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 Accent Cardiac MRI Study (NCT02041702), a randomized na study. The primary outcome is Change in Right Atrial (RA) Capture Threshold @0.5 Millisecond (ms) From Pre-MRI Scan to 1 Month After MRI Scan.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02041702 |
| Phase | NA |
| Condition | Bradycardia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 283 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Abbott Medical Devices |
| Results posted | Yes |
2. Clinical Question
Population
Participants with bradycardia and an implanted SJM MRI-conditional pacing system were the population of interest. The primary endpoint population was narrower: it included participants who were successfully implanted, randomized, completed the MRI and one-month post-MRI visit, and met stated sensing-amplitude and intrinsic-rate criteria. The registry’s description of this population ends with an incomplete phrase about receiving an MRI scan, so the full eligibility wording is not reported in the registry record.
Intervention
The intervention was a non-diagnostic cardiac MRI scan. The study aim was to assess safety and efficacy of the pacing system in this setting and to examine whether the scan affected system performance.
Comparator
The comparator was the control group. The registry does not give a fuller description of the control group or explain its assigned procedures, so those details are not reported in the registry record.
Primary question
The primary question concerned the number of participants whose right atrial capture threshold at 0.5 ms had an increase of no more than 0.5 V at one month after MRI, relative to the pre-MRI value. The registry also reports a sponsor analysis framed as a non-inferiority comparison between the cardiac MRI scan and control groups.
3. Trial Design
The Accent Cardiac MRI Study was a randomized, open-label, parallel-group clinical study. It enrolled 283 participants and is recorded as completed. The registry identifies Abbott Medical Devices as the sponsor and lists bradycardia as the condition. The study’s stated aim was to assess safety and efficacy of the SJM MRI-conditional pacing system and to test the hypothesis that a cardiac MRI scan would not affect its performance.
Participants were assigned to a Cardiac MRI Scan Group or a Control Group. Masking was none, so the trial was not described as blinded. The registry lists a non-diagnostic cardiac MRI scan as the intervention, but the control group’s procedures and the allocation ratio are not described. The methods of random sequence generation, allocation concealment, and any stratification are not reported in the registry record.
The primary outcome concerns change from the MRI-visit pre-scan value to the value at one month after the MRI visit. The posted endpoint counts are 110 of 111 participants in the Cardiac MRI Scan Group and 117 of 117 in the Control Group. These endpoint denominators are not the same as total enrollment; the registry’s primary-population description sets additional completion and measurement criteria. A detailed accounting of participant flow, exclusions, or missing endpoint values is not reported in the registry record.
The registry lists five outcome measures and five analyses, while no secondary results are posted. It does not provide the full statistical analysis plan or clarify whether the reported primary analysis was prespecified in the same form as the sponsor’s posted non-inferiority analysis.
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 | Cardiac MRI Scan Group | Control Group |
|---|---|---|
| STARTED | 140 | 143 |
| Pre MRI Scan/ Pre Waitng | 129 | 140 |
| Post MRI Scan/ Post Waiting | 129 | 140 |
| COMPLETED | 129 | 134 |
| NOT COMPLETED | 11 | 9 |
Reasons for not completing this period:
| Reason | Cardiac MRI Scan Group | Control Group |
|---|---|---|
| Lost to Follow-up | 1 | 6 |
| Death | 4 | 0 |
| Withdrawal by Subject | 4 | 3 |
| Patient not confirmed as MRI compatible | 1 | 0 |
| Cardiac Resynchronization Therapy | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: All subjects in Cardiac MRI Scan group who underwent an elective non-diagnostic cardiac MRI scan and completed all protocol specific visits were included in the analysis. Subjects who withdrew from the study before 1 month post MRI visit and had no MRI scan related complications were excluded.
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 | Cardiac MRI Scan Group | Control Group | Total |
|---|---|---|---|---|
| Participants analysed | 140 | 143 | 283 | |
| Age, Continuous | years | 71.4 (SD 11.2) | 67.4 (SD 11.7) | 69.4 (SD 11.6) |
| Sex: Female, Male: Female | Participants | 58 | 61 | 119 |
| Sex: Female, Male: Male | Participants | 82 | 82 | 164 |
| Region of Enrollment: Hong Kong | Participants | 15 | 15 | 30 |
| Region of Enrollment: China | Participants | 3 | 4 | 7 |
| Region of Enrollment: Malaysia | Participants | 2 | 3 | 5 |
| Region of Enrollment: Thailand | Participants | 46 | 46 | 92 |
| Region of Enrollment: India | Participants | 54 | 55 | 109 |
| Region of Enrollment: Singapore | Participants | 20 | 20 | 40 |
| Cardiomyopathy History: Ischemic Cardiomyopathy | Participants | 2 | 3 | 5 |
| Cardiomyopathy History: Non-ischemic Cardiomyopathy | Participants | 1 | 0 | 1 |
| Arrhythmia History: Atrial Fibrillation | Participants | 29 | 26 | 55 |
| Arrhythmia History: Atrial Flutter | Participants | 7 | 6 | 13 |
| Arrhythmia History: Premature Ventricular | Participants | 1 | 2 | 3 |
| Arrhythmia History: Monomorphic Ventricular Tachycardia | Participants | 1 | 0 | 1 |
| Arrhythmia History: Supraventricular Tachycardia | Participants | 1 | 0 | 1 |
| Cardiovascular Medication: Angiotensin Converting Enzyme Inhibitor | Participants | 18 | 17 | 35 |
| Cardiovascular Medication: Angiotensin II Receptor Blockers | Participants | 31 | 31 | 62 |
| Cardiovascular Medication: Beta-Blockers | Participants | 31 | 19 | 50 |
| Cardiovascular Medication: Aldosterone Inhibitors | Participants | 0 | 2 | 2 |
| Cardiovascular Medication: Antiarrhythmics (Class I) | Participants | 3 | 1 | 4 |
| Cardiovascular Medication: Antiarrhythmics (Class II) | Participants | 2 | 7 | 9 |
| Cardiovascular Medication: Anticoagulants | Participants | 15 | 13 | 28 |
| Cardiovascular Medication: Antiplatelets | Participants | 47 | 48 | 95 |
| Cardiovascular Medication: Calcium Channel Blockers | Participants | 54 | 40 | 94 |
| Cardiovascular Medication: Cardiac Glycosides (Digitalis) | Participants | 2 | 1 | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Right Atrial (RA) Capture Threshold @0.5 Millisecond (ms) From Pre-MRI Scan to 1 Month After MRI Scan, measured over MRI Visit ,1 Month Post MRI Visit.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants who experienced an increase in right atrial (RA) capture threshold at 0.5 ms of no more than 0.5 V at the one-month post-MRI visit, compared with the pre-MRI value measured at the MRI visit. A capture threshold is the stimulation level needed to produce a cardiac response. Tracking a change in that threshold is relevant to assessing whether pacing-system performance was altered over the period being studied.
This is a binary endpoint: each participant is counted according to whether the defined event occurred. It is not a measurement of the average threshold change, and the posted values do not reveal how far individual participants’ measurements changed. The criterion combines a direction of change with a specified limit, so the count describes participants meeting that stated definition rather than every possible change in device performance.
The endpoint population is restricted to participants who were successfully implanted, randomized, completed the MRI and one-month visit, and met specified sensing and intrinsic-rate criteria. The registry’s population description is incomplete at its end, which limits a full understanding of the exact analysis population. The outcome is therefore best interpreted as a count within the posted eligible group, rather than as an outcome measured in every enrolled participant.
7. Results Posted in the Registry
- Cardiac MRI Scan Group: 99.1% (110/111) versus 100.0% (117/117) on control; risk difference -0.9 percentage points (95% CI -2.7 to 0.9), risk ratio 0.99 (0.97–1.01); unadjusted two-proportion z-test p = 0.304.
Risk difference: Cardiac MRI Scan Group
95% CI: -2.7 to 0.9 percentage points
Recalculated from the posted summary statistics
8. Statistical Interpretation
For the primary endpoint, 110 of 111 participants in the Cardiac MRI Scan Group and 117 of 117 in the Control Group were counted as having the defined threshold outcome. The posted unadjusted recalculation gives a risk difference of -0.009, with a 95% confidence interval from -0.027 to 0.009 and an unadjusted p-value of 0.304. The estimate is close to zero, and the interval includes zero. This recalculation does not, by itself, establish equivalence or non-inferiority; those conclusions depend on a prespecified margin and an analysis appropriate to that design.
The registry separately posts a sponsor analysis using a Farrington-Manning Test, with the result described as a ratio difference of -0.9 and a 90% confidence interval from -5.6 to 3.8. It reports p < 0.001 for a non-inferiority analysis. Because the registry marks a discrepancy between the sponsor-reported result and the simple recalculation, the sponsor’s own analysis takes precedence for interpretation of the sponsor’s stated non-inferiority claim. The two analyses should not be merged or treated as interchangeable: they differ in reported metric, confidence level, and inferential approach.
The registry does not report the non-inferiority margin, the analysis specification, or the assumptions supporting the sponsor’s test. Without those details, a reader cannot independently assess the prespecified decision rule or determine how the sponsor’s result relates to its chosen margin. The reported p-value is not a general test that the groups are identical; it belongs to the sponsor’s non-inferiority analysis.
The counts are also subject to the endpoint population definition. The primary analysis includes participants meeting stated completion and measurement criteria, rather than necessarily every randomized participant. The registry does not report a complete participant flow or detailed handling of missing data. The results therefore describe the posted endpoint groups and should not be extended to unreported participants or outcomes.
These results concern a defined device-performance endpoint at a particular follow-up visit. They do not, on their own, answer every question about MRI safety, all pacing-system functions, long-term performance, or clinical outcomes. The registry’s serious adverse event figures are a separate descriptive safety record and should be considered on their own terms.
9. Statistical Methods Explained
The main endpoint is binary, meaning that each participant contributes to one of two categories: meeting or not meeting the registry’s definition of the threshold outcome. For a binary outcome, a group’s event risk is the proportion of participants with the event among those included in that group’s analysis. A risk difference expresses the contrast between two such risks on an absolute scale. The posted recalculation reports a risk difference of -0.009 for the Cardiac MRI Scan Group relative to control. A negative value indicates a lower event proportion in the MRI group under the direction used for that comparison; it does not establish that the groups are clinically equivalent.
The recalculation is explicitly unadjusted and based on posted summary counts. An unadjusted comparison does not account for covariates or other potential adjustments. No adjusted estimate is reported in the registry record. The posted 95% confidence interval gives a range of values compatible with the recalculation under its statistical assumptions. Its inclusion of zero means that the data do not distinguish the estimated risk difference from zero at the conventional two-sided 0.05 level using this interval-based interpretation. That statement is about this recalculation, not about the sponsor’s separately reported non-inferiority test.
A conventional test of whether a difference is zero and a non-inferiority test answer different questions. A test of zero difference evaluates whether evidence is inconsistent with exactly equal event risks. A non-inferiority analysis instead asks whether the intervention is not worse than the comparator by more than a chosen margin. The margin is essential: it defines the largest difference that would still satisfy the study’s non-inferiority criterion. The margin and the sponsor’s full decision rule are not reported in the registry record, so the non-inferiority analysis cannot be independently reconstructed from the posted information.
Why do the reported analyses differ?
The registry posts a Farrington-Manning Test with a ratio difference of -0.9, a 90% confidence interval from -5.6 to 3.8, and p < 0.001 for non-inferiority. The recalculation instead gives an unadjusted risk difference and a 95% confidence interval. A Farrington-Manning approach is used for testing non-inferiority or equivalence with binary outcomes, where the hypotheses and variance calculation reflect the chosen margin. It is therefore not simply a second expression of the same zero-difference test. The registry identifies a discrepancy, and the sponsor’s own analysis takes precedence for the sponsor’s stated non-inferiority analysis.
The differing metrics and confidence levels matter. A confidence interval is interpreted relative to the quantity it estimates and the analysis that produced it. The sponsor’s interval should be judged against the non-inferiority margin, not against zero alone; because the margin is not reported in the registry record, that comparison cannot be completed independently. The recalculated interval describes an unadjusted absolute risk difference and includes zero, but that fact cannot settle the sponsor’s non-inferiority question.
What does the p-value say?
A p-value measures how compatible the observed data are with a specified null hypothesis under the assumptions of the test. It is not the probability that the null hypothesis is true, nor a measure of the size or clinical importance of an effect. The unadjusted p-value of 0.304 belongs to the recalculated comparison; p < 0.001 belongs to the sponsor’s reported non-inferiority test. Because their hypotheses and methods differ, the p-values should not be compared as though they were competing answers to the same question.
For planning illustrations, the registry describes a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect set as a stated fraction of the observed effect. Such illustrations are conditional on their assumptions and are not observed power. The posted sample-size assumptions do not establish what planning method the trial itself used. The trial’s original sample-size justification is not reported in the registry record.
In general, over-dispersion means that observed variability exceeds what a model assumes. It can make standard errors too small if ignored, leading to overly narrow intervals or optimistic tests. No over-dispersion analysis is described for this binary endpoint, and it should not be assumed to have been used or required. More broadly, randomization can support a fair group comparison, but interpretation still depends on allocation procedures, complete outcome ascertainment, analysis populations, and faithful implementation of the prespecified statistical plan. Those details are not fully reported in the registry record.
10. Confidence Intervals and Precision
The unadjusted recalculation estimates a risk difference of -0.009, with a 95% confidence interval from -0.027 to 0.009. The interval describes uncertainty in the estimated absolute difference under the recalculation’s assumptions. It spans values on both sides of zero, so the estimate is compatible with a small difference in either direction. The interval is more informative about precision than the point estimate alone, but it does not establish equivalence or non-inferiority.
Confidence intervals are not guarantees that the true value lies within the particular interval, nor do they show the probability that a treatment effect is in a range. They summarize the behavior of an estimation procedure across repeated samples under its assumptions. The practical interpretation also depends on what size of difference would matter and, for non-inferiority, on the prespecified margin. The registry does not report that margin, so the interval cannot be assessed against the sponsor’s decision threshold.
The sponsor’s reported non-inferiority analysis has a 90% confidence interval from -5.6 to 3.8 for the reported ratio difference of -0.9. This is a different inferential result from the 95% interval for the unadjusted risk difference. The interval widths and endpoints should not be compared directly without accounting for the difference in estimand, method, and confidence level. Its relation to the non-inferiority margin cannot be determined from the registry record.
Precision is also affected by the analysis population and endpoint ascertainment. The primary endpoint counts include 111 participants in the MRI group and 117 in control, while total enrollment was 283. The record does not provide a complete flow explaining the difference, detailed missing-data handling, or a sensitivity analysis. Those omissions limit assessment of how robust the estimated precision is to exclusions or unavailable measurements.
11. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Farrington-Manning Test | Ratio Difference -0.9 | -5.6 to 3.8 | < 0.001 |
The registry reports the sponsor’s analysis as a Farrington-Manning Test for non-inferiority. Its posted result is a ratio difference of -0.9, with a 90% confidence interval from -5.6 to 3.8 and p < 0.001. That analysis addresses whether the MRI group met the sponsor’s non-inferiority criterion, rather than simply whether an unadjusted difference was statistically distinguishable from zero.
A separate recalculation from the posted counts estimates an unadjusted risk difference of -0.009, with a 95% confidence interval from -0.027 to 0.009 and p = 0.304. The registry identifies a discrepancy between this recalculation and the sponsor’s analysis. Under that circumstance, the sponsor’s own analysis takes precedence for interpretation of the sponsor’s stated non-inferiority result; the recalculation is a simple, unadjusted check, not a replacement for the trial’s reported analysis.
The registry does not report the non-inferiority margin or enough statistical-plan detail to reproduce the sponsor’s result fully. Consequently, the reported p-value should be read as part of the sponsor’s non-inferiority analysis, without inferring the exact margin or treating it as evidence of equality. The two estimates answer different statistical questions and should remain clearly distinguished.
12. Multiplicity, Missing Data and Analysis Populations
The registry lists five outcome measures and five analyses, but no secondary results are posted. It does not describe a multiplicity adjustment, a hierarchy of endpoints, or a strategy for controlling the chance of false-positive findings across multiple outcomes. Those details are not reported in the registry record. The posted sponsor result relates to the stated primary endpoint, but the registry does not establish how that endpoint was prioritized relative to the other listed measures.
Multiplicity arises when several hypotheses are tested. If each is assessed separately without adjustment, the overall chance of at least one false-positive result can increase. Whether adjustment is appropriate depends on the study’s objectives and prespecified testing strategy. Since that strategy is not reported, no conclusion should be drawn about whether multiplicity was controlled or how it would affect interpretation.
The primary endpoint population description includes successful implantation, randomization, completion of MRI and the one-month visit, and specified measurement criteria. Its final phrase is incomplete in the registry record. Although endpoint denominators are posted for both groups, a full flow from enrollment through randomization, follow-up, and analysis is not reported. The record also does not explain whether participants were excluded for missing measurements, incomplete visits, protocol deviations, or other reasons.
Detailed missing-data methods are not reported in the registry record. There is no posted description of imputation, assumptions about missingness, or sensitivity analyses. The available counts therefore cannot establish whether missing outcomes could have affected the comparison. The registry also does not specify an intention-to-treat analysis, a per-protocol analysis, or how the sponsor defined its analysis population for non-inferiority. These omissions matter because the handling of participants who do not complete follow-up can influence the interpretation of a non-inferiority result.
Interim analyses, stopping rules, and the full statistical analysis plan are not reported in the registry record. Their absence from the record should not be taken as evidence that such procedures were or were not used. The registry provides the posted results, but not all the design and analysis detail needed to assess the complete inferential framework.
13. 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 |
|---|---|---|---|
| Cardiac MRI Scan Group | 6 | 140 | 4.3% |
| Control Group | 6 | 143 | 4.2% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cardiac MRI Scan Group | 4 of 140 |
| Control Group | 0 of 143 |
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 |
|---|---|
| Cardiac MRI Scan Group | 1 of 140 |
| Control Group | 1 of 143 |
Most frequent serious adverse event terms
| Event term | Organ system | Cardiac MRI Scan Group | Control Group |
|---|---|---|---|
| Righ Atrial Lead Dislodgement | Cardiac disorders | 0 of 140 | 2 of 143 |
| Acute Non-St Elevation Myocardial Infarction | Cardiac disorders | 0 of 140 | 1 of 143 |
| Anaphylaxis, Anaphylactoid | General disorders | 1 of 140 | 0 of 143 |
| Cardiac Tamponade | Injury, poisoning and procedural complications | 0 of 140 | 1 of 143 |
| Dressler's Syndrome | Cardiac disorders | 0 of 140 | 1 of 143 |
| Drug Allergy | General disorders | 1 of 140 | 0 of 143 |
| Intracranial Hemorrhage | Vascular disorders | 1 of 140 | 0 of 143 |
| Pericardial Effusion | Injury, poisoning and procedural complications | 1 of 140 | 0 of 143 |
| Right Ventricular Lead Dislodgement | Cardiac disorders | 1 of 140 | 0 of 143 |
| System Infection | Infections and infestations | 0 of 140 | 1 of 143 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cardiac MRI Scan Group | Control Group |
|---|---|---|---|
| New Onset Paroxysmal Atrial Fibrillation | Cardiac disorders | 0 of 140 | 1 of 143 |
| Retracted Right Atrial Lead | General disorders | 1 of 140 | 0 of 143 |
Serious events with the highest arm-level rate: righ atrial lead dislodgement (1.4%), anaphylaxis, anaphylactoid (0.7%), drug allergy (0.7%), intracranial hemorrhage (0.7%), pericardial effusion (0.7%).
The registry reports serious adverse events for 6 participants among 140 at risk in the Cardiac MRI Scan Group and 6 among 143 at risk in the Control Group. It reports other adverse events for 1 participant in each group, with the same at-risk group sizes. Four deaths are listed for the MRI group and zero for control. These are descriptive counts in the registry; they do not, by themselves, establish that an event was caused by the scan or the pacing system.
The serious-event terms listed include Righ Atrial Lead Dislodgement at 1.4%, and Anaphylaxis, Anaphylactoid; Drug Allergy; Intracranial Hemorrhage; Pericardial Effusion; and Right Ventricular Lead Dislodgement, each at 0.7%. These terms should be understood as registry-coded event descriptions. The record does not provide enough detail to determine event timing, severity beyond the serious-event classification, relatedness assessments, recurrence, or the clinical circumstances for each event.
The safety denominators differ from the posted primary endpoint denominators. The registry does not explain the difference in analysis populations or give a participant-level account linking events to the intervention. The event counts are not a substitute for a comparative safety analysis, and no additional risk calculation is made from them. They provide a limited description of events recorded during the study, not a complete account of safety.
14. What the Result Does, and Does Not, Mean
The posted primary endpoint results describe the number of participants meeting a narrowly defined right atrial capture-threshold criterion at one month after MRI. They show 110 of 111 in the Cardiac MRI Scan Group and 117 of 117 in the Control Group. The unadjusted recalculation is close to zero and its 95% confidence interval includes zero. Separately, the sponsor reports a non-inferiority test with p < 0.001. These findings belong to different analyses and should not be collapsed into a single claim.
The sponsor’s result is the relevant posted analysis for its non-inferiority conclusion, and the registry flags a discrepancy with the recalculation. The non-inferiority margin is not reported in the registry record, so readers cannot independently compare the sponsor’s estimate and interval with the decision threshold. The recalculation can describe an unadjusted risk difference, but it cannot substitute for the sponsor’s margin-based test.
The endpoint is a surrogate measure of device performance at a specific follow-up point. It is not a comprehensive measure of all system functions, all possible effects of MRI, long-term performance, or clinical outcomes. The primary analysis population is restricted by completion and measurement criteria, and the registry does not provide a full participant flow or detailed missing-data methods. As a result, the posted counts should not be generalized automatically to every enrolled participant.
The study was randomized, but the registry does not describe the sequence-generation or concealment procedures, and masking was none. The control procedures are not fully described. These gaps limit assessment of the trial’s implementation and the context for the comparison. The adverse-event counts offer additional descriptive information but do not establish causation or provide a complete safety profile.
Overall, the record supports a careful account of the posted endpoint counts and the sponsor’s reported non-inferiority analysis. It does not support claims beyond those outcomes and analyses, nor does it resolve unreported methodological details.
15. Why This Trial Matters Statistically
This trial illustrates why the statistical question must be identified before interpreting a result. A test of zero difference, an estimate of an unadjusted risk difference, and a non-inferiority test do not ask the same question. The primary endpoint counts can be used to describe a simple unadjusted contrast, while the sponsor’s Farrington-Manning analysis addresses a margin-based non-inferiority claim. The registry’s discrepancy flag makes that distinction especially important.
It also shows why a p-value cannot be read without its hypothesis and method. The unadjusted p-value of 0.304 and the sponsor-reported p < 0.001 are attached to different analyses. Neither should be interpreted as a general probability that the groups are the same or different. In non-inferiority work, the margin is central to meaning, yet it is not reported in the registry record. A statistically reported result may therefore be difficult for a reader to independently audit.
The case also demonstrates the importance of transparent analysis populations. Total enrollment is 283, while the posted endpoint counts use narrower group denominators and require completion and measurement criteria. Without full participant flow and missing-data methods, it is hard to assess the possible influence of exclusions or incomplete follow-up. Randomization is important, but interpreting results also requires knowing how randomized participants were carried through analysis.
Finally, the registry separates device-performance outcomes from adverse-event reporting. Counts of threshold outcomes and serious events answer different questions and should not be combined into a single summary of safety or efficacy. Clear definitions, denominators, analysis methods, and uncertainty intervals help keep those interpretations appropriately bounded.
16. 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 trial-specific details needed for a full statistical assessment are not reported in the registry record. These include the non-inferiority margin, a complete analysis plan, the original sample-size justification, and the rationale for the sponsor’s chosen inferential method. The sponsor’s test is reported, but the information needed to reproduce it or compare its interval with the decision threshold is not available.
The endpoint population description is restrictive and ends with an incomplete phrase. Although it specifies successful implantation, randomization, completion of the MRI and one-month visit, and measurement criteria, the last eligibility detail cannot be fully understood. The registry gives endpoint denominators but not a complete accounting of participant flow or reasons for exclusion. Detailed missing-data handling and sensitivity analyses are also not reported.
The control group is not described beyond its label, and the registry does not give details of random sequence generation, allocation concealment, or stratification. Masking is listed as none. The intervention is identified as a non-diagnostic cardiac MRI scan, but the record does not give a fuller description of the control procedures or the MRI protocol.
Only the primary endpoint result is described in detail; no secondary results are posted despite five outcome measures and five analyses being listed. Multiplicity procedures and the role of any additional outcomes are not reported. The serious adverse-event figures are descriptive and lack participant-level timing, relatedness, and clinical context. These limitations do not negate the posted results, but they constrain how broadly or confidently they can be interpreted.
17. Related Tutorials
18. Related Statistical Calculators
19. Sources
- ClinicalTrials.gov: Accent Cardiac MRI Study — NCT02041702.
- Registry record last updated 2019-08-21; status last verified 2019-08.
- Results first posted 2019-08-21.
- 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.
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20. Record Summary
The Accent Cardiac MRI Study was a completed randomized, open-label, parallel-group study sponsored by Abbott Medical Devices. It enrolled 283 participants with bradycardia and compared a Cardiac MRI Scan Group with a Control Group. Its stated aim was to assess safety and efficacy of an SJM MRI-conditional pacing system and examine whether cardiac MRI affected system performance.
The primary endpoint counted participants meeting a right atrial capture-threshold criterion from the pre-MRI measurement to one month after MRI. The posted counts were 110 of 111 in the MRI group and 117 of 117 in control. The registry reports a sponsor-led Farrington-Manning non-inferiority analysis and flags a discrepancy with an unadjusted recalculation from the counts. The sponsor’s analysis takes precedence for its stated non-inferiority claim, but the margin and fuller analysis details are not reported in the registry record.
The registry also reports serious and other adverse-event counts and deaths. Full participant flow, detailed missing-data procedures, secondary results, and several elements of the statistical plan are not reported.