|Year : 2017 | Volume
| Issue : 1 | Page : 32-36
Incidence of cardiac arrhythmia in children with dilated cardiomyopathy
Ali M Abd El Mohsen, Manal A Antonios, Mohamed M Elbiomy
Department of Pediatrics, Faculty of Medicine, Alexandria University, Alexandria, Egypt
|Date of Submission||26-Mar-2017|
|Date of Acceptance||18-Apr-2017|
|Date of Web Publication||12-Jul-2017|
Manal A Antonios
Lecturer of Pediatrics, Department of Pediatrics, Faculty of Medicine, Alexandria University, Alexandria
Source of Support: None, Conflict of Interest: None
Background To date, no study has accurately characterized the frequency of arrhythmia in children with dilated cardiomyopathy (DCM). Recent studies have reported that children with DCM are at a higher risk for life-threatening arrhythmias than was previously appreciated.
Aim This study attempted to assess the incidence of and to identify the risk for life-threatening arrhythmias in children with DCM.
Patients and methods All patients with DCM who were attending the cardiology clinic in Alexandria University Children’s Hospital were enrolled in the study. All data about demographics, presenting symptoms at time of diagnosis and medications were collected. Clinical, echocardiographic and ECG parameters, and 24-h Holter records of the patients were evaluated.
Results Six patients experienced arrhythmia, representing a rate of 20.7%, with more prevalence among female patients. Only one patient experienced life-threatening arrhythmia (supra-ventricular tachycardia, SVT), representing a rate of 3.4%. Significant risk factors of arrhythmias were disturbed electrolytes levels (P=0.008), abnormal diagnostic left ventricular dimensions (P=0.006) and longer QRS duration (P<0.001).
Conclusion Wider-scale studies should be conducted to further evaluate the role of patient’s age, age at diagnosis of DCM and diagnostic echocardiographic variables on the incidence of arrhythmia. The high incidence of arrhythmia associated with prolonged QRS duration should undergo further investigation.
Keywords: arrhythmia, dilated cardiomyopathy, ECG
|How to cite this article:|
Abd El Mohsen AM, Antonios MA, Elbiomy MM. Incidence of cardiac arrhythmia in children with dilated cardiomyopathy. Alex J Pediatr 2017;30:32-6
|How to cite this URL:|
Abd El Mohsen AM, Antonios MA, Elbiomy MM. Incidence of cardiac arrhythmia in children with dilated cardiomyopathy. Alex J Pediatr [serial online] 2017 [cited 2018 Sep 26];30:32-6. Available from: http://www.ajp.eg.net/text.asp?2017/30/1/32/210442
| Introduction|| |
Cardiac diseases in children continue to be an important cause of morbidity and mortality. Pediatric cardiomyopathies are rare but serious and often life-threatening conditions. Dilated cardiomyopathy (DCM) is the most common cause of heart failure in children.
The estimated annual incidence of DCM in children is 0.57 cases per 100 000 . Despite numerous advances in the treatment of adults with DCM, outcomes remain poor in children with this diagnosis, with an incidence of death or transplantation of 31% at 1 year and 46% at 5 years .
The main adverse events affecting the prognosis for DCM patients are the occurrence of malignant ventricular arrhythmias and sudden death and the progression towards heart failure .
Dysregulation of autonomic nervous system function and impaired homogeneity of myocardial repolarization are two major mechanisms for the genesis of ventricular arrhythmias .
Diverse causes can result in DCM with electric instability and fall into general categories of inflammatory, infectious, hereditary and infiltrative processes. Cardiac presentation associated with these conditions is distinct from more common causes of DCM such as viral myocarditis, valvular dysfunction, inborn errors of metabolism or substance abuse .
Assessment of arrhythmic risk is still a challenge. Better characterization of patients using additional parameters should be able to detect those with a higher or lower risk for arrhythmic events  ([Figure 1]).
|Figure 1 The main parameters proposed in order to better characterize arrhythmic risk .|
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Most pediatric studies focusing on arrhythmias in this population are limited by sample size, low event rate (or incomplete capture of the event) and insufficient arrhythmia data for analysis .
| Patients and methods|| |
This study was conducted during a period of 3 years (2012–2014) on all children suffering from DCM who were attending the cardiology clinic in Alexandria University Children’s Hospital.
The following data were collected from all patients enrolled in this study:
- Demographic data including sex, presenting age, age at diagnosis of DCM and duration of disease.
- Diagnostic echocardiography and presenting symptoms at time of diagnosis, syncope/near syncope, palpitation, dyspnea, chest pain, dizziness or orthopnea.
- Previous hospitalizations and medications received and all cardiac medications prescribed to those patients.
All patients enrolled in this study were assessed according to the following approach.
All patients underwent complete physical examination with special emphasis on the cardiac examination.
- Twelve-lead ECG measurements of key intervals (PR and QRS) from all available electrocardiograms.
- Twenty-four-hour ECG recording (Holter monitoring).
In patients who developed life-threatening arrhythmia, ventricular function from the most recent echocardiogram before the event was measured.
| Results|| |
Between January 2012 and December 2014, 29 patients with the diagnosis of DCM were identified. The average of patients was 4.55±3.29 years. Demographics, baseline echocardiographic measurements and medications used are summarized in [Table 1].
Data from 24-h ECG recording of the patients are summarized in [Table 2].
|Table 2 Descriptive analysis of the studied cases according to 24-h ECG recording (Holter monitoring) (n=29)|
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It was observed that female sex has a higher incidence in patients with arrhythmia, which were recorded in 66.7%, as compared with an incidence of 34.8% among patients without arrhythmia. Yet, this female sex predominance as a risk factor for arrhythmia was not statistically significant (P=0.198). It was also observed that the mean age in patients with arrhythmia is slightly higher than the mean of age in patients without arrhythmia (4.79±4.08 vs. 4.49±3.16 years); this observation was not statistically significant (P=0.850) ([Table 3]).
|Table 3 Comparison between the two studied groups according to sex and age|
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It was observed that the incidence of disturbed electrolytes levels among patients with arrhythmia (66.7%) was significantly higher compared with 8.7% in patients without arrhythmia (P=0.008) ([Table 4]).
|Table 4 Comparison between the two studied groups according to serum electrolytes level|
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It was observed that the use of diuretics (83.3%), digoxin (66.7%), l-carnitine (83.3%) among patients with arrhythmia was higher than the use of these drugs in patients without arrhythmia. Meanwhile, the use of angiotensin-converting enzyme (ACE) inhibitors (91.3%) and acetyl salicylates (34.8%) among patients without arrhythmia was higher as compared with the use in patients with arrhythmia. These results were not statistically significant ([Table 5]).
|Table 5 Comparison between the two studied groups according to cardiac medications prescribed to the patients|
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Patients with abnormal diagnostic ejection fraction (EF%) showed a higher incidence of arrhythmia (83.3%) compared with those patients with normal EF%, who showed an incidence of 16.7% of arrhythmia. The incidence of abnormal EF% among patients with arrhythmia (83.3%) was higher compared with 78.3%patients without arrhythmia. These observations were not statistically significant (P=0.553). It was observed that the incidence of abnormal left ventricular diameter at end diastole (LVEDd) and left ventricular diameter at end systole (LVEDs) among patients with arrhythmia (100.0%) was significantly higher compared with patients without arrhythmia (34.8%). This observations were statistically significant (P=0.006) ([Table 6]).
|Table 6 Comparison between the two studied groups according to diagnostic echocardiography findings|
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It was observed that the incidence of prolonged QRS duration among patients with arrhythmia (83.3%) was significantly higher when compared with patients without arrhythmia (4.3%). This observation was statistically significant (P<0.001) ([Table 7]).
|Table 7 Comparison between the two studied groups according to QRS duration|
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| Discussion|| |
DCM is an important cause of heart failure in children, with reported 5-year heart transplant-free survival of ∼50% .
In this study, we investigated the rate of fatal and nonfatal life-threatening arrhythmias in children with DCM and identified risk factors for arrhythmias in this population.
The total number of included patients was 29 (17 boys and 12 girls). The patients’ mean age was 4.55±3.29 years. The mean duration of follow up was 3.93±2.77 years, and 72.4% of the patients were previously hospitalized.
The overall incidence of occurrence of arrhythmias was 20.7%, with more prevalence among girls (66.7%). Overall, 10.3% (three) patients had isolated ventricular events and 10.3% (three) patients had isolated supraventricular events. Only one patient experienced life-threatening arrhythmia (supra-ventricular tachycardia, SVT), representing a rate of 3.4%.
In the study conducted by Duy et al. , it was found that the incidence of all arrhythmic events was 19.1%. Similarly, Hegazy and Lotfy  found the incidence to be 19.9%. Many studies have demonstrated the incidence of life-threatening arrhythmias in such patients to fall somewhere between 1%  and 3% .
None of the recently published researches succeeded to prove sex predominance, as while Duy et al.  showed a female predominance in the incidence of arrhythmia (57%), Pahl et al.  demonstrated a male predominance (54.3%).
In the current study, 66.7% of patients with arrhythmia had disturbed electrolytes level, especially hypokalemia and hypocalcemia. Our studied patients received diuretics and digoxin and no one reported to have received potassium supplements. Zipes and Jose  found that electrolyte imbalance especially hypokalemia and hypomagnesemia (often related to diuretics use) can play a role in arrhythmogenesis in patients with DCM.
Among the six patients with arrhythmia included in the study, digoxin was used by four (66.7%) patients. The same percentage with ACE inhibitors, whereas one (16.7%) patient only had been prescribed amiodarone.
In Pahl et al.’s  study on 35 patients with arrhythmia, 88.6% had used digoxin, 20% had received ACE inhibitors and 20% were prescribed amiodarone.
Many studies revealed that EF is a strong predictor of sudden death in adults with DCM but has not been useful when evaluating children . In the current study, findings confirmed that there was no association between EF and risk of arrhythmia. These results are in agreement with the study Dimas et al.  that reported no statistically significant difference between patients with and without arrhythmias in EF.
In the present study, abnormal LVEDd and LVEDs at diagnosis were significant risk factors for developing arrhythmia among the patients with DCM. All patients with arrhythmia had abnormal diagnostic left ventricular dimensions compared with 34.8% of patients without arrhythmia. The mean of LVEDd in patients with arrhythmia was higher compared with the mean in those without arrhythmia (3.42±0.96 vs. 3.23±0.87 cm), whereas the mean of LVEDs in patients with arrhythmia was higher compared with those without arrhythmia (2.35±1.03 vs. 2.32±0.81 cm).
In a study by Han et al.  on 68 children with DCM, it was found that the mean of LVED in the arrhythmia group (74±6 mm) was significantly greater than that in the nonarrhythmia group (61±3 mm) (P<0.05).
Interestingly, we found that the risk for developing arrhythmia is significantly higher when QRS duration was prolonged. Duy et al.  showed that an increased QRS duration z-score was associated with increased odds of developing arrhythmias in univariate and multivariate logistic regression.
One limitation of this study was the fewer of number of patients recruited. This might cause the sample size to be insufficient.
| Conclusion|| |
Children with DCM are at a higher risk for arrhythmias than was previously appreciated. Wider-scale studies should be conducted to further evaluate the role of patient’s age, age at diagnosis of DCM and diagnostic echocardiographic variables on the incidence of arrhythmia. Close monitoring of electrolytes and the prompt correction of any abnormalities especially in children using diuretics or digoxin is needed. Furthermore, the high incidence of arrhythmia associated with prolonged QRS duration that was encountered in the present study should undergo further investigation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]