Pediatric patients with left ventricular noncompaction (LVNC) and severe ventricular dysfunction are at risk for sudden death. The aims of this study were to (1) evaluate outcomes, (2) describe arrhythmic burden on Holter monitoring, and (3) analyze the utility of Holter monitoring and its impact on care in pediatric patients with LVNC and preserved or mild ventricular dysfunction. This was a retrospective study including patients <21 years of age with LVNC and ejection fractions ≥45%. Demographic and outcome data were analyzed. Individual and cumulative Holter data were evaluated for all patients. Arrhythmias, conduction system disease, and symptoms were analyzed for each Holter recording. The incidence of significant findings and the impact on care were determined for each study. Outcome and Holter data were compared between patients on the basis of the ejection fraction (≥55% [normal] or ≥45% to <55% [mild]). This study included 72 patients, 65 with normal function and 7 with mild dysfunction (mean age 13 years). There was a single death in the cohort, which was sudden in nature. Simple ventricular ectopy was common on Holter monitoring and more common in patients with mild dysfunction (86% vs 27%, p = 0.005). Significant Holter findings (4% vs 6%) and changes to patient care (2% vs 4%) improved with cumulative Holter monitoring. In conclusion, in contrast to patients with severe dysfunction, pediatric patients with LVNC and normal or mild dysfunction have significantly better outcomes. However, worsening LV systolic function was correlated with increasing ventricular ectopy. The role of Holter monitoring is unknown, but it may have utility in patient care if used as part of ongoing screening.
Left ventricular (LV) noncompaction (LVNC) is a form of cardiomyopathy characterized by hypertrabeculated myocardium. LVNC can present with several different associated phenotypes, including dilatated, hypertrophic, and restrictive cardiomyopathies, and can be seen in association with differing forms of congenital heart disease. Additionally, LVNC can be seen as an “isolated” finding associated with normal or near normal LV systolic function and chamber dimensions. Recent data have shown that specific cohorts of pediatric patients with LVNC have poor outcomes and that LVNC is associated with a propensity for sudden cardiac death. These studies have identified high-risk cohorts to be those with significant ventricular dysfunction and/or ventricular dilatation and a phenotype of LVNC with dilatated cardiomyopathy. In this subcohort, there was noted to be a high arrhythmic burden, proposed to be 1 of the mechanisms associated with poor outcomes. Initial data appear to suggest that patients with minimal ventricular dysfunction and normal chamber dimensions are at a significantly lower risk, although the arrhythmic burden and association with potential sudden cardiac death have not been specifically addressed. In this study, we sought to evaluate the outcomes and arrhythmic burden of pediatric patients with LVNC and relatively well preserved LV function (LV ejection fraction [LVEF] >45%) and to determine the utility of Holter monitoring in this population. The aims of this study were to (1) determine the outcomes of patients with LVNC, including death and sudden cardiac death; (2) describe the arrhythmia burden on Holter monitoring; and (3) determine the utility of Holter monitoring with regard to the detection of significant arrhythmia findings and the resultant changes in patient management. The population was further analyzed on the basis of the LVEF to determine if there are differences between patients with normal ventricular function and those with mild ventricular dysfunction (LVEF 45% to 54% vs >55%).
Methods
This was a single-center, retrospective analysis of pediatric patients with LVNC and associated well-preserved ventricular function and normal chamber dimensions. This study was approved by the Institutional Review Board at Cincinnati Children’s Hospital Medical Center (2014-3496). Patients were included in the analysis if they were followed in the cardiomyopathy-specific clinic with diagnoses of LVNC and were <22 years of age. Patients with LVEFs <45% were excluded from the analysis. Patients were initially identified from a Holter database and screened for the aforementioned criteria. The diagnosis of LVNC was made using noninvasive imaging methods. Echocardiography is typically the diagnostic approach used. However, cardiac magnetic resonance imaging is also used to establish the diagnosis in borderline cases or in patients with poor acoustic windows. The diagnosis is based on published criteria assessing ratios of noncompacted to compacted myocardium.
Patient demographics and echocardiographic and electrophysiologic data were obtained from hospital and cardiac-specific databases. Patient data, including age, gender, and race, as well as patient characteristics, including history of syncope, history of clinical arrhythmias, pacemaker or defibrillator implantation, genetic status, current use of antiarrhythmic medications, and the most recent ejection fraction, were reviewed. Patients were categorized into 2 groups according to LVEF: those with mild LV systolic dysfunction (LVEF ≥45% to <55%) and those with normal LV function (LVEF ≥55%). Outcome data, including death, aborted sudden cardiac death, and transplantation, were analyzed.
All Holter monitoring studies from January 2010 to the time of the study were reviewed. Patient age at the time of each Holter study, Holter monitoring indication, atrial and ventricular arrhythmic burden, conduction system disease, and patient-reported symptoms were analyzed. Holter monitoring indication included routine screening as well as for patient symptoms. Atrial and ventricular arrhythmias were categorized as follows: no ectopy, rare or occasional single ectopic beats (1 to <720 beats in 24 hours), frequent single ectopic beats (≥720 beats in 24 hours), nonsustained tachycardia (4 consecutive beats to 30 seconds of arrhythmia), and sustained arrhythmias (>30 seconds of arrhythmia). A clinically significant Holter finding was defined as nonsustained ventricular tachycardia (NSVT) or sustained ventricular tachycardia, atrial fibrillation or flutter, or a new diagnosis of conduction system disease. Holter recordings with clinically significant findings were then reviewed for their impact on patient care. A change in care resulting from a significant finding on Holter monitoring was defined as a study that led directly to a change in clinical medication, an electrophysiologic study, or the implantation of a pacemaker, defibrillator, or permanent loop recorder.
Holter-based arrhythmia burden was analyzed from 2 perspectives. First, each individual Holter recording was analyzed as a separate event. Second, the cumulative data from the ≥1 Holter study from each patient were analyzed to represent arrhythmia burden on the basis of individual patients over the course of the study.
Data were recorded by the principal investigator and analyzed by data management personnel for completeness and accuracy. Any incomplete data, or entries with logical inconsistencies, were returned to the principal investigator for adjudication. All critical variables underwent a 100% check for the accuracy of entry. Ten percent of all other data were inspected for accuracy. The data-entry error rate for this study was 0%. Analyses were performed comparing the effect of mild LV dysfunction as determined by a lower LVEF. Patient demographics and cardiac histories were compared between the 2 groups. Comparisons between groups of Holter study characteristics were also performed (1) at the individual Holter recording level and (2) using combined cumulative results for each patient. Tests of differences in proportions were made using Fisher’s exact test or other chi-square-type test as appropriate. Continuous variables were tested for normality. Comparisons of means were made using Student’s t tests.
Results
Patient demographics and outcomes are listed in Table 1 . A total of 72 pediatric patients with LVNC and preserved LV function were included for analysis. Most of the patients (90%) had LVEFs >55%. The mean age of the population was 13 years, and the cohort with mild LV dysfunction was older than the cohort with normal function (12 vs 18 years, p = 0.005). No patient underwent cardiac transplantation or had a resuscitated sudden cardiac event. There was 1 death in the population, in a patient with a normal ejection fraction, which was sudden in nature. The patient died while sleeping and had not previously reported clinical symptoms of syncope or palpitations.
| Variables | Total (n=72) | Ejection Fraction ≥ 55 (n=65) | Ejection Fraction < 55 (n=7) | P-value |
|---|---|---|---|---|
| Number of Holters | 126 | 112 | 14 | NS |
| Male | 47 (65%) | 42 (65%) | 5 (71%) | NS |
| Race | ||||
| White | 53 (82%) | 46 (71%) | 7 (100%) | NS |
| Black | 15 (23%) | 15 (23%) | 0 | |
| Asian | 3 (4%) | 3 (5%) | 0 | |
| Other | 1 (1%) | 1 (2%) | 0 | |
| Age at last follow up, mean (years) | 13 | 12 ± 5.8 | 18 ± 3.6 | 0.005 |
| Defibrillator | 0 | n/a | n/a | NS |
| Pacemaker | 2 (3%) | 2 (3%) | 0 | NS |
| Syncope | 4 (6%) | 4 (6%) | 0 | NS |
| Death | 1 (1%) | 1 (1%) | 0 | NS |
| Sudden Cardiac Death | 1 (1%) | 1 (1%) | 0 | NS |
| Aborted Sudden Death | 0 | n/a | n/a | NS |
| Transplant | 0 | n/a | n/a | NS |
| Arrhythmia History | ||||
| Atrial Fibrillation | 1 (1%) | 1 (2%) | 0 | NS |
| Supra-ventricular Tachycardia | 1 (1%) | 2 (3%) | 0 | NS |
| Ventricular Arrhythmias | 0 | 0 | 0 | NS |
| History of Conduction System Disease | 2 (3%) | 2 (3%) | 0 | NS |
| Genetic Mutation | ||||
| Positive Genetic Testing | 17 (24%) | 15 (23%) | 2 (29%) | NS |
Arrhythmia findings, evaluating Holter studies as discrete events, are listed in Table 2 . Patients in the cohort with mild dysfunction were older than those with normal function at the time of Holter analysis (18 vs 11 years, p <0.001). Atrial arrhythmias, primarily in the form of rare or occasional premature atrial complexes (PACs), were common (58%) and similar between cohorts. Ventricular ectopy, mostly in the form of rare or occasional ventricular premature complexes (VPCs), were common (29%) and seen more frequently in patients with mild dysfunction compared with those with normal function (56% vs 26%, p = 0.03). Higher grade ectopy, including ventricular couplets and NSVT, was rare (2%). The identification of a predefined significant Holter finding was rare (4%) and not statistically different between cohorts, although all 5 of the significant findings were seen in the cohort with normal LVEFs. Similarly, changes in patient care as the result of Holter monitoring were rare (2%) and included medication titration and pacemaker implantation in 1 patient each, both in the cohort of patients with normal LVEFs.
| Variable | Total (n=126) | Ejection Fraction ≥ 55 (n=112) | Ejection Fraction < 55 (n=14) | P-value |
|---|---|---|---|---|
| Age at time of Holter ( median)(years) | 12 | 11 | 18 | <0.001 |
| Holter Indication Asymptomatic Screening | 117 (93%) | 103 (92%) | 14 (100%) | NS |
| Atrial Arrhythmias | 73 (58%) | 66 (59%) | 7 (50%) | NS |
| Rare/Occasional Premature Atrial Contractions | 66 (52%) | 60 (54%) | 6 (43%) | |
| Frequent Premature Atrial Contractions | 4 (3%) | 4 (4%) | 0 | |
| Atrial Couplets | 8 (6%) | 8 (7%) | 0 | |
| Non-sustained Atrial Tachycardia | 2 (2%) | 1 (1%) | 1 (7%) | |
| Sustained Atrial Tachycardia, Fibrillation or Flutter | 0 | 0 | 0 | |
| Ventricular Arrhythmias | 37 (29%) | 29 (26%) | 8 (57%) | 0.03 |
| Rare/Occasional Ventricular Premature Complexes | 29 (23%) | 21 (19%) | 8 (57%) | |
| Frequent Ventricular Premature Complexes | 8 (6%) | 8 (7%) | 0 | |
| Ventricular Couplets | 6 (5%) | 6 (5%) | 0 | |
| Non-sustained Ventricular Tachycardia | 3 (2%) | 3 (3%) | 0 | |
| Sustained Ventricular Tachycardia | 0 | 0 | 0 | |
| Sinus Node Dysfunction | 2 (2%) | 1 (1%) | 1 (7%) | NS |
| Heart Block | 8 (6%) | 8 (7%) | 0 | NS |
| First degree AV block | 0 | 0 | 0 | |
| Mobitz Type I (non-significant) | 7 (6%) | 7 (6%) | 0 | |
| AV block other than above | 1 (1%) | 1 (1%) | 0 | |
| Patient Symptoms | 12 (10%) | 8 (7%) | 4 (29%) | 0.03 |
| Significant Holter Finding | 5 (4%) | 5 (4%) | 0 | NS |
| Non-sustained Ventricular Tachycardia | 3 (2%) | 3 (3%) | 0 | |
| Sustained Ventricular Tachycardia | 0 | 0 | 0 | |
| Sustained Atrial Fibrillation/Atrial Flutter | 0 | 0 | 0 | |
| Conduction System Disease | 1 (1%) | 1 (1%) | 0 | |
| Focal Atrial Tachycardia | 1 (1%) | 1 (1%) | 0 | |
| Change in Care | 3 (2%) | 3(3%) | 0 | NS |
| Pacemaker Implant | 1 (1%) | 1 (1%) | 0 | |
| Defibrillator Implant | 0 | 0 | 0 | |
| EP Study | 1 (1%) | 1 (1%) | 0 | |
| Loop Recorder | 0 | 0 | 0 | |
| Change in Medication | 1 (1%) | 1 (1%) | 0 |
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