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      Investigation of Catecholaminergic Polymorphic Ventricular Tachycardia Children in China: Clinical Characteristics, Delay to Diagnosis, and Misdiagnosis


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          To the Editor: Catecholaminergic polymorphic ventricular tachycardia (CPVT) often occurs in children or adolescents without organic heart diseases. It is a rare malignant arrhythmic disorder with hereditary features characterized by exercise- or emotional stress-induced ventricular arrhythmias, especially bidirectional/polymorphic ventricular tachycardia (VT), syncope, or sudden death.[1] The mortality rate of symptomatic CPVT patients before 30 years of age is 31%,[2] and an early treatment with beta-blockers could effectively improve their prognosis.[3] Therefore, getting a confirmed diagnosis of CPVT in time is of utmost importance. On this context, this study summarizes the clinical characteristics and diagnosis of pediatric cases with CPVT. This study was approved by the Ethics Committee of The First Hospital of Tsinghua University (No. HX200901) and was conducted in accordance with the 1964 Declaration of Helsinki. The study involves 12 CPVT cases [Table 1], including eight males and four females, in which ten cases had a history of recurrent syncope after emotional distress or exercise. Except for two cases whose CPVT were confirmed by HOLTER monitoring, the remaining ten cases underwent treadmill exercise tests. Bidirectional VT or polymorphic VT was induced in all these cases during treadmill exercise test in which three of them showed concurrent atrial arrhythmias. Genetic test was performed in 11 cases and positive results were identified in all of them (RYR2 gene mutation in nine cases and CASQ2 gene mutation in the remaining two cases). Among the 12 CPVT cases, nine cases were given long-term oral propranolol therapy, whereas for the remaining three cases, long-term oral metoprolol was given. During the follow-up period of 0.92 ± 0.80 years (0.08–2.42 years), seven patients were observed to be free from symptoms or discomforts such as syncope, and three patients had significantly decreased the frequency of syncope, whereas one patient died suddenly during the course of oral metoprolol therapy while he was playing. Table 1 Characteristics of CPVT cases in the series (n = 12) Characteristics n Number of males 8 Syncope as first symptom 9 Number with SSS 6 Number with atrial arrhythmias 5 Treadmill exercise test 10  Treadmill exercise test positive 10 Genetic test 11  Genotype positive 11 Drug therapy (β-blocker) 12  Propranolol 9  Metoprolol 3 PM therapy 1 CPVT: Catecholaminergic polymorphic ventricular tachycardia; SSS: Sick sinus syndrome; PM: Pacemaker. The mean age at the onset of CPVT symptoms for the 12 cases was 8.4 ± 3.2 years (4.0–13.7 years). The mean age at diagnosis for these 12 cases was 10.7 ± 2.3 years (7.0–14.0 years). Mean duration between the onset of symptoms and diagnosis was 2.4 ± 1.7 years (0.04–5.0 years) [Figure 1]. Among the 12 cases diagnosed in our center, nine cases were presented typical CPVT clinical manifestations. However, only two cases were suspected as CPVT when diagnosed in other hospitals. All other cases were misdiagnosed in other hospitals in which three cases were misdiagnosed as syncope with cause to be determined, five cases were misdiagnosed as complex arrhythmias, and two cases were misdiagnosed as epilepsy. Figure 1 Distribution for the age of onset of symptoms (dark gray line) and the age at diagnosis (light gray line) for 12 cases of CPVT. Delay of diagnosis occurred in most of the pediatric CPVT patients. CPVT: Catecholaminergic polymorphic ventricular tachycardia. Delayed diagnosis and even misdiagnosis for CPVT are not uncommon. A multicenter study reported that the mean duration between the first clinical episode and diagnosis for 226 CPVT cases under 19 years was 0.5 year.[4] Among them, 38% had more than 1-year delay for diagnosis, whereas 56% was initially misdiagnosed. For some of the Chinese pediatric CPVT patients (35 cases from the relevant studies or reports in the CNKI database published from 2004 to 2017), the delay of diagnosis is 3.0 years (0.1–36.0 years). Only 19.5% was diagnosed within one year. Severe delay of diagnosis and misdiagnosis exist for CPVT, and the possible reasons are as follows. The foremost cause could be due to the lack of knowledge and inadequate recognition of CPVT. A study in the form of questionnaire survey was accomplished to investigate the level of understanding for etiologies of sudden death in the young among 614 Canadian medical students and recent graduates (within 5 years of graduation). The results showed that only 30% answered had adequate understanding and recognition of CPVT.[5] Second, some patients have quite concealed symptoms and it is quite difficult to get electrocardiogram recording during the syncope episode. Patients usually have normal resting electrocardiogram, echocardiogram, and intracardiac electrophysiologic study. These might contribute to misdiagnosis or no confirmed diagnosis of CPVT. Third, due to the low prevalence of CPVT and its most common symptom, i.e., syncope, tends to be diagnosed as epilepsy or vasovagal syncope which has a higher prevalence. Severe delay of diagnosis and even misdiagnosis of CPVT are not uncommon due to some reasons. Improving the understanding of CPVT, paying more attention to explore the relationship between syncope and exercise or emotional stress, and performing treadmill exercise test might help to confirm the diagnosis. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship This work was supported by a grant from the Dr. Wu Shun De's Medical Science Research Fund (No. 20240000811). Conflicts of interest There are no conflicts of interest.

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          Incidence and risk factors of arrhythmic events in catecholaminergic polymorphic ventricular tachycardia.

          The pathophysiological background of catecholaminergic polymorphic ventricular tachycardia is well understood, but the clinical features of this stress-induced arrhythmic disorder, especially the incidence and risk factors of arrhythmic events, have not been fully ascertained. The outcome in 101 catecholaminergic polymorphic ventricular tachycardia patients, including 50 probands, was analyzed. During a mean follow-up of 7.9 years, cardiac events defined as syncope, aborted cardiac arrest, including appropriate discharges from implantable defibrillators, or sudden cardiac death occurred in 27 patients, including 2 mutation carriers with normal exercise tests. The estimated 8-year event rate was 32% in the total population and 27% and 58% in the patients with and without beta-blockers, respectively. Absence of beta-blockers (hazard ratio [HR], 5.48; 95% CI, 1.80 to 16.68) and younger age at diagnosis (HR, 0.54 per decade; 95% CI, 0.33 to 0.89) were independent predictors. Fatal or near-fatal events defined as aborted cardiac arrest or sudden cardiac death occurred in 13 patients, resulting in an estimated 8-year event rate of 13%. Absence of beta-blockers (HR, 5.54; 95% CI, 1.17 to 26.15) and history of aborted cardiac arrest (HR, 13.01; 95% CI, 2.48 to 68.21) were independent predictors. No difference was observed in cardiac and fatal or near-fatal event rates between probands and family members. Cardiac and fatal or near-fatal events were not rare in both catecholaminergic polymorphic ventricular tachycardia probands and affected family members during the long-term follow-up, even while taking beta-blockers, which was associated with a lower event rate. Further studies evaluating concomitant therapies are necessary to improve outcome in these patients.
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            Catecholaminergic polymorphic ventricular tachycardia in children: analysis of therapeutic strategies and outcomes from an international multicenter registry.

            Catecholaminergic polymorphic ventricular tachycardia is an uncommon, potentially lethal, ion channelopathy. Standard therapies have high failure rates and little is known about treatment in children. Newer options such as flecainide and left cardiac sympathetic denervation are not well validated. We sought to define treatment outcomes in children with catecholaminergic polymorphic ventricular tachycardia.
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              Sudden unexplained death: heritability and diagnostic yield of cardiological and genetic examination in surviving relatives.

              Sudden death mostly follows from cardiac disorders that elicit lethal ventricular arrhythmias. In young individuals, it often remains unexplained because history and/or postmortem analysis are absent or provide no clue. Because such sudden unexplained deaths (SUDs) may have heritable causes, cardiological and genetic assessment of surviving relatives of SUD victims may reveal the underlying disease and unmask presymptomatic carriers. We aimed to establish the diagnostic yield of such assessments. We investigated 43 consecutive families with > or =1 SUD victim who died at or =2 SUD victims < or =40 years of age. The resting/exercise ECG had a high diagnostic yield. These efforts unmasked 151 presymptomatic disease carriers (8.9 per family). Examination of relatives of young SUD victims has a high diagnostic yield, with identification of the disease in 40% of families and 8.9 presymptomatic carriers per family. Simple procedures (examining many relatives) and routine tests (resting/exercise ECG) constitute excellent diagnostic strategies. Molecular genetics provide strong supportive information.

                Author and article information

                Chin Med J (Engl)
                Chin. Med. J
                Chinese Medical Journal
                Medknow Publications & Media Pvt Ltd (India )
                05 December 2018
                : 131
                : 23
                : 2864-2865
                [1]Department of Pediatric Cardiology, Heart Center, The First Hospital of Tsinghua University (Beijing Huaxin Hospital), Beijing 100016, China
                Author notes
                Address for correspondence: Prof. Xiao-Mei Li, Department of Pediatric Cardiology, Heart Center, The First Hospital of Tsinghua University (Beijing Huaxin Hospital), No. 6, Jiuxianqiao 1 st Road, Chaoyang District, Beijing 100016, China E-Mail: li-xiaomei@ 123456mail.tsinghua.edu.cn
                Copyright: © 2018 Chinese Medical Journal

                This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.



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