold can make the outcome easier to interpret as a count, but discards detail about the actual measurement values. General considerations include whether measurement error could affect classification near the cutoff and whether the threshold was specified before examining results. The registry record does not report additional information about measurement variability or the endpoint’s analysis specification.
What is the relevant analysis unit? The record describes 467 participants and 535 total vessels or units for the primary population. A participant-level endpoint counts participants, while vessel-level measurements refer to units within participants. In general, multiple observations from one participant may be correlated rather than independent. Treating correlated observations as independent can make standard errors too small and confidence intervals too narrow. Methods such as participant-level summaries or models that account for clustering can address this issue, depending on the analysis question. The registry record does not say which approach was used.
What does “recalculated” mean in general? Recalculated estimates, when reported, are simple unadjusted calculations from posted summary statistics; they are not necessarily the sponsor’s prespecified analysis. If recalculated results disagree with the sponsor’s analysis, the sponsor’s own analysis takes precedence. No recalculated primary estimate is reported in the registry information available. This distinction matters because summary-statistic calculations may not reproduce adjustments, population rules, or other details used in an original analysis.
How should planning illustrations be read? The record describes sample-size illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is a stated fraction of the observed effect. These are planning illustrations, not observed power and not the trial’s own design justification. For non-time-to-event outcomes, the described convention is participants per arm; for time-to-event outcomes, it is total events using the Schoenfeld method. No illustration values are reported in the registry information available. In general, planning estimates depend on assumptions about the target effect, allocation, significance level, and analysis method. They do not establish that a study was adequately powered for its actual results.
Why can over-dispersion matter? In general, a model for counts may assume that variability follows a particular distribution. Over-dispersion means the data vary more than that model expects. If it is ignored, standard errors may be underestimated and inferential results may appear more precise than warranted. This issue is relevant to count analyses generally, but the registry does not report a count-model analysis or whether over-dispersion was assessed. The primary outcome is described as a participant count for a binary event, and no model details are reported.
What is not available for evaluating the analysis? The registry record does not report the primary event count, confidence interval, statistical test, model specification, covariate adjustment, or handling of missing endpoint data. It also does not report an interim-analysis plan, sample-size justification, or detailed statistical analysis plan. These omissions prevent an assessment of the endpoint’s precision and the exact methods used to produce any result beyond the registry information.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 12 outcome measures, including the primary residual-ischemia endpoint and secondary outcomes covering cardiac events, target vessel failure, quality-of-life change, mortality, myocardial infarction, revascularization, recurrent ischemia, and the relationship between iFR and angiographic visual interpretation. It lists 0 analyses. The registry record does not report how many statistical tests were conducted, which outcomes were formally tested, or whether any adjustment for multiple comparisons was planned or used.
As a general statistical matter, examining multiple outcomes or tests increases the chance of finding an apparently notable result by chance if each is interpreted separately. Prespecifying a primary outcome and clearly distinguishing it from exploratory outcomes can help readers interpret findings. The registry identifies a primary endpoint, but does not provide a detailed hierarchy or multiplicity strategy. No conclusion about whether multiplicity was addressed can be drawn from the listed information.
The registry record does not report the amount or pattern of missing primary-outcome data, exclusions from the analysis, imputation methods, or sensitivity analyses. The primary-outcome population is described as 467 participants and 535 total vessels or units, while the enrollment is 500. These figures alone do not explain the difference or establish why participants or units may be absent from a particular analysis.
The record also does not define a detailed analysis population beyond the described primary-outcome population and the safety group of participants with analyzable iFR pullback assessment after angiographically successful PCI. It does not report whether all enrolled participants were included in each outcome analysis or how incomplete follow-up was handled. These omissions limit assessment of potential bias from missing data or analysis-population choices.
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 |
|---|---|---|---|
| All Participants With Analyzable iFR Pullback Assessment Post Angiographically Successful PCI | 12 | 467 | 2.6% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| All Participants With Analyzable iFR Pullback Assessment Post Angiographically Successful PCI | 0 of 467 |
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 |
|---|---|
| All Participants With Analyzable iFR Pullback Assessment Post Angiographically Successful PCI | 0 of 467 |
Most frequent serious adverse event terms
| Event term | Organ system | All Participants With Analyzable iFR Pullback Assessment Post Angiographically Successful PCI |
|---|---|---|
| Recurrent Ischemia | Cardiac disorders | 7 of 467 |
| Target Vessel Myocardial Infarction | Cardiac disorders | 6 of 467 |
| Ischemia-driven Target Vessel Revascularization | Cardiac disorders | 0 of 467 |
| Cardiac Death | Cardiac disorders | 0 of 467 |
Serious events with the highest arm-level rate: recurrent ischemia (1.5%), target vessel myocardial infarction (1.3%), ischemia-driven target vessel revascularization (0.0%), cardiac death (0.0%).
The adverse-event listing describes the group as all participants with analyzable iFR pullback assessment after angiographically successful PCI. It records 467 at risk and 12 affected for serious adverse events, and 467 at risk and 0 affected for other adverse events. The listing also records 0 deaths. These are counts as entered in the registry; they are not a comparison between randomized groups.
The serious-event terms are listed as recurrent ischemia, 1.5%; target vessel myocardial infarction, 1.3%; ischemia-driven target vessel revascularization, 0.0%; and cardiac death, 0.0%. The percentages are registry entries and should not be added together. The record does not explain whether terms could overlap, how events were attributed, or how the percentages were calculated.
In general, safety counts depend on event definitions, surveillance, follow-up, and the population included. The registry record does not report enough detail to assess those features or to determine whether all events were captured. These entries describe reported safety information; they do not establish a causal relationship between an event and iFR pullback.
12. What the Result Does, and Does Not, Mean
The registry record establishes the study’s stated purpose: to assess the relationship between iFR pullback and the distribution of coronary atheroma or stenoses assessed by QCA after angiographically successful PCI. It also specifies a primary endpoint, a threshold defining residual ischemia, and the timing of assessment. These details clarify what the primary outcome was intended to represent.
However, the registry information does not report the observed primary endpoint count. Without that result, its frequency and statistical precision cannot be evaluated. The record also does not provide an estimate of association between iFR pullback and QCA findings, despite describing that relationship as the pilot study’s purpose. The registry’s listed secondary outcomes likewise do not have results in the information available.
The study is not described as a randomized comparison, and allocation is not stated. Its registry entry therefore does not support a causal comparison between iFR pullback and a control strategy. The listed safety counts are descriptive entries for the group with analyzable assessments, not evidence that the diagnostic test caused or prevented events.
As a general matter, a registry endpoint definition and a completed status are not substitutes for reported results. Interpretation of an observed association or event count would also depend on the analysis population, missing data, measurement procedures, and statistical methods. Those details are not reported in the registry record. The information supports a description of the study question and outcome definitions, but not a conclusion about clinical effectiveness or the magnitude of any relationship.
13. Why This Trial Matters Statistically
This trial is statistically notable for distinguishing an anatomic assessment from a physiologic measurement after PCI. Its stated pilot question concerns the relationship between iFR pullback and the distribution of coronary atheroma or stenoses assessed by QCA. That is an association question, rather than a randomized comparison of treatments.
The primary outcome is also precisely framed as a threshold-based event: residual ischemia is defined by iFR <0.90 after PCI judged angiographically successful, with residual diameter stenosis <50% in any treated lesion in the target vessel. Such definitions help make an endpoint interpretable and reproducible in principle. At the same time, the result depends on the measurement and cutoff, and the registry record does not report further measurement details or the observed event count.
The population description includes both participants and vessels or units. This distinction matters statistically because multiple units may belong to the same participant. Analyses that use unit-level observations may need to account for within-participant dependence; whether that was done is not reported.
The record also illustrates why study status and endpoint definitions are not enough to assess evidential strength. The primary result, uncertainty estimate, analysis methods, missing-data handling, and multiplicity strategy are not reported. The registry describes 12 outcome measures and 0 analyses, but that listing does not establish what statistical work occurred outside the record. The study is informative as a registry description of a pilot measurement question, while the available record does not permit an evaluation of the estimated relationship or its precision.
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 main limitation for interpreting this trial from the registry record is that the primary endpoint is defined but its observed count is not reported. No confidence interval or other measure of uncertainty is listed. The record therefore does not allow evaluation of the endpoint’s frequency or precision.
The study’s stated pilot aim is to assess the relationship between iFR pullback and QCA-assessed distribution of atheroma or stenoses, but an association estimate is not reported. The registry also lists secondary outcomes without their results. Although the record reports 12 outcome measures and 0 analyses, it does not provide a detailed statistical analysis plan or specify which analyses were performed.
The primary population description includes 467 participants and 535 vessels or units. The registry does not explain how these units were selected or analyzed, whether more than one unit per participant contributed measurements, or whether any statistical method accounted for dependence among units. The enrollment is 500, but the record does not explain the distinction between enrollment and the primary-outcome population.
Allocation is not stated, and no randomized comparator is described. The record should therefore not be interpreted as a controlled treatment comparison. The registry does not report missing-data handling, exclusions, measurement-repeatability information, a sample-size justification, or an interim-analysis plan. These limitations concern what is documented in the registry record and do not establish what may be described in other study materials.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Physiologic Assessment of Coronary Stenosis Following PCI — NCT03084367.
- Registry record last updated 2022-05-10; status last verified 2022-02.
- Results first posted 2022-05-10.
- 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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18. Record Summary
DEFINE PCI (NCT03084367), sponsored by Volcano Corporation, is registered as a completed pilot study of physiologic assessment after PCI. The recorded study start date is 2017-06-20, and the primary completion date is 2019-01-18. Enrollment is listed as 500.
The study’s stated aim is to assess the relationship between iFR pullback and the distribution of coronary atheroma or stenoses assessed by QCA after angiographically successful PCI. The primary endpoint is the number of participants with residual ischemia, defined as iFR <0.90, assessed at the end of the procedure or intervention. The population description gives 467 participants and 535 total vessels or units.
The record lists 12 outcome measures and 0 analyses. It does not report the primary outcome count, an association estimate, or statistical uncertainty. Allocation is not stated, and no randomized comparator is described. Safety entries include 12 serious adverse events, 0 other adverse events, and 0 deaths in the listed group with analyzable iFR pullback assessment.