Attain Success Clinical Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Attain Success Clinical Trial (NCT00990964), a registered phase not stated study. The primary outcome is Subjects Successfully Implanted With an Attain Family Left-heart Lead Using an Attain Family Delivery Catheter.

2. Clinical Question

The registry describes a procedural question: whether the specified lead could be placed successfully using the specified delivery catheter family. It also states that the purpose was to assess complication rate. These are distinct aims. Implant success concerns completion of the defined placement procedure; complication reporting concerns adverse events. Neither statement alone establishes how the results compare with another device, procedure, or expected performance.

The available record identifies the condition, device, enrollment, and primary endpoint definition, but it does not report enough information to characterize who was eligible or how participants were selected. Those details matter when judging to whom results might apply. The endpoint population is also not specified. Without a reported primary outcome count or analysis, the clinical question can be described, but the magnitude and precision of the observed implant-success result cannot be assessed from this record.

3. Trial Design

The Attain Success Clinical Trial is listed as completed, with a start of 2009-11 and primary completion of 2011-11. The sponsor is Medtronic Cardiac Rhythm and Heart Failure. The registered enrollment is 2014. The listed intervention is the Attain Success Lead, classified as a device, and the condition is Heart Failure.

The study purpose in the registry record is to assess lead implant success and complication rate using the Medtronic Attain Family of left-heart leads and delivery catheters. The primary outcome is defined as the number of participants successfully implanted with an Attain Family left-heart lead using an Attain Family delivery catheter. The timeframe is implant. The accompanying definition describes final successful placement in coronary vein branches using the Attain Family of delivery catheters.

Allocation is not stated. Randomization, masking, a control group, treatment assignment procedures, and the number of trial arms are not reported in the registry record. A comparator is not reported either. The record lists a device intervention and an Attain Family Lead safety group, but those entries do not establish that participants were assigned to comparable groups. They therefore do not support a randomized treatment-effect interpretation.

The registry lists two outcome measures and two analyses, but additional detail about the second measure and the analyses is not reported in the registry record. A protocol, analysis plan, sample-size justification, interim analysis plan, and participant flow are also not reported in the registry record. The listed enrollment and study dates describe the registry record; they do not, by themselves, clarify how many participants contributed data to each analysis or whether every enrolled participant was followed for the same duration.

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 Subjects Successfully Implanted With an Attain Family Left-heart Lead Using an Attain Family Delivery Catheter, measured over Implant.

The primary endpoint measures the number of participants whose Attain Family left-heart lead was finally placed successfully in coronary vein branches using an Attain Family delivery catheter. Its timeframe is implant. This is a binary outcome at the participant level: a participant either meets the stated success definition or does not. The registry describes the reported quantity as a number of participants, rather than a continuous measurement such as a score or a measurement on a scale.

For a procedural study, an endpoint defined around successful completion can directly describe whether the intended placement was achieved. The registry’s definition makes the procedural criterion explicit: final successful placement in the specified branches using the specified catheter family. General statistical context: a clearly specified endpoint helps readers understand what event is being counted and when it is assessed. It does not, on its own, show how often the event occurred or how precisely it was estimated.

The registry record does not report a numerical primary endpoint result, the number analyzed, or the number meeting the success definition. It also does not report how missing or indeterminate implant outcomes were handled. Consequently, no observed success proportion or confidence interval can be described from the registry record. The endpoint’s clinical interpretation is further limited by the absence of a reported comparator: a count of successful placements, even if available, would describe the recorded experience rather than establish a comparative effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of endpoint is being assessed?

The primary outcome is a count of participants meeting a defined success criterion. The criterion is final successful placement of the Attain Family left-heart lead in coronary vein branches using an Attain Family delivery catheter, assessed at implant. General statistical context: this is a binary endpoint because each participant’s outcome is classified according to whether the defined event occurred. When binary outcomes are reported, readers commonly need both the event count and the number assessed to understand the observed frequency. Neither the primary event count nor its analysis denominator is reported in the registry record.

What does the registry say about the analysis?

The registry identifies two analyses and two outcome measures, but detailed methods for those analyses are not reported in the registry record. The analysis population, handling of missing outcomes, and any adjustments or subgroup analyses are not reported. A protocol and statistical analysis plan are not reported in the registry record either. It is therefore not possible to determine from this record whether the endpoint was analyzed as planned, what assumptions were used, or how departures from a planned analysis would have been handled.

General statistical context: analysis populations define which participants contribute to a result. For example, an analysis may include all assigned participants, all participants who received a device, or only participants with an evaluable endpoint. These choices can affect the meaning of a reported result. Because the registry does not describe the analysis population, the enrollment figure cannot be treated as the primary endpoint denominator.

How should uncertainty be considered?

General statistical context: a point estimate gives a single summary of an observed outcome, while a confidence interval gives a range of values compatible with the data under the chosen method. A confidence interval is informative only when the estimate, denominator, and method are available. The registry does not report a primary endpoint estimate or interval, so the precision of implant success cannot be evaluated from this record.

For binary data, uncertainty depends on the observed event count and the number assessed, as well as on the interval method. Different methods can behave differently, particularly when event counts are small or outcomes are near the limits of the possible range. The registry record does not identify an interval method for the primary endpoint. No method should be inferred from the endpoint description alone.

What do the planning assumptions mean?

The stated sample-size assumptions describe a planning illustration based on an observed effect, not the trial’s own design. The assumptions specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. General statistical context: such a calculation asks how many participants per arm would be needed under selected assumptions to have a chosen probability of detecting an effect of a particular size, if that effect and the model assumptions were correct.

These assumptions do not show that the trial randomized participants, used equal allocation, or planned a two-arm design. Allocation is not stated and a comparator is not reported in the registry record. The planning assumptions must not be read as a description of the trial’s actual design. Nor do planning illustrations establish observed power. They are not a substitute for the observed endpoint result and its uncertainty.

The stated illustration uses the observed effect, but a numerical primary endpoint result is not reported in the registry record. Therefore, no planning quantity or effect magnitude can be independently interpreted from the information in the record. A sample-size illustration also depends on choices such as the target effect and significance level. Different assumptions can lead to different planning results, so an illustration is conditional rather than a guarantee of a study’s ability to answer its question.

Why can over-dispersion matter?

General statistical context: over-dispersion occurs when the variation in data is greater than a statistical model expects. If it is present but ignored, standard errors can be too small and confidence intervals too narrow, making estimates appear more precise than warranted. It is relevant to outcomes modeled as counts or rates when observations vary more than the selected model allows. The primary endpoint in this registry is defined as a participant count with a binary success criterion, and the registry does not report an over-dispersion assessment or model. It would be inappropriate to claim that over-dispersion was present or that a particular adjustment was used.

For the adverse-event entries, interpretation also depends on what is counted: participants with an event, event occurrences, or another unit. The record gives affected counts and percentages in its adverse-event information, but detailed definitions and denominator conventions for the listed terms are not reported. General statistical context: repeated events in one participant and events in different participants are not interchangeable for statistical analysis. The record does not provide enough detail to determine how such issues were handled.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Attain Family Lead and Catheter Attempt")
n      <- c(1917)
events <- c(1802)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Attain Family Lead and Catheter Attempt  1917  1802  94.0  92.8  95.0  92.8  95.0  92.8  95.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and two analyses. The details of the additional outcome measure and the analysis methods are not reported in the registry record. A prespecified hierarchy of outcomes, designation of secondary endpoints, adjustment for multiple comparisons, and rules for interpreting several statistical tests are not reported either. It is therefore not possible to determine whether multiplicity was addressed, or whether any reported analysis was intended to be confirmatory rather than descriptive.

General statistical context: when several outcomes, time points, or subgroup comparisons are tested, the chance of obtaining at least one apparently notable result can increase. Multiplicity methods can control that risk, but the appropriate approach depends on the study’s aims and analysis plan. No specific approach should be assumed in the absence of reported methods. The registry record does not provide a basis for assessing the effect of multiple testing on the results.

Missing-data methods and the number of participants with missing primary endpoint information are not reported in the registry record. The endpoint population is also not specified. Without those details, it is unclear whether the primary analysis included all enrolled participants or a subset, and whether missing outcomes were excluded, imputed, or otherwise addressed. No such method can be inferred from the enrollment figure.

Analysis populations, interim analyses, stopping rules, and a statistical analysis plan are not reported in the registry record. These omissions limit assessment of whether analyses were prespecified and how complete the evidence is. They do not establish that any particular practice was or was not used; they mean those details are unavailable in the registry record.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: device dislocation (1.4%), device stimulation issue (0.4%), implant site infection (0.2%), device capturing issue (0.1%), device pacing issue (0.1%).

The safety information lists the Attain Family Lead group with 2014 at risk, 55 serious adverse events, and 0 other adverse events. The top serious terms are device dislocation at 1.4%, device stimulation issue at 0.4%, implant site infection at 0.2%, device capturing issue at 0.1%, device pacing issue at 0.1%, and ventricular tachycardia at 0.1%. These figures should be read as registry entries, not as a comparative safety estimate.

The registry record does not report the denominator or calculation convention behind the percentages attached to the serious terms. It also does not provide detail on event timing, severity definitions, relatedness assessments, recurrence, or how participants with multiple events were counted. As a result, the percentages should not be treated as participant-level risks unless the registry specifies that interpretation. The count of 55 is reported under serious adverse events, while 0 is reported under other adverse events; the record does not provide further definitions in the registry record.

A comparator and allocation method are not reported in the registry record. The safety entries therefore do not establish whether the listed event counts differ from another device, procedure, or group. They describe reported events in the named group. General statistical context: safety counts are most interpretable when the event definition, time at risk, number of participants assessed, and counting rules are clear. Several of those details are not reported in the registry record.

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

The registry record describes a device study focused on implant success and complications. It defines the primary endpoint in procedural terms and identifies implant as the assessment timeframe. The record also gives enrollment and safety-event entries. These registry entries describe the study’s stated question and selected reported information, but the registry does not report the numerical result for the primary endpoint.

Accordingly, the record cannot establish how many participants met the implant-success definition, how precisely success was estimated, or whether the outcome satisfied a prespecified performance criterion. A completed status does not answer these questions. Nor do the adverse-event entries, on their own, establish a comparative safety profile. The registry record does not report a comparator or allocation method, and no like-for-like control comparison should be inferred.

The safety terms and counts are relevant as reported observations, but the record does not explain the percentage denominators or provide enough detail to interpret event timing, recurrence, or relatedness. The entries should not be converted into additional rates or used to imply a causal effect. They are a description of what the registry lists for the Attain Family Lead group.

General statistical context: estimates are most useful when readers can see the outcome definition, analysis population, event count, denominator, uncertainty, and analysis method. Here, several of those elements for the primary endpoint are not reported in the registry record. This limits the strength of any statistical conclusion that can be drawn, but it does not change the stated purpose or endpoint definition.

The study record may help identify what the investigators intended to assess: placement success and complications with the Attain Family leads and delivery catheters. It does not, by itself, provide a complete account of the evidence needed to judge the frequency of successful implantation, precision, or comparative performance. Those unanswered questions should remain distinct from the outcomes the record actually lists.

14. Why This Trial Matters Statistically

This trial is statistically notable for the contrast between a clearly described procedural endpoint and the absence of its numerical result in the registry record. The definition specifies what counts as success and when it is assessed. That clarity is useful: readers can identify the intended event rather than having to infer it from a broad label. Yet an endpoint definition is not an outcome estimate. Without a reported count and denominator, the observed frequency and precision cannot be evaluated.

The record also illustrates why study design information matters when interpreting device outcomes. The registry lists an intervention and a safety group, but allocation is not stated and a comparator is not reported. This prevents a comparative interpretation. Descriptive event information can characterize what was recorded in a group, but it does not establish how that experience differs from an alternative.

The reported adverse-event terms and figures also show the importance of clear denominators and counting rules. A percentage is only interpretable as a risk or rate when its basis is clear. The registry does not report the denominator convention for the listed term percentages. Statistical interpretation therefore requires restraint rather than treating every percentage as an individual participant’s probability of an event.

Finally, the planning assumptions are distinct from the trial’s actual design. A hypothetical calculation using equal allocation between two arms does not establish that the study used that design, particularly when allocation is not stated. General statistical context: separating planning illustrations from observed evidence helps prevent a calculation about a possible future study from being mistaken for a result of the completed study.

15. 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 interpreting implant success is that a numerical primary endpoint result is not reported in the registry record. The number meeting the success definition, the number analyzed, and an uncertainty estimate are also not reported. Enrollment of 2014 cannot be assumed to be the endpoint denominator or evidence that every participant had an evaluable outcome.

The registry record does not report eligibility criteria, participant characteristics, the endpoint analysis population, missing-outcome handling, or participant flow. These omissions limit assessment of the representativeness and completeness of the primary endpoint data. A protocol, statistical analysis plan, sample-size justification, interim analysis plan, and stopping rules are not reported in the registry record, so prespecification and analysis decisions cannot be assessed.

Allocation is not stated, and a comparator is not reported. The findings therefore cannot be interpreted as a randomized or controlled comparison. The record lists two outcome measures and two analyses, but further outcome and analysis details are not reported. Multiplicity procedures and the handling of multiple outcomes or tests are not reported in the registry record.

The safety information has its own interpretive limits. The record lists 55 serious adverse events and 0 other adverse events for the group, with 2014 at risk, and gives percentages for top serious terms. Definitions for the term-percentage denominators, event timing, recurrence, relatedness, and participant-level counting are not reported in the registry record. These gaps constrain interpretation of the safety entries and prevent a reliable comparison with an unreported control group.

The registry record is marked completed, but completion status does not resolve these data and methods limitations. It indicates the recorded study status, not the completeness or precision of the reported endpoint evidence.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Attain Success Clinical Trial — NCT00990964.
• Registry record last updated 2012-09-12; status last verified 2012-08.
• Results first posted 2012-09-12.
• 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.

19. Record Summary

The Attain Success Clinical Trial is listed as completed, with a start of 2009-11, primary completion of 2011-11, and registered enrollment of 2014. The sponsor is Medtronic Cardiac Rhythm and Heart Failure. Heart Failure is the listed condition, and the Attain Success Lead is the listed device intervention.

The stated purpose is to assess implant success and complication rate using the Medtronic Attain Family of left-heart leads and delivery catheters. The primary endpoint counts participants with final successful lead placement in coronary vein branches using an Attain Family delivery catheter, at implant. Its numerical result is not reported in the registry record.

The adverse-event information lists 55 serious adverse events and 0 other adverse events for the Attain Family Lead group, with 2014 at risk, alongside percentages for top serious terms. Allocation, comparator, detailed analysis methods, endpoint denominator, and missing-data handling are not reported in the registry record. The record therefore describes the study question and selected event entries, but does not provide a numerical primary endpoint estimate or a basis for comparative conclusions.