Clinical Evaluation of the Blazer® Open-Irrigated Catheter for Treatment of Type 1 Atrial Flutter: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of the Blazer® Open-Irrigated Catheter for Treatment of Type 1 Atrial Flutter (NCT01253200), a randomized na study. The primary outcome is Procedure-related Complication-free Rate.

2. Clinical Question

3. Trial Design

The registry record describes a completed, randomized, single-masked, parallel-group device study sponsored by Boston Scientific Corporation. The phase is listed as NA. Total enrollment was 302. Participants were assigned to the Blazer® Open-Irrigated Ablation Catheter or a control catheter; the control was an open-irrigated radiofrequency ablation catheter with FDA market approval for treatment of type 1 atrial flutter. The registry record names several control-device models.

The primary outcome was analyzed in a subset of randomized subjects who underwent radiofrequency ablation. The registry describes this population as 220 subjects out of the total 302. The primary result therefore does not represent every enrolled participant. The posted primary arm sizes were 109 for Blazer® and 111 for control. The record also includes roll-in groups and a group not randomized to a treatment group in its adverse-event listings; those groups are distinct from the randomized primary comparison.

The registry lists chronic success among the secondary outcomes, assessed at 3 months post-procedure. It reports chronic success for all treated patients and for acute-success patients, although results for the latter are not included in the posted outcome details used for this interpretation. The record lists four outcome measures and one analysis. Further details about allocation procedures, who was masked, treatment delivery, follow-up procedures, and the trial’s original sample-size rationale are not reported in the registry record.

The trial began in 2011-01, had primary completion in 2013-09, and is marked completed. These dates describe the registry record; they do not, by themselves, establish when all analyses were finalized or whether the record contains every analysis conducted.

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.

Before assignment: Subjects were excluded if there were no documented episodes of atrial flutter or inclusion criteria were not met. Roll-in subjects were not randomized.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The primary outcome analysis is for a further subset of Randomized subjects only who underwent RF ablation; 220 subjects out of the total 302 subjects. All is consistent with the approved statistical analysis plan and information publicly available in the FDA Summary of Safety and Effectiveness Data (SSED) and BSC labeling, the Directions for Use.

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 Procedure-related Complication-free Rate, measured over 7 days post-procedure.

The primary endpoint is the procedure-related complication-free rate, expressed as the percentage of subjects without a qualifying complication through 7 days post-procedure. The registry defines procedure-related complications to include adverse events related to the investigational or control device or the ablation procedure that resulted in death, a life-threatening complication, persistent or significant disability or incapacity, or an intervention required to prevent permanent impairment of a body function or damage to a body structure.

This kind of endpoint summarizes an important safety outcome over a specified short-term period. A percentage is readily interpretable as the proportion of the analyzed group meeting the endpoint, but it does not describe the severity or timing of every event, nor does it capture outcomes outside the stated follow-up window. The registry reports 92.7% for the Blazer® group and 98.2% for the control group. Those percentages are based on the primary analysis population, described as randomized subjects who underwent radiofrequency ablation, rather than all 302 enrolled subjects.

The registry record does not provide a confidence interval alongside the arm percentages. The separate recalculated comparison gives a risk difference and confidence interval, which express the estimated contrast and its uncertainty. The endpoint definition and the follow-up window are essential to interpreting the result: it concerns a defined set of procedure-related events within 7 days, not all possible safety outcomes or longer-term risks.

7. Results Posted in the Registry

• Blazer® Open-Irrigated Ablation Catheter: 92.7% (101/109) versus 98.2% (109/111) on control; risk difference -5.5 percentage points (95% CI -11.0 to -0.1), risk ratio 0.94 (0.89–1.00); unadjusted two-proportion z-test p = 0.049.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Chronic Success Rate: All Treated Patients

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Blazer® Open-Irrigated Ablation Catheter: 74.3% (81/109) versus 80.2% (89/111) on control; risk difference -5.9 percentage points (95% CI -16.9 to 5.2), risk ratio 0.93 (0.80–1.07); unadjusted two-proportion z-test p = 0.299.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Blazer® Open-Irrigated Ablation Catheter and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes concern chronic success after the procedure, rather than the short-term complication-free primary endpoint. For all treated patients, the recalculated comparison points in the same broad direction as the primary contrast under the Blazer®-relative-to-control convention, but its confidence interval includes zero and its unadjusted p-value is 0.299. The registry record names chronic success among acute-success patients as another secondary outcome, but does not post its results in the details available for interpretation.

These outcomes address different aspects and time points of treatment. A short-term procedure-related complication endpoint and a later chronic-success endpoint should not be treated as interchangeable measures. The pattern across the available results is therefore descriptive: the primary comparison favors control in complication-free status, while the available secondary comparison is less precise and does not rule out differences in either direction. It does not establish a unified treatment effect across safety and success outcomes.

Unadjusted secondary results carry less weight as confirmatory evidence when the analysis plan, multiplicity strategy, and prespecified hierarchy are not reported. General statistical explanation: when several outcomes are examined, the chance of at least one apparently notable result can increase unless the inferential plan accounts for multiple comparisons. The registry lists four outcome measures, but does not report how multiplicity was handled, whether each secondary analysis was prespecified, or which outcomes were intended to support a formal claim.

Accordingly, the secondary findings can add context to the primary endpoint but should not be used to reverse, validate, or extend the primary result. The record does not provide enough information to determine whether the secondary outcomes were powered for confirmatory comparisons, and their interpretation remains limited by the available analysis details.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Chronic Success Rate: All Treated Patients
• Chronic Success Rate: Acute Success Patients

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is binary: each subject either met the definition of complication-free status through the stated follow-up or did not. The registry expresses the result as a percentage of subjects. General statistical explanation: a group percentage describes the observed proportion in that group, while a comparison statistic summarizes how the proportions differ between groups. A risk difference is the first group’s event proportion minus the comparator’s event proportion, according to the stated group order. Here, the recalculated contrast is expressed as Blazer® relative to control, so a negative risk difference corresponds to a lower complication-free proportion in the Blazer® group.

The recalculated primary risk difference is -0.055. Its 95% confidence interval is -0.110 to -0.001. General statistical explanation: a confidence interval gives a range of values reasonably compatible with the observed data under the assumptions of the method. It reflects sampling uncertainty, not uncertainty about every feature of trial conduct or the correctness of the endpoint definition. An interval that approaches zero suggests that small contrasts are compatible with the data; an interval that remains on one side of zero indicates that the estimated direction is consistent across the interval. Clinical importance still requires a prespecified interpretation threshold, which is not reported for the recalculated comparison.

The recalculated p-value is unadjusted and equals 0.049. General statistical explanation: a p-value measures how unusual data at least as extreme as those observed would be under a specified null model. It is not the probability that the null hypothesis is true, and it does not quantify the size or importance of an effect. Its interpretation depends on the statistical method, analysis population, and whether the analysis was planned in advance. The registry record does not identify the method used for the sponsor’s posted analysis or provide a complete statistical analysis plan.

The registry’s sponsor-reported result is labeled as a risk-difference non-inferiority or equivalence analysis. That type of analysis ordinarily relates an estimated difference and its uncertainty to a prespecified margin. General statistical explanation: a non-inferiority assessment asks whether the data rule out a loss larger than an acceptable margin, while an equivalence assessment asks whether the data are sufficiently compatible with differences inside a prespecified range. The margin, direction convention, method, and lower confidence bound for the sponsor’s reported result are not reported in the registry record. Without those details, the label and posted upper bound alone do not establish whether a formal criterion was met.

The posted arm values for the primary endpoint are 92.7% and 98.2%. The recalculation uses the posted group counts and event information described in the record. The registry labels the analysis population as randomized subjects who underwent radiofrequency ablation, and the displayed arm sizes are 109 and 111. General statistical explanation: unadjusted comparisons use the observed group summaries without adjusting for other covariates. Such comparisons are straightforward, but they do not account for any imbalances in prognostic characteristics that might remain after randomization, nor do they reproduce a prespecified adjusted analysis if one was used.

The same general framework applies to the posted secondary chronic-success outcome for all treated patients. Its recalculated risk difference is -0.059, with a 95% confidence interval from -0.169 to 0.052 and an unadjusted p-value of 0.299. The interval includes zero, so the data are compatible with differences in either direction under this unadjusted comparison. General statistical explanation: a wider interval indicates less precision, which can arise from limited information or variability in the observed outcome. The registry does not post a sponsor analysis for this secondary endpoint.

Binary outcome methods rely on assumptions about independent observations and the way outcomes are classified and followed. General statistical explanation: if participants’ outcomes are correlated, or if outcome ascertainment differs across groups, simple comparisons may not fully reflect the uncertainty or potential bias. The registry record does not describe adjustments for clustering, covariates, missing data, or deviations from randomized assignment. These details should not be inferred from the reported estimates.

The sample-size illustrations are based on observed effects and stated planning assumptions, rather than the original trial design. General statistical explanation: power is the probability that a specified analysis will identify an effect of a specified size under its assumptions. A planning calculation asks how many participants might be needed for a target power under those assumptions; it does not describe the probability that the completed trial’s result is correct. The original design assumptions, including any design-stage effect size or sample-size justification, are not reported in the registry record.

11. Confidence Intervals and Precision

The recalculated primary contrast has a 95% confidence interval from -0.110 to -0.001. The interval lies on the negative side of zero but approaches zero closely. Under the stated contrast convention, the range is consistent with a smaller difference favoring control in complication-free status as well as a more pronounced difference. The endpoint percentages alone do not show this uncertainty; the interval adds information about the range of contrasts compatible with the observed data and calculation.

A confidence interval is not a guarantee that the true effect lies within its endpoints, and it does not incorporate all possible sources of uncertainty. General statistical explanation: its interpretation relies on the statistical model and sampling assumptions used to construct it. The registry record does not give the sponsor’s method or full analysis plan, and the recalculated interval is unadjusted. The estimate also concerns the primary analysis subset, not every enrolled participant.

The secondary chronic-success comparison is less conclusive in direction: its 95% confidence interval ranges from -0.169 to 0.052 and crosses zero. This interval allows for possible differences in either direction under the recalculated comparison. It should not be read as evidence that the groups are identical. Rather, the observed data do not yield a narrow interval confined to one side of zero.

For the sponsor’s primary analysis, the registry reports a 95% confidence interval and an upper bound of 9.78, but no lower bound. The reported value is 4.6. Without the missing bound, the margin, and the direction convention, the precision and decision rule for that analysis cannot be fully assessed from the registry record. Confidence intervals address statistical precision, while clinical relevance depends on the size and consequences of the outcome difference and on a justified threshold.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are illustrations based on the observed effect, not the trial’s original design calculation. For these binary outcomes, the entries are participants per arm, rather than total events. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect. The original trial’s own sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the planned participants per arm under those assumptions for an analysis with an 80% chance of detecting the specified effect, if that effect and the assumptions are correct. The 90% power column applies the same idea at a higher target probability of detection. These are hypothetical planning targets, not properties measured from the completed trial. This is not observed power.

Rows labeled as planning for 100%, 75%, or 50% of the observed effect change the effect size the calculation is intended to detect. Smaller effects require more participants to distinguish them from sampling variation at the same target power and significance level. The resulting figures can therefore increase substantially as the assumed effect is reduced. They should be read as conditional planning illustrations, not as recommendations or evidence that the trial was adequately or inadequately designed.

The curve is another way to understand the relationship between assumptions and required sample size: the required number depends on the effect size and target power, along with the stated calculation assumptions. Neither the curve nor the planning figures show the chance that a treatment effect is real, and neither can substitute for the trial’s original protocol or statistical analysis plan.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.982; treatment proportion p₁ = 0.927; average p̄ = 0.954.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.2954 = 0.5789.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.2927 = 0.2464.
4. n = (0.5789 + 0.2464)² / (-0.0554)² = 222.1, rounded up to 223 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.981981981981982                          # control proportion
p1 <- 0.926605504587156                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1253200)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 223 (80% power), 297 (90% power)
 75% of observed effect: n per arm = 339 (80% power), 453 (90% power)
 50% of observed effect: n per arm = 631 (80% power), 844 (90% power)
power.prop.test: 222.1 
Simulated power at n = 223 per arm: 0.830 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry reports a sponsor analysis of the primary endpoint labeled as a risk-difference non-inferiority or equivalence analysis. The reported value is 4.6, with a 95% confidence interval whose upper bound is 9.78. The lower confidence bound and a p-value are not posted. The registry record also does not state the analysis method, the direction convention for the difference, or the prespecified margin needed to interpret a non-inferiority or equivalence assessment.

The recalculated comparison is an unadjusted risk difference based on the posted summary statistics. It is -0.055, with a 95% confidence interval from -0.110 to -0.001 and an unadjusted p-value of 0.049, using Blazer® relative to control. These two presentations are not fully comparable from the registry entry alone: the sponsor result has a different reported value format, lacks one interval bound, and does not specify its direction convention or method. No conversion or alignment of the estimates can be established from the posted details.

The registry record does not say whether the sponsor’s analysis used a particular adjustment, analysis population, or imputation approach. The sponsor result should therefore be read as the reported non-inferiority or equivalence analysis, while the recalculation should be read as a separate unadjusted comparison of posted summaries. The missing margin and analysis details prevent a complete assessment of the sponsor’s decision rule.

15. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a multiplicity adjustment or a testing hierarchy for the outcome analyses. It lists four outcome measures and two secondary chronic-success outcomes, while the posted details include one secondary comparison. General statistical explanation: testing several outcomes can make an isolated small p-value less persuasive as confirmatory evidence, because the chance of finding at least one apparently unusual result may increase. Whether an adjustment is appropriate depends on the planned claims and analysis strategy, which are not reported.

Details about missing outcome data are not reported in the registry record. The record does not state how many participants lacked primary or secondary outcome assessments, how missing outcomes were handled, or whether sensitivity analyses were conducted. General statistical explanation: missing outcomes can affect both the estimated event proportions and the uncertainty around a comparison, particularly if missingness differs between groups or relates to outcome status. The posted results alone cannot establish that missing data had no effect.

The primary population is described as randomized subjects who underwent radiofrequency ablation, a subset of the 302 enrolled subjects. The record does not fully describe how participants who did not undergo ablation were handled in other analyses, whether the primary analysis followed intention-to-treat principles, or how protocol deviations were addressed. Those details matter because analysis populations can answer different questions and may produce different estimates.

The registry record does not report a complete statistical analysis plan, the sponsor’s analysis method, covariate adjustment, non-inferiority margin, or prespecified handling of interim analyses. Interim analyses are not reported in the registry record. These omissions limit assessment of whether the posted estimates match the intended analysis and whether the inferential thresholds were set before outcomes were examined. They do not establish that such methods were or were not used; they indicate that the registry entry does not document them.

16. 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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: 3rd degree heart block (8.3%), sinus bradycardia (8.3%), atrial fibrillation (7.1%), chest pain iscemic (3.6%), myocardial perforation with tamponade (3.6%).

For the randomized Blazer® group, the registry lists 7 subjects affected by serious adverse events among 109 at risk; for the randomized control group, it lists 2 among 111 at risk. The record lists 1 death in the randomized Blazer® group and 0 in the randomized control group. Other adverse events are listed for 50 of 109 in the randomized Blazer® group and 61 of 111 in the randomized control group. These are descriptive registry counts and are not the same measure as the primary procedure-related complication-free rate.

The registry also lists serious adverse events in roll-in groups and in a group not randomized to treatment. Those groups should not be combined with the randomized comparison when interpreting the randomized groups. The record identifies several serious-event terms, including 3rd Degree Heart Block, Sinus Bradycardia, and Atrial Fibrillation, with percentages attached to the listed terms. The registry does not provide enough detail in this summary to interpret those term-specific percentages as comparative risks between randomized arms.

Serious adverse-event counts do not, on their own, establish causality or comparative safety. The number affected, event definitions, follow-up, and any relatedness assessment all matter. The registry describes the primary endpoint’s procedure-related definition separately; the serious adverse-event listings should not be assumed to use that same definition.

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

The posted primary data describe complication-free status through 7 days after the procedure in randomized subjects who underwent radiofrequency ablation. The observed percentage was lower in the Blazer® group than in the control group, and the recalculated unadjusted risk difference was negative with a confidence interval that approaches zero. This is evidence about the recorded endpoint in the analyzed subset, not a complete account of all clinical outcomes or all enrolled participants.

The result does not establish that one catheter is clinically preferable. The registry record does not provide a threshold for a clinically important difference, and the sponsor’s non-inferiority or equivalence margin is not reported. The sponsor’s posted analysis lacks a lower confidence bound and method details, so a formal conclusion under its stated framework cannot be independently evaluated from the registry entry alone.

The result also does not show that the groups are identical when a confidence interval includes zero, as in the available secondary comparison. Such an interval indicates uncertainty across a range of possible differences. Conversely, a p-value near a conventional threshold does not establish that an observed difference is important, causal in every relevant population, or robust to all analytic choices.

The trial concerns a specific device comparison and defined outcomes. It does not address every ablation device, every patient group, every complication, or longer-term outcomes beyond those listed. The primary outcome window is 7 days post-procedure, and the posted chronic-success outcome is assessed at 3 months post-procedure. The registry does not provide the details needed to assess longer follow-up or every dimension of safety and effectiveness.

These findings are statistical descriptions of the registry results, not medical advice. Decisions about treatment require broader clinical evidence and individual assessment beyond the estimates posted in this record.

18. Why This Trial Matters Statistically

This trial is statistically notable because it compares a device with a control catheter in a randomized, parallel-group design and reports a short-term binary safety endpoint. Randomization can support a fair group comparison when allocation and follow-up are implemented well, but the registry record does not give enough operational detail to assess those processes fully. The primary analysis population is also narrower than total enrollment, making clarity about who contributes to an estimate important.

The endpoint illustrates why absolute group summaries, contrast estimates, and uncertainty should be read together. The arm percentages communicate the observed complication-free proportions; the recalculated risk difference expresses their contrast; and the confidence interval shows that the estimate is not perfectly precise. A single p-value cannot replace these elements or establish the clinical importance of the result.

The record also presents a sponsor analysis labeled non-inferiority or equivalence alongside an unadjusted recalculation. These approaches answer related but not identical statistical questions. A non-inferiority or equivalence claim depends on a prespecified margin and an analysis method, neither of which is documented in the registry entry. This highlights the importance of a transparent protocol and statistical analysis plan when interpreting device-comparison trials.

Finally, secondary outcomes and adverse-event summaries contribute context, but they are not interchangeable with the primary endpoint. The registry does not report multiplicity handling, missing-data methods, or the original sample-size rationale. Statistical interpretation therefore depends not only on the estimates, but also on population definitions, endpoint timing, analysis choices, and the limits of what the record documents.

19. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

Several limitations specific to this trial affect interpretation. The primary endpoint is restricted to randomized subjects who underwent radiofrequency ablation, described as 220 of the 302 enrolled subjects. The registry does not provide a complete account of participants excluded from that analysis, the reasons they were excluded, or their outcomes. The primary result therefore should not be treated as an estimate for all enrolled participants without further information.

The outcome is a composite definition of procedure-related complications over 7 days. The registry gives the qualifying severity criteria, but the posted summary does not provide a complete breakdown of primary-endpoint events by type or severity. The short follow-up window also means this endpoint does not describe longer-term complications.

The sponsor’s analysis is labeled non-inferiority or equivalence, but the registry does not report the margin, method, lower confidence bound, or p-value. This limits evaluation of the sponsor’s formal inferential claim. The recalculated estimate is unadjusted and should not be assumed to reproduce the sponsor’s analysis.

The record does not document multiplicity handling, missing-data methods, the full analysis population for each outcome, or the trial’s original sample-size justification. Only one of the two named secondary chronic-success outcomes has posted results in the available details. Adverse-event counts are descriptive, and the summary does not establish that listed events were caused by a device or procedure. These limits reflect the information recorded in the registry and do not establish what analyses or procedures may have been conducted outside it.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Clinical Evaluation of the Blazer® Open-Irrigated Catheter for Treatment of Type 1 Atrial Flutter — NCT01253200.
• Registry record last updated 2018-03-19; status last verified 2018-02.
• Results first posted 2018-02-15.
• 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.

23. Record Summary

NCT01253200 is the completed BLOCk-CTI study, a randomized, single-masked, parallel-group evaluation of the Blazer® Open-Irrigated Ablation Catheter against an FDA-approved open-irrigated control catheter for type 1 atrial flutter. Total enrollment was 302. The primary endpoint was procedure-related complication-free status at 7 days post-procedure, analyzed in randomized subjects who underwent radiofrequency ablation.

The posted primary complication-free rates were 92.7% for Blazer® and 98.2% for control. The recalculated unadjusted risk difference was -0.055, with a 95% confidence interval from -0.110 to -0.001 and an unadjusted p-value of 0.049. The sponsor’s separate result is labeled non-inferiority or equivalence, but the registry record omits details needed to fully assess that analysis. Available secondary and safety results provide additional context, with important limitations in analysis and reporting detail.