Longitudinal Surveillance Registry (LSR) of ACUITY Spiral: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Longitudinal Surveillance Registry (LSR) of ACUITY Spiral (NCT00955708), a registered phase not stated study. The primary outcome is Chronic Left Ventricular Lead-related Complication Free Rate.

2. Clinical Question

In practical terms, the study asks how the implanted lead performed over long-term observation with respect to lead-related complications. The endpoint is framed as the proportion remaining free from an event, rather than as a comparison between randomized groups. The registry identifies the population and device but does not report detailed eligibility criteria, the endpoint’s event definition, or the analysis population. Those omissions limit how precisely the question can be translated into a specific estimand—the exact quantity the analysis is intended to estimate. In particular, the record does not establish which complications qualify, how events are adjudicated, or how withdrawal and death enter the calculation. The surveillance question can be described, but its operational details and numerical answer cannot be reconstructed from the registry record.

3. Trial Design

The study is titled Longitudinal Surveillance Registry (LSR) of ACUITY Spiral, with an official title identifying it as a condition-of-approval study of the ACUITY Spiral Lead. Boston Scientific Corporation is the sponsor. The registry lists heart failure as the condition and the ACUITY Spiral Left Ventricular Lead as the device intervention. The stated aim is to evaluate and report on the lead’s long-term performance.

Enrollment is 1308. The record describes an “Implants” group consisting of patients successfully implanted with the lead. It does not describe randomization or a control group; allocation is not stated, and the registry cautions that the arms are not a like-for-like control comparison. Accordingly, the design is best read as surveillance of an implanted cohort, not as a randomized test of one treatment against another.

The study began on 2009-08-04, had a primary completion date of 2018-02-28, and is listed as terminated. The endpoint timeframe runs from enrollment to study completion, with completion described in terms of the date of five-year follow-up, withdrawal or death. The record does not explain how those stopping points were handled in the endpoint analysis or whether every participant had the same observation period.

The registry lists one primary outcome measure and two analyses, but the analytic details and numeric primary-endpoint findings are not reported in the registry record. The record also does not state the enrollment rationale, a formal sample-size justification, the planned analysis model, or whether interim analyses were conducted. These gaps make it possible to identify the broad surveillance design and intended outcome, but not to verify the analysis plan or reproduce the reported primary result.

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.

Population: Baseline data includes data on the patients that received an implant or underwent an attempted implant. This does not include intent patients who were consented but did not participate in the trial and did not undergo anesthesia.

6. Primary Endpoint

The registry lists the primary outcome as Chronic Left Ventricular Lead-related Complication Free Rate, measured over Date of enrollment to study completion (Date of 5 year follow-up, withdrawal or death)..

The primary endpoint is titled “Chronic Left Ventricular Lead-related Complication Free Rate.” Its unit is percent free from event, and its stated timeframe begins at enrollment and continues to study completion, defined as the date of five-year follow-up, withdrawal or death. The endpoint is intended to describe whether lead-related complications occur during longitudinal observation, rather than to estimate a difference between randomized groups.

A complication-free measure can be useful in device surveillance because it focuses on remaining without a specified event over follow-up. A confidence interval communicates the uncertainty around an estimated rate: in general, it gives a range of values compatible with the data under the analysis assumptions. The registry identifies a 95% confidence interval as the dispersion measure for this outcome, but the estimate and interval are not reported in the registry record.

The endpoint title does not specify which events count as chronic lead-related complications, how events are confirmed, or how repeated events are treated. The registry record also does not explain how withdrawal or death affects the calculation, despite naming them as follow-up endpoints. These details matter because the event definition and handling of incomplete observation determine what the resulting rate represents. Without them, the outcome’s broad purpose is clear, but its exact operational meaning and numerical value remain uncertain.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on the quantity being estimated, the way observations are collected, and the assumptions used to analyze them. For this registry, the stated target is a chronic left ventricular lead-related complication-free rate over follow-up. The registry names a 95% confidence interval as the measure of dispersion, but does not report the primary estimate, the interval limits, or the analysis method. General explanations of relevant statistical ideas can clarify what such an endpoint is intended to convey; they cannot fill in those absent results.

What does a complication-free rate describe?

In general, a complication-free rate describes the share of an observed population that has not experienced a defined event by a specified point or over a specified period. For longitudinal data, participants may have different amounts of follow-up. An analysis may account for the timing of events and for incomplete observation, but the appropriate method depends on the protocol and analysis plan. The registry timeframe names enrollment, study completion, five-year follow-up, withdrawal and death. It does not report the event definition or explain the analytic treatment of those follow-up endpoints. It is therefore not possible to determine how the posted endpoint was calculated.

What does a confidence interval contribute?

In general, a confidence interval expresses statistical uncertainty around an estimate under the assumptions of the method used. A narrower interval indicates greater precision under those assumptions; a wider interval indicates less precision. It does not capture every source of uncertainty. For example, uncertainty caused by an incomplete event definition, incomplete follow-up, measurement error, or bias in who entered the registry may not be represented by the interval. Since the registry record does not give the primary estimate or interval limits, neither the estimated rate nor its precision can be assessed in this case.

Why does the comparison structure matter?

A randomized comparison is designed to make groups comparable, on average, with respect to factors that could affect an outcome. This record does not describe a randomized comparison, and it explicitly cautions that the arms are not a like-for-like control comparison. The described “Implants” group is a surveillance cohort of patients successfully implanted with the lead. The findings can be read as observations in that group, but they do not by themselves estimate a causal difference against an alternative. General statistical adjustment can sometimes address measured differences between groups, but the registry record does not report an adjustment plan or model.

How should counts and percentages be read?

Counts identify how many events or affected participants are recorded under a given category, while a percentage expresses a proportion relative to some denominator. For the adverse-event listing, the registry reports 117 affected by serious adverse events and 131 affected by other adverse events, with 1303 at risk in each listing. It also reports 269 deaths. The record does not explain whether categories overlap, whether the same person can contribute more than one event, or the observation period used for these counts. The listed serious-event percentages have no stated denominator or calculation basis in the record. They should be understood as descriptive entries, not reinterpreted into new rates.

What does over-dispersion mean in general?

For count outcomes, a basic statistical model may assume that variability is tied to the mean. Over-dispersion occurs when the observed variation is greater than that model expects. If not accounted for, standard errors may be too small and confidence intervals or tests may suggest more precision than the data justify. This is a general consideration for analyses of event counts; the registry record does not state that over-dispersion was assessed or that a count model was used in this study. No specific claim about the study’s analysis follows from this general explanation.

How should planning illustrations be interpreted?

Planning sample-size illustrations are conditional calculations, not observed outcomes. The stated illustrations use 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. For time-to-event tables, the illustration is expressed as a total number of events, while other tables express participants per arm. These are planning conventions and do not establish that the trial used those assumptions. The record explicitly identifies the illustrations as separate from the trial’s own design. They are not observed power and cannot establish whether the study was adequately designed or whether its result is conclusive.

The registry lists two analyses but does not describe their models, covariates, handling of censoring, or relationship to the primary endpoint. Nor does it report whether assumptions were checked or how uncertainty was calculated. These omissions prevent independent reproduction of the analysis. A defensible reading separates the endpoint’s stated purpose from the method details that are not reported, and treats all general statistical explanations as context rather than descriptions of what the study actually did.

10. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when several outcomes, comparisons, subgroups or repeated analyses are examined. In general, conducting many statistical tests can increase the chance of finding an apparently notable result by chance. A prespecified testing hierarchy, adjustment procedure or clear distinction between confirmatory and exploratory analyses can help readers understand how multiple analyses were handled. The registry lists one primary outcome measure and two analyses, but does not describe the analyses or report a multiplicity strategy. It is therefore not possible to determine whether adjustment was needed or applied.

The record does not report whether interim analyses were planned or conducted, or whether any stopping rules were used. The study is listed as terminated, but the reason and any statistical implications are not reported in the registry record. Termination alone does not establish that the study stopped early for a particular reason or that the analysis was affected in a particular way.

Missing data and incomplete follow-up are especially relevant to a longitudinal complication-free endpoint. The timeframe refers to follow-up until study completion, the date of five-year follow-up, withdrawal or death. The registry does not describe how participants with incomplete follow-up were handled, whether withdrawals were treated as censoring, or how deaths entered the endpoint analysis. It also does not report missing-data procedures or sensitivity analyses. In general, conclusions can depend on assumptions about outcomes after observation ends; those assumptions should be stated and examined.

The analysis population is not detailed beyond the description of the “Implants” group as patients successfully implanted with the lead. The record does not explain which participants were included in each analysis or how exclusions were handled. The enrollment figure is 1308, while the at-risk figure in the adverse-event group is 1303; the reason for the difference is not reported in the registry record. Without participant flow and analysis-population definitions, the connection between enrollment, follow-up and analyzed outcomes remains unclear.

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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: lead dislodgment, left ventricular (2.2%), threshold related, left ventricular (1.5%), extracardiac stimulation, left ventricular (0.8%), infection, procedure related (0.8%), erosion/migration (0.7%).

The adverse-event listing identifies an “Implants” group with 1303 at risk. It reports 117 affected by serious adverse events, 131 affected by other adverse events, and 269 deaths. These figures should be read as registry-reported counts. The record does not specify whether the same participants appear in more than one category, whether the entries count people or event occurrences in all cases, or the observation period associated with the counts.

The listed serious-event terms and percentages are Lead Dislodgment, Left Ventricular (2.2%), Threshold Related, Left Ventricular (1.5%), Extracardiac Stimulation, Left Ventricular (0.8%), Infection, Procedure related (0.8%), Erosion/Migration (0.7%), and Lead Dislodgment, Atrial Lead (0.5%). The denominator and calculation basis for these percentages are not reported in the registry record. They should not be converted into incidence rates or compared as if their denominators and follow-up were known.

These safety entries do not establish that the device caused an event, and the deaths cannot be attributed to the lead from the counts alone. There is no like-for-like control comparison described. The adverse-event information is therefore descriptive and should be kept separate from the primary complication-free endpoint, whose numeric result is not reported.

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

The registry record identifies a long-term surveillance question: the performance of the ACUITY Spiral Left Ventricular Lead with respect to chronic lead-related complications. It also provides descriptive adverse-event counts and a list of serious-event terms with percentages. Those details establish what kinds of outcomes the record addresses, but they do not supply the primary endpoint’s numerical answer. The complication-free rate and its 95% confidence interval are not reported in the registry record.

The record does not describe a randomized, like-for-like control comparison. As a result, the information cannot establish a comparative effect against another device or a no-device control. In general, observations from an implanted cohort can characterize outcomes recorded during follow-up, but cannot alone separate device-related effects from differences in patient characteristics, clinical care, or other influences. The registry does not report methods that would resolve those limitations.

The adverse-event counts also require restraint. The serious and other adverse-event categories may not be mutually exclusive, and the relation between those categories and the death count is not reported. The listed percentages have no stated denominator or calculation basis. Thus they should not be treated as comparable risks or as proof of causation. The record does not provide enough detail to determine how long participants were observed for those counts or how loss to follow-up was handled.

The listed enrollment is 1308, whereas the adverse-event group lists 1303 at risk. No explanation is reported for the difference. The study’s terminated status is recorded, but a reason for termination is not given. These registry entries do not establish why participation or follow-up ended or whether the termination affected the findings.

Accordingly, the record supports a limited conclusion about the kind of surveillance undertaken and the descriptive counts it reports. It does not permit a quantitative conclusion about the primary complication-free rate, a causal claim about the device, or a reliable comparison of event risks. A fuller interpretation would require the endpoint estimate, confidence interval, event definitions, follow-up details, analysis population and methods, none of which are reported in the registry record.

13. Why This Trial Matters Statistically

This registry illustrates an important statistical distinction between surveillance and comparative evaluation. Its stated purpose is to evaluate and report on long-term performance of a device. The described “Implants” group and the absence of a like-for-like control comparison mean the evidence is principally descriptive. That design can document events observed during follow-up, but it does not provide the same basis for attributing differences in outcomes to a device as a well-defined comparative design.

The endpoint also highlights why a result needs more than a name. A complication-free rate depends on what qualifies as a complication, how time is handled, and what happens analytically when follow-up ends. The registry names follow-up through study completion, five-year follow-up, withdrawal or death, but does not report the event definition or handling of these endpoints. Without those details, readers cannot fully identify the quantity being estimated.

Precision is another key issue. The registry specifies a 95% confidence interval, but does not report its limits or the primary estimate. A confidence interval is useful only when the estimate and its uncertainty can be evaluated alongside the analysis assumptions. The missing primary result prevents that assessment, regardless of the adverse-event counts elsewhere in the record.

Finally, the difference between enrollment and the at-risk figure, the lack of analysis-population details, and the unspecified basis of the event percentages show why participant flow and denominators matter. The record gives useful context for the study’s purpose and some safety categories, while also demonstrating that interpretable surveillance evidence depends on transparent outcome definitions, follow-up accounting and analytic reporting.

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.

Several limitations are specific to the information recorded for this study. Most importantly, the numeric primary endpoint and 95% confidence interval are not reported in the registry record. The central question—how often participants remained free from chronic left ventricular lead-related complications—therefore has no interpretable numerical answer in the available record.

The endpoint title does not define the qualifying complications, and the record does not explain event adjudication, repeated events, or the treatment of withdrawal and death in the calculation. Although the timeframe refers to the date of five-year follow-up, withdrawal or death, the handling of unequal follow-up is not described. These omissions limit clarity about the target estimand and how it was measured.

The registry describes an implanted cohort and cautions that the arms are not a like-for-like control comparison. Allocation is not stated, and no comparative analysis details are reported. This restricts causal interpretation. The record does not report an analysis plan, model, covariate adjustment, interim analyses, multiplicity handling, missing-data procedures, or sensitivity analyses. The number of analyses is listed, but their purpose and methods are not described.

Enrollment is 1308, while 1303 are listed at risk in the adverse-event group; the reason for this difference is not reported. The adverse-event counts do not clarify category overlap or the observation time, and the denominator for the listed serious-event percentages is not reported. The record lists 269 deaths without explaining their relationship to the device or other event categories. The study is marked terminated, but the reason is not reported in the registry record. Together, these gaps limit reproducibility and the scope of conclusions that can be drawn from the posted information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Longitudinal Surveillance Registry (LSR) of ACUITY Spiral — NCT00955708.
• Registry record last updated 2019-05-02; status last verified 2018-07.
• Results first posted 2019-05-02.
• 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 the Longitudinal Surveillance Registry of ACUITY Spiral, a condition-of-approval study of the ACUITY Spiral Lead sponsored by Boston Scientific Corporation. Heart failure is the listed condition, and the intervention is the ACUITY Spiral Left Ventricular Lead. The stated purpose is to evaluate and report on long-term lead performance. Enrollment is 1308; the study began on 2009-08-04, had a primary completion date of 2018-02-28, and is listed as terminated.

The primary endpoint is the chronic left ventricular lead-related complication-free rate, expressed as percent free from event with a 95% confidence interval. Its timeframe runs from enrollment to study completion, with five-year follow-up, withdrawal or death specified. The numeric endpoint result, confidence interval, endpoint definition and analysis details are not reported in the registry record.

The “Implants” adverse-event group lists 1303 at risk, 117 affected by serious adverse events, 131 affected by other adverse events, and 269 deaths. The record does not state a like-for-like control comparison, and its adverse-event details do not establish causation.