TOCCATA - Touch+™ for Catheter Ablation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for TOCCATA - Touch+™ for Catheter Ablation (NCT01223469), a non-randomized na study. The primary outcome is Number of Subjects With Operative and Post-operative Serious Adverse Events.

2. Clinical Question

3. Trial Design

TOCCATA is a prospective, multi-centre clinical investigation of a contact force sensing irrigated ablation catheter. The registry identifies its design as parallel and its allocation as non-randomized. It lists no masking. The study is marked as completed, with phase recorded as NA. The record gives enrollment as 77 and identifies Abbott Medical Devices as the sponsor.

The trial began in 2008-09, and primary completion is recorded as 2010-02. The two listed clinical groups are atrial fibrillation and right-sided supraventricular tachycardia. Because the groups have different conditions and different primary outcome observation periods, their event counts should not be read as results from equivalent treatment arms. There is no randomized allocation to make them comparable as intervention and control groups.

The study objective centers on clinical safety of the catheter when used for treatment of supraventricular tachycardia and atrial fibrillation. It also aims to characterize use and value of contact force measurement and long-term success at 12 months. The intervention listed is contact force assisted irrigated RF ablation. The registry record does not report additional study procedures, protocol details, or a comparator intervention.

Enrollment and completion status describe the study record, not the completeness of the outcome data. Detailed participant flow, exclusions from analysis, baseline characteristics and the analysis populations are not reported in the registry record. Those omissions limit the ability to assess whether the reported event counts represent all enrolled participants or a defined subset. The non-randomized, unmasked design also means that the record does not support a controlled estimate of the catheter’s effect relative to another approach.

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 Subjects With Operative and Post-operative Serious Adverse Events, measured over 3 months for AF arm; 7 days for the right SVT arm.

The primary outcome counts participants with operative and post-operative serious adverse events. It is a safety endpoint: it records whether a serious event was reported during a specified period around the ablation procedure, rather than measuring a change in symptoms, rhythm status or another effectiveness outcome. The outcome title specifies participants with events, and the unit is participants.

The observation periods differ by clinical group. For the atrial fibrillation arm, the stated period is 3 months, with the description specifying 3 months (±2 weeks) following the index procedure. For the right-sided supraventricular tachycardia arm, the stated period is 7 days, with the description specifying 7 days (±1 day) following the index procedure or until hospital discharge, whichever is longer. These differences matter when reading the group counts: the time available to capture events is not the same.

Safety outcomes are useful in a device investigation because they describe harms observed during and after the procedure. However, a count alone does not establish the cause of an event, its severity beyond the registry classification, or whether the device changed the risk. The registry record does not report a definition of serious adverse event or further adjudication details. It also does not report an effectiveness outcome measure among the listed outcome measures, even though long-term success is mentioned as an objective.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

For a binary safety outcome, each participant is classified according to whether the event was recorded during the defined observation period. The registry describes the primary result as a number of participants with serious adverse events. Counts are straightforward to read, but their meaning depends on the outcome definition, the number at risk, follow-up duration and completeness of outcome collection. The record gives at-risk counts and affected-participant counts for the listed groups, but does not report detailed rules for event classification or data completeness.

Why are the event counts descriptive?

A descriptive count reports what was observed in the study groups. A comparative treatment effect requires a suitable contrast between groups, usually with comparable eligibility, follow-up and outcome measurement. Here, allocation is non-randomized, the groups have different diagnoses, and the endpoint observation periods differ. The groups are not a like-for-like control comparison. A crude comparison would mix any treatment-related differences with differences in group composition, clinical context and event observation.

Randomization, in general, is used to reduce systematic differences between treatment groups by assigning participants by chance. This record does not describe randomized allocation. Masking can reduce some forms of bias in outcome assessment or participant reporting; the registry lists masking as none. The record does not explain whether event assessors followed standardized procedures or whether serious events received independent review. These are general design considerations, not claims about procedures that the registry does not describe.

What does a confidence interval add?

In general, a confidence interval expresses the statistical uncertainty around an estimate. A narrow interval indicates greater precision under the assumptions of the method, while a wide interval indicates less precision. It does not guarantee that the estimate is unbiased, and it cannot correct for non-comparable groups or incomplete outcome reporting. No confidence intervals are reported in the registry record for the serious adverse event results, so the precision of the group counts cannot be assessed using that information.

Hypothesis tests and adjusted models can address specific questions, but their interpretation depends on a prespecified analysis plan, model assumptions and suitable data. The registry record lists no analyses. It does not report a statistical analysis plan, adjustment variables, hypothesis tests, interim analyses or a rationale for the enrollment target. Those items cannot be inferred from the observed counts.

Why do follow-up windows matter?

An event can only be captured if it occurs and is ascertained within the defined observation period. The record specifies 3 months (±2 weeks) following the index procedure for atrial fibrillation participants. For right-sided supraventricular tachycardia participants it specifies 7 days (±1 day) or until hospital discharge, whichever is longer. The periods differ in duration and in their discharge-related rule. That affects what each count represents and limits direct comparison between groups. The registry does not report event timing within those periods.

How should planning illustrations be read?

General sample-size calculations estimate how many participants may be needed to detect a specified effect under stated assumptions. They are planning illustrations, not evidence about the number of participants actually needed under the trial’s true conditions and not a measure of observed power. The planning description associated with this study uses a two-sided significance level of 0.05, equal allocation between the arms and a normal approximation, with effects defined as fractions of the observed effect. It states that non-time-to-event illustrations are expressed as participants per arm. The registry does not report that these were the trial’s design assumptions, and the trial itself is described as non-randomized. The record does not give a sample-size justification or explain the selection of the observed effect used in those illustrations.

Over-dispersion is a general concern when counts vary more than a statistical model expects; ignoring it can make uncertainty appear too small. It is not possible to assess over-dispersion from the reported participant-level binary event counts alone, and no model-based analysis is reported. More broadly, the registry’s limited analysis information means that descriptive reading is more defensible than drawing conclusions from an unreported inferential framework.

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("Atrial Fibrillation", "Right-sided Supraventricular Tachycardia")
n      <- c(34, 43)
events <- c(4, 1)
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  Atrial Fibrillation  34  4  11.8  3.3  27.5  4.7  26.6  4.8  26.7
ARM  Right-sided Supraventricular Tachycardia  43  1  2.3  0.1  12.3  0.4  12.1  0.6  12.0

11. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when several outcomes, comparisons or statistical tests are examined: the more questions tested, the greater the chance of at least one apparently notable result by chance. The registry lists one outcome measure, the number of participants with operative and post-operative serious adverse events. It does not report a multiplicity adjustment or explain whether additional outcomes or analyses were planned outside the listed record. The stated objectives include long-term success and characterization of contact force measurement, but corresponding outcome measures are not listed in the outcome information. Without a documented analysis plan, it is not possible to determine how these objectives were evaluated or whether multiple testing was considered.

Missing-data handling is also not reported in the registry record. It does not give participant flow, numbers with incomplete follow-up, reasons for missing outcomes, or procedures for handling missing observations. The reported at-risk counts identify group denominators for the adverse-event figures, but do not by themselves establish that all participants completed the relevant observation period or had outcome status known.

The analysis populations are not described. The record does not state whether results use all enrolled participants, participants who received the procedure, or another defined group. It also does not report exclusions or deviations from the intended procedure. Consequently, readers cannot assess how missing data or analysis-set choices might affect the reported counts. These omissions do not prove that data were missing; they mean the registry record does not report enough information to evaluate that possibility.

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 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: sinus bradycardia (2.9%), tamponade (2.9%), groin bleeding (2.9%), stroke (2.9%).

The serious adverse event results list 4 affected participants among 34 at risk in the atrial fibrillation group and 1 among 43 at risk in the right-sided supraventricular tachycardia group. The registry also lists 0 participants affected by other adverse events in each group. Death information is not reported in the registry record. The listed serious-event terms are Sinus Bradycardia, Tamponade, Groin Bleeding and Stroke, each recorded as 2.9%.

These numbers describe reported events in the study groups; they do not establish that the device caused an event or that it prevented one. The registry does not provide detailed event narratives, severity grading beyond the serious classification, timing, relatedness assessment or adjudication procedures. Nor does it clarify whether the term-level percentages count unique participants or events. Do not sum the term frequencies to infer a total number of participants, since terms may not correspond to separate people.

Follow-up differs between the groups: 3 months for atrial fibrillation and 7 days for right-sided supraventricular tachycardia, with the latter extending to discharge if longer. The counts therefore arise from different windows for detecting events. With no randomized control group or reported uncertainty estimates, these figures are descriptive safety observations rather than a comparative estimate of risk.

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

The registry record documents a prospective, multi-centre device investigation with a primary safety outcome and reports serious adverse event counts for atrial fibrillation and right-sided supraventricular tachycardia groups. It also lists several serious-event terms and reports no affected participants for other adverse events in the group summaries. These observations are useful for understanding what the registry recorded during the specified follow-up periods.

They do not demonstrate that the catheter caused or prevented any event. The trial is non-randomized, unmasked and has no like-for-like control comparison in the listed arms. The groups have different diagnoses and different follow-up windows. The record also lacks reported confidence intervals, adjusted comparisons, a statistical analysis plan and details of outcome completeness. Those limitations prevent a precise comparative interpretation of the counts.

The record’s objectives include long-term procedural success and evaluating the use and value of contact force measurement. However, the listed outcome measure is the count of participants with operative and post-operative serious adverse events. A stated objective is not itself a reported result: the registry information does not provide a listed long-term success result or an analysis of contact force measurement’s value. No conclusion about effectiveness should be drawn from the safety counts alone.

Enrollment of 77 and completed status describe the registered study, but they do not resolve questions about which participants were included in each analysis or whether follow-up was complete. The results should therefore be read as registry-reported event observations in the listed groups, not as proof of comparative safety, effectiveness or generalizability to patients outside the study. Additional protocol and analysis information would be needed to assess those questions.

14. Why This Trial Matters Statistically

This trial illustrates why a safety count cannot be interpreted in isolation. Event counts have meaning only alongside their denominators, follow-up periods, outcome definitions and study design. The registry gives group-specific counts and at-risk numbers, but the groups have different conditions and different windows for identifying events. Those features make a direct comparison potentially misleading even before considering uncertainty.

The non-randomized design is especially important for biostatistical interpretation. When groups are not assigned at random and are not intended as equivalent controls, observed differences can reflect who entered each group, the clinical condition being treated, or how long events were monitored. The registry does not report an adjusted analysis that might address measured differences, and adjustment would not automatically resolve unmeasured differences.

The record also demonstrates the distinction between study objectives and reported outcomes. Safety is represented by a listed outcome measure, while long-term success and contact force characterization appear as objectives without corresponding outcome measures in the registry information. That distinction matters when evaluating whether the posted results answer the questions a study set out to address.

Finally, the registry lacks key information needed to judge precision and robustness: confidence intervals, analysis populations, missing-data handling and a statistical analysis plan are not reported. The figures can still be described accurately, but their evidential reach is limited. Recognizing those limits is central to reading registry results responsibly, particularly when a study has no randomized comparator and when the clinical groups differ.

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.

Several limitations are specific to this record. The study is non-randomized and unmasked, and the listed groups are not a like-for-like comparison. Atrial fibrillation and right-sided supraventricular tachycardia are separate clinical groups, not treatment and control arms. The serious adverse event observation windows also differ: the record specifies 3 months for the atrial fibrillation group and 7 days or until discharge if longer for the right-sided supraventricular tachycardia group.

The registry record does not report detailed eligibility criteria, baseline characteristics, participant flow, outcome completeness, event definitions or adjudication procedures. It does not report confidence intervals, adjusted estimates, hypothesis tests, analysis populations, missing-data methods, interim analyses or a statistical analysis plan. A sample-size justification is not reported in the registry record. The record’s planning assumptions are described as illustrations based on the observed effect rather than as the study’s own design justification.

Although the study objectives include long-term success and characterization of contact force measurement, the listed outcome measure concerns serious adverse events. Corresponding effectiveness results and details of how contact force measurement was evaluated are not reported among the listed outcome information. The registry also does not explain whether the term-level event percentages refer to unique participants or events. These limitations restrict conclusions to a descriptive account of the registered safety figures, without a causal or comparative interpretation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: TOCCATA - Touch+™ for Catheter Ablation — NCT01223469.
• Registry record last updated 2019-01-30; status last verified 2019-01.
• Results first posted 2014-06-03.
• 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

TOCCATA is a completed, prospective, multi-centre investigation of contact force assisted irrigated RF ablation using the TactiCath™ catheter. The registry lists non-randomized allocation, no masking, a parallel model, phase NA and enrollment of 77. The study began in 2008-09, with primary completion in 2010-02.

The listed groups are atrial fibrillation and right-sided supraventricular tachycardia. The primary outcome counts participants with operative and post-operative serious adverse events, with different observation periods for the groups. The posted adverse-event figures include 4 affected participants among 34 at risk for atrial fibrillation and 1 among 43 at risk for right-sided supraventricular tachycardia. No inferential analyses are listed in the registry record. Because the study is non-randomized and the groups and follow-up differ, the counts are descriptive rather than a controlled comparison.