This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for REnal Sympathetic dEnervaTion as an a Adjunct to Catheter-based VT Ablation (NCT01858194), a randomized na study. The primary outcome is Freedom From First Event Requiring ICD Therapy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01858194 |
| Phase | NA |
| Condition | Ventricular Tachycardia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 21 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Vivek Reddy |
| Results posted | Yes |
2. Clinical Question
Population
Patients with ischemic or non-ischemic ventricular dysfunction who were to receive catheter-based ventricular tachycardia (VT) ablation. The study description focuses on preventing subsequent implantable cardioverter-defibrillator (ICD) therapy in this population.
Intervention
Renal sympathetic denervation (RSDN) by catheter-based ablation, added to VT ablation. The record describes this as adjunctive treatment and names the intervention arm “Renal Sympathetic Denervation.”
Comparator
VT ablation alone, with no further therapy in addition to VT ablation. The comparison therefore concerns the addition of RSDN, rather than RSDN as a substitute for VT ablation.
Primary question
What is the probability of remaining free from a first event requiring ICD therapy at 12 months and at 24 months? The registry describes this as the primary endpoint. Numerical probabilities and a comparative estimate between the randomized groups are not reported in the registry record, so the posted information does not establish the size or precision of any difference.
The trial addresses recurrence after an ablation procedure in a clinical setting where the registry description identifies continuing challenges in preventing VT and associated ICD therapies. Its primary endpoint is framed around the first subsequent event requiring ICD therapy. Other listed outcomes include ICD shocks and therapies, VT burden, mortality, hospitalizations for cardiovascular causes, ICD storm, and incessant VT. These additional outcomes broaden the clinical questions recorded, but their numerical results are not reported in the registry record.
3. Trial Design
The registry describes a randomized, single-masked, parallel-group study. Participants were assigned to renal sympathetic denervation or VT ablation alone. The record reports enrollment of 21 and a completed status. The start is recorded as 2013-03, and primary completion as 2017-09-01.
The intervention was catheter-based renal sympathetic denervation added to catheter-based VT ablation. In the comparator arm, the description is no further therapy in addition to VT ablation. The registered condition is ventricular tachycardia. The study description identifies patients with ischemic or non-ischemic ventricular dysfunction who were to receive VT ablation as the intended clinical population.
“Randomized” indicates that assignment was intended to use chance rather than being chosen solely by clinicians or participants. A parallel design compares groups followed under their assigned strategies. “Single” is the registry’s masking classification, but the record does not identify which participants, clinicians, outcome assessors, or other personnel were masked. It also does not report the randomization sequence method, allocation concealment, or procedures for maintaining masking. Those details should not be inferred from the design labels.
The primary outcome is described as the probability of freedom from a first event requiring ICD therapy, with assessments specified at 12 months and 24 months. The primary timeframe is recorded as 24 months. Although the record lists secondary outcome categories and an outcome-measure count, it provides no numerical primary-outcome estimates or comparative analysis in the posted information. Details of follow-up procedures, the analysis population, and the statistical plan are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | VT Ablation Alone | Renal Sympathetic Denervation |
|---|---|---|
| STARTED | 8 | 9 |
| COMPLETED | 8 | 7 |
| NOT COMPLETED | 0 | 2 |
Reasons for not completing this period:
| Reason | VT Ablation Alone | Renal Sympathetic Denervation |
|---|---|---|
| Total Artificial Heart Implant | 0 | 1 |
| Lost to Follow-up | 0 | 1 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | VT Ablation Alone | Renal Sympathetic Denervation | Total |
|---|---|---|---|---|
| Participants analysed | 8 | 9 | 17 | |
| Age, Continuous | years | 61.5 (SD 8.73) | 56.78 (SD 9.43) | 58.88 (SD 9.12) |
| Sex: Female, Male: Female | Participants | 1 | 1 | 2 |
| Sex: Female, Male: Male | Participants | 7 | 8 | 15 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 1 | 3 | 4 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 7 | 6 | 13 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 1 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 3 | 1 | 4 |
| Race (NIH/OMB): White | Participants | 3 | 7 | 10 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 2 | 0 | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Freedom From First Event Requiring ICD Therapy, measured over 24 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | probability of freedom |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the probability of remaining free from a first event requiring ICD therapy, described for 12 months and 24 months. It focuses on the time until a participant first experiences an event that meets the endpoint definition, rather than on the total number of events over follow-up. Once a first qualifying event occurs, later events do not change the status of that first-event endpoint, although they may be captured by other outcomes.
In general, a freedom-from-event probability expresses the proportion of a population expected to remain without the specified event through a stated follow-up time. It is useful when the timing of the first event matters and participants may have different lengths of observation. Such an analysis must account for how follow-up ends for participants who have not had the event; the specific method used for this trial is not reported in the registry record.
The endpoint connects to the study’s stated objective of evaluating prevention of ICD therapy after VT ablation. Its interpretation depends on the exact definition of a qualifying event, how events were adjudicated, and how incomplete follow-up was handled. Those details are not reported in the registry record. The record identifies the endpoint and its time points but does not provide the numerical probabilities, a treatment-group contrast, confidence intervals, or a test result. Therefore the endpoint description alone cannot show how the groups compared or how precisely any comparison was estimated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a randomized comparison of renal sympathetic denervation added to VT ablation versus VT ablation alone. It also names freedom from a first event requiring ICD therapy as the primary endpoint and specifies assessments at 12 months and 24 months. However, numerical results for this endpoint are not reported in the registry record. No comparative estimate, confidence interval, or primary-endpoint significance test is available in the posted information.
This means the study question can be described, but its primary result cannot be interpreted quantitatively from this record. The direction of any difference, its magnitude, and its statistical precision are not reported. The absence of a numerical result is not evidence that the groups were identical, nor does it show that a difference was present. It leaves the comparison undetermined from the information recorded.
The record lists several secondary outcomes, including appropriate ICD shocks for ventricular arrhythmia, inappropriate ICD therapy, all ICD therapies, VT burden, mortality, cardiovascular hospitalizations, ICD storm, and incessant VT. These outcome names indicate the range of events considered, but outcome-specific numerical findings and analyses are not reported in the registry record. A list of outcomes is not itself evidence of a result.
Safety information is available in the adverse-event entries. For the renal sympathetic denervation group, the record lists 3 participants affected by serious adverse events among 9 at risk, and 5 affected by other adverse events among 9 at risk. For the VT ablation alone group, it lists 2 affected by serious adverse events among 8 at risk, and 3 affected by other adverse events among 8 at risk. Deaths are listed as 0 in each group. These are descriptive registry counts. The record does not supply an inferential comparison, uncertainty estimates, or enough detail to determine whether every event was judged related to the assigned treatment.
Because this is a randomized study, a well-conducted analysis could in principle estimate a comparative effect while accounting for uncertainty. But randomization alone does not provide the missing estimates, demonstrate that the assigned groups were analyzed as randomized, or resolve missing follow-up. The record does not report the analysis population or methods used for the primary outcome. The enrollment figure and completion status do not substitute for outcome data. No treatment conclusion should be drawn from the absence of reported primary results.
9. Statistical Methods Explained
The registry identifies the allocation as randomized, the masking classification as single, and the study model as parallel. It does not report a detailed statistical analysis plan. The explanations below are general statistical context, not claims about procedures used in this trial unless those procedures are explicitly described in the registry record.
How does randomization support a comparison?
In general, random assignment helps create groups whose baseline characteristics are comparable on average, including characteristics that were not measured. This supports interpreting a between-group contrast as an estimate of the effect of assignment, provided the trial is implemented and analyzed appropriately. Randomization does not guarantee that groups will be identical, especially in a small study, and it does not remove the need to report the assignment process, participant flow, outcome data, and analysis methods. The record does not describe the sequence-generation or allocation-concealment procedures.
What does a first-event endpoint capture?
Freedom from a first event is a time-to-event type of outcome: it concerns whether and when a participant first has an event meeting the definition. A probability at a stated follow-up time describes the chance of having remained event-free through that point under the chosen analysis. This differs from a count endpoint, which may include repeated events. Here, the registry specifies freedom from a first event requiring ICD therapy and names 12 months and 24 months, but it does not report the method used to estimate the probabilities.
General time-to-event analyses can use information from participants who have not experienced the event by the time their observation ends. Such observations are often treated as censored, meaning the event time is not known beyond the last observed follow-up. This approach depends on assumptions about why follow-up ended and on accurate follow-up and event ascertainment. The registry does not report censoring rules, follow-up completeness, or the handling of participants whose event status was unknown.
How should uncertainty be understood?
In general, a confidence interval expresses uncertainty around an estimated quantity under the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, while an interval spanning a range of plausible effects may leave substantial uncertainty about the size or direction of a contrast. A p-value, when reported, addresses compatibility of the observed data with a specified null hypothesis under a statistical model; it does not measure clinical importance or the probability that a hypothesis is true. Neither confidence intervals nor p-values for the primary endpoint are reported in the registry record.
The number enrolled does not, on its own, reveal the precision of an endpoint estimate. Precision also depends on the number and timing of events, completeness of follow-up, and the analysis method. The primary endpoint values and corresponding event information are not reported, so precision cannot be assessed from the posted information.
What do the count outcomes require?
Several registered outcomes concern counts, such as the number of ICD shocks or episodes of VT burden. General count-data methods consider both the average event frequency and the variability around that average. When the observed variability is greater than a simple count model expects, over-dispersion can make conventional standard errors too small if it is ignored. Methods that allow extra variability may then be appropriate. The registry record does not report the statistical models, dispersion assumptions, or numerical analyses for these count outcomes; no particular method should be attributed to the trial.
Counts also need a clearly stated observation period and denominator. A participant observed for longer may have more opportunity to experience events. For repeated events, an analysis may need to account for within-participant dependence, because episodes from the same person are not necessarily independent. The registry’s outcome list does not give sufficient detail to determine how observation time or repeated events were handled.
What can planning illustrations tell readers?
In general, sample-size calculations are planning exercises based on assumptions about an effect, variability, significance level, allocation, and analysis method. They describe the scale of a future study under those assumptions; they are not observed results and do not establish the probability that this completed trial detected an effect. The record describes planning illustrations based on a fraction of an observed effect and specifies a two-sided significance level of 0.05, equal allocation, and a normal approximation. It also distinguishes total event counts for time-to-event illustrations from participants per arm for other illustrations. Numerical planning estimates are not reported in the registry information used for this analysis, and the illustrations should not be mistaken for trial outcomes.
The registry does not report the trial’s own sample-size justification, a statistical analysis plan, interim analyses, or the prespecified approach to multiplicity. Those details cannot be reconstructed from the endpoint names or the design classification.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint at 12 months and 24 months, along with multiple secondary outcomes covering ICD therapies, VT burden, mortality, ICD storm, and cardiovascular hospitalization. When a study examines several outcomes or time points, the chance of at least one apparently unusual finding can increase if each is tested separately without an appropriate plan. General approaches include identifying a primary comparison in advance, adjusting inference across selected tests, or treating secondary analyses as exploratory. The method used for this trial is not reported in the registry record.
The record does not provide numerical outcome results or analysis entries for the primary endpoint. It therefore does not show whether both time points were analyzed, how a primary comparison was defined, or whether any multiplicity adjustment was used. The listed outcomes should not be read as evidence that each had a completed or interpretable analysis.
Missing data and follow-up are also important for a first-event endpoint. A participant without a recorded event may have remained event-free, may have had incomplete observation, or may have had an event that was not captured. General analysis methods distinguish these situations and require assumptions about censoring and missingness. The registry record does not report missing-outcome counts, follow-up completeness, reasons for loss to follow-up, censoring rules, or sensitivity analyses. It also does not specify an intention-to-treat, per-protocol, or other analysis population. Consequently, the extent to which the reported adverse-event groups or any intended efficacy analysis correspond to all randomized participants cannot be determined from the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Renal Sympathetic Denervation | 3 | 9 | 33.3% |
| VT Ablation Alone | 2 | 8 | 25.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Renal Sympathetic Denervation | 0 of 9 |
| VT Ablation Alone | 0 of 8 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Renal Sympathetic Denervation | 5 of 9 |
| VT Ablation Alone | 3 of 8 |
Most frequent serious adverse event terms
| Event term | Organ system | Renal Sympathetic Denervation | VT Ablation Alone |
|---|---|---|---|
| VT recurrence | Cardiac disorders | 0 of 9 | 2 of 8 |
| Non-sustained VT | Cardiac disorders | 0 of 9 | 1 of 8 |
| Pneumonia | Infections and infestations | 0 of 9 | 1 of 8 |
| Macrohematuria | Renal and urinary disorders | 0 of 9 | 1 of 8 |
| AF with urosepsis | General disorders | 1 of 9 | 0 of 8 |
| Worsening heart failure/Total artifical heart implant | Cardiac disorders | 1 of 9 | 0 of 8 |
| Pseudoaneurysm at septal aspect of LV apex | Cardiac disorders | 1 of 9 | 0 of 8 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Renal Sympathetic Denervation | VT Ablation Alone |
|---|---|---|---|
| VT recurrence | Cardiac disorders | 0 of 9 | 2 of 8 |
| Dissection of left external iliac artery | Cardiac disorders | 0 of 9 | 1 of 8 |
| Paresthesia | Skin and subcutaneous tissue disorders | 0 of 9 | 1 of 8 |
| LUE Cephalic vein thrombosis | Vascular disorders | 1 of 9 | 0 of 8 |
| Hypotension with pleuritic chest pain | Cardiac disorders | 1 of 9 | 0 of 8 |
| Kidney pain with near syncope | Hepatobiliary disorders | 1 of 9 | 0 of 8 |
| Flu | Infections and infestations | 1 of 9 | 0 of 8 |
| Bradycardia associated with dyspnea on exertion | Cardiac disorders | 1 of 9 | 0 of 8 |
| Jaw pain | Musculoskeletal and connective tissue disorders | 1 of 9 | 0 of 8 |
Serious events with the highest arm-level rate: vt recurrence (25.0%), non-sustained vt (12.5%), pneumonia (12.5%), macrohematuria (12.5%), af with urosepsis (11.1%).
The adverse-event entries list serious and other adverse events separately. In the renal sympathetic denervation group, 3 participants were affected by serious adverse events among 9 at risk, and 5 were affected by other adverse events among 9 at risk. In the VT ablation alone group, 2 participants were affected by serious adverse events among 8 at risk, and 3 were affected by other adverse events among 8 at risk. The registry lists deaths as 0 in each group.
These figures are descriptive counts, not a formal comparison of safety between randomized groups. The record does not provide confidence intervals or a statistical test for these counts. It also does not report the detailed event definitions, the relationship of each event to treatment, or whether participants could contribute to more than one event category. The serious adverse-event terms listed include VT recurrence, non-sustained VT, pneumonia, macrohematuria, AF with urosepsis, and worsening heart failure/Total artifical heart implant, with percentages recorded in the registry. Those terms and percentages should be read as registry listings, not as proof that a particular treatment caused an event. A count of affected participants does not by itself describe event severity, duration, timing, or the completeness of ascertainment.
12. What the Result Does, and Does Not, Mean
The registry record defines a clinically relevant comparison: renal sympathetic denervation added to VT ablation versus VT ablation alone, with freedom from a first event requiring ICD therapy as the primary endpoint. It records a randomized, single-masked, parallel design and a completed status. These details establish what the study set out to compare; they do not establish the result of that comparison.
Numerical primary-endpoint probabilities and a comparative estimate are not reported in the registry record. Accordingly, the posted information does not show whether one group had a higher or lower probability of remaining free from the first qualifying event, nor does it show how precisely a difference was estimated. The same caution applies to the listed secondary outcomes: their names do not establish their findings. No conclusion about benefit or lack of benefit follows from the absence of numerical efficacy results in this record.
The adverse-event entries do offer descriptive group counts, including the serious-event and other-event figures and the deaths listed as 0 in each group. These entries can describe what the registry records, but without uncertainty estimates, detailed definitions, treatment attribution, and fuller follow-up information, they do not by themselves establish comparative safety. An observed count is not a causal conclusion.
General statistical interpretation distinguishes a point estimate from its uncertainty and from clinical importance. A result can be imprecise even when a numerical estimate exists, and a statistical test alone would not determine whether a difference matters clinically. In this case, the primary estimates and inferential results are not reported, so neither precision nor clinical magnitude can be evaluated from the posted information. The appropriate reading is that the registry documents the trial question, design, endpoint, and some safety counts, while the principal efficacy comparison remains unreported.
13. Why This Trial Matters Statistically
This trial is statistically notable for asking an adjunctive-treatment question in a randomized parallel design. The comparison keeps VT ablation as the shared procedure and contrasts adding renal sympathetic denervation with receiving no further therapy in addition to VT ablation. That structure targets the incremental contrast relevant to the registered question, rather than comparing ablation with no ablation.
The primary endpoint is framed as freedom from a first event requiring ICD therapy, with stated follow-up assessments at 12 months and 24 months. This makes both event timing and follow-up important to interpretation. A registry entry that names time points without reporting the corresponding probabilities, event information, and uncertainty cannot support a quantitative estimate of the treatment contrast. The absence of those results is a central statistical limitation, not a finding that the groups were similar.
The record also registers a range of secondary clinical outcomes, including recurrent arrhythmia-related events, ICD therapies, mortality, and hospitalization. Such breadth can be useful for describing the questions considered, but it makes prespecification and multiplicity handling important. Those analysis details are not reported in the registry record, and the outcome list alone cannot establish which analyses were completed or how they should be interpreted.
The safety entries illustrate why counts need context. They give affected-participant counts and at-risk counts for each group, but do not include comparative uncertainty or detailed attribution. With outcome results absent for the primary question, readers should distinguish the existence of a randomized trial record from the availability of an interpretable treatment-effect estimate. The record matters as documentation of a prospective randomized question, while the posted information does not resolve that question statistically.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The principal trial-specific limitation in the registry information is that numerical results for the primary endpoint are not reported. The record describes freedom from a first event requiring ICD therapy at 12 months and 24 months, but does not give the probabilities, a between-group contrast, confidence intervals, or a test result. This prevents assessment of effect direction, magnitude, and precision.
The outcome description does not specify the operational definition of an event requiring ICD therapy, event-adjudication procedures, or how recurrent events were handled for the primary endpoint. The record also does not state the method used to estimate freedom from an event, the censoring rules, or how incomplete follow-up was treated. These omissions matter because endpoint definitions and follow-up methods shape the estimate.
Although the design is classified as randomized and single-masked, the record does not describe the randomization procedure, concealment, or who was masked. The analysis population and participant flow are also not reported. No statistical analysis plan, sample-size justification for the trial, interim-analysis details, or multiplicity approach is reported in the registry record.
Safety information is limited to registry counts and listed serious-event terms. The record does not provide detailed event timing, treatment attribution, uncertainty estimates, or enough information to determine how overlapping events were counted. The listed secondary outcomes do not include numerical findings in the posted information. These limitations concern what can be interpreted from the registry record and should not be mistaken for proof that the trial did not collect the information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: REnal Sympathetic dEnervaTion as an a Adjunct to Catheter-based VT Ablation — NCT01858194.
- Registry record last updated 2020-04-17; status last verified 2020-04.
- Results first posted 2020-04-17.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT01858194 is recorded as a completed, randomized, single-masked, parallel study with enrollment of 21. It compares catheter-based renal sympathetic denervation added to VT ablation with VT ablation alone. The registered condition is ventricular tachycardia, and the study description concerns patients with ischemic or non-ischemic ventricular dysfunction who were to receive catheter-based VT ablation.
The primary endpoint is freedom from a first event requiring ICD therapy, described at 12 months and 24 months. Numerical primary-outcome results and comparative statistical analyses are not reported in the registry record. The record lists secondary outcomes and provides descriptive adverse-event counts, including deaths listed as 0 in each group. It does not report the analysis population, missing-data approach, or detailed statistical plan. The trial question and design are documented, but the primary efficacy comparison cannot be assessed from the posted results.