Clinical characteristics of three Czech families with catecholaminergic polymorphic ventricular tachycardia and pilot results of RyR2 gene mutation analysis
Abstract
Aim: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare hereditary arrhythmia. The onset of clinical symptoms usually occurs during childhood, and is typically related to stress.
The aim of our study is to provide clinical characteristics of three Czech families with CPVT and pilot results of mutation analysis of the RyR2 gene. Methods: The subjects and their relatives are investigated at the participating departments.
They undergo basic clinical investigation, with their history-taking focused on possible CPVT symptoms, i.e. syncopes during stress. Bicycle ergometry is performed to obtain ECG recordings during adrenergic stimulation.
In all the investigated individuals, blood samples are taken for DNA isolation, with mutation analysis of the RyR2 gene started in subjects. Results: To date, three families (11 adults and five children) have been investigated.
In three CPVT patients, the indication for examination was syncope during stress. The diagnosis was confirmed with bicycle ergometry-induced polymorphic ventricular tachycardia.
The arrhythmia was not induced in any other relatives. All three affected individuals were treated with a beta-blocker, with one having a cardioverter-defibrillator implanted because of recurrent syncopes.
Sequence changes c.14101-6A>G and 14101-21A>G close to 3'-end of intron 94-95, and in 14231+12A>C close to 5'-end of intron 95-96 were detected in one subject. The detected sequence changes have not been included in the CPVT mutation database and published yet.
Conclusions: CPVT is a rare disease with a high risk of sudden death. This diagnosis must be considered in all cases of exercise-related syncope.
A resting electrocardiogram is completely unremarkable. For the confirmation of the diagnosis an exercise test is necessary.
Mutation analysis of related genes may reveal asymptomatic individuals in whom beta-blocker therapy is recommended.