Bradycardia Is a Specific Phenotype of Catecholaminergic Polymorphic Ventricular Tachycardia Induced by RYR2 Mutations

Objective Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal inherited disease characterized by ventricular arrhythmias induced by physical exercise or emotional stress. The major cause of CPVT is mutations in RYR2, which encodes the cardiac ryanodine receptor channel. Recent a...

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Bibliographic Details
Published in:Internal Medicine 2018/07/01, Vol.57(13), pp.1813-1817
Main Authors: Miyata, Kazuaki, Ohno, Seiko, Itoh, Hideki, Horie, Minoru
Format: Article
Language:English
Subjects:
Adolescent
Bradycardia
Bradycardia - genetics
Cardiac arrhythmia
catecholaminergic polymorphic ventricular tachycardia
Child
Child, Preschool
Coronary artery disease
EKG
Electrocardiography
Female
Genetic Predisposition to Disease
Heart diseases
Hereditary diseases
Humans
Infant
Infant, Newborn
Internal medicine
Long QT syndrome
Male
Mutation
Original
Patients
Phenotype
Phenotypes
Physical exercise
Ryanodine Receptor Calcium Release Channel - genetics
Ryanodine receptors
RYR2 mutation
Tachycardia
Tachycardia, Ventricular - genetics
Ventricle
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Summary:Objective Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal inherited disease characterized by ventricular arrhythmias induced by physical exercise or emotional stress. The major cause of CPVT is mutations in RYR2, which encodes the cardiac ryanodine receptor channel. Recent advances in sequencing technology have yielded incidental findings of RYR2 variants in other cardiac diseases. Analyzing the characteristics of RYR2 variants related to CPVT will be useful for differentiation from those related to other cardiac diseases. We examined the phenotypic characteristics of patients with RYR2 variants. Methods Seventy-nine probands carrying RYR2 variants whose diagnoses were either CPVT (n=68) or long QT syndrome (LQTS; n=11) were enrolled. We compared the characteristics of the electrocardiogram (ECG) and the location of the RYR2 mutations-N-terminal (NT), central region (CR) or C-terminal (CT)-between the two patient groups. Results Using the ECGs available from 53 probands before β-blocker therapies, we analyzed the heart rates (HRs). CPVT probands showed bradycardia more frequently (25/44; 57%) than LQTS probands (1/9; 11%; p=0.024). In CPVT patients, 20 mutations were located in NT, 25 in CR and 23 in CT. In LQTS patients, 5 mutations were located in NT, 2 in CR and 4 in CT. There were no significant differences in the locations of the RYR2 mutations between the phenotypes. Conclusion Bradycardia was highly correlated with the phenotype of CPVT. When a clinically-diagnosed LQTS patient with bradycardia carries an RYR2 mutation, we should be careful to avoid making a misdiagnosis, as the patient may actually have CPVT.
ISSN:0918-2918
1349-7235
DOI:10.2169/internalmedicine.9843-17