Catecholaminergic Polymorphic Ventricular Tachycardia, a Chameleon in Clinical Practice

Objectives: We report the case of a 9-year-old boy who was admitted to our institution with a history of convulsions. At the age of 5 years, the boy was reported to suffer from repeated episodes of muscular hypotonia and enuresis while watching television. Initial electroencephalography in an outpatient setting showed no epileptoform activity. Due to recurring events an anticonvulsive therapy with valproic acid was started. In 2018, three such events were observed so additional electroencephalography was performed. During hospitalization one episode of ventricular tachycardia with a maximum heart frequency of 240 bpm was recorded which resulted in admission to our pediatric heart center.

Methods: Previous medical history with clinical and familial anamnesis reviewed. Extended laboratory (routine and hormonal) and cardiac (12-lead ECGs, Holter’s ECG, echocardiography, and treadmill stress test) investigations were performed to facilitate the diagnosis.

Result: Family history was negative for sudden cardiac death (SCD) or known congenital cardiac conditions. Clinically the patient was without pathological findings. Laboratory tests showed normal values for electrolytes, hormonal or metabolic parameter. Cardiac function evaluated by echocardiography showed a normal function, normal atrial and ventricular dimensions without dyskinesia. Serial 12-lead electrocardiogram (ECG) in rest showed no abnormalities. Cardiac stress test was aborted by the patient due to feeling unwell with a maximum reached heart rate of 110 bmp. Holter’s monitoring revealed multifocal premature ventricular contractions starting from a heart rate of 125 bpm, which suggested the diagnosis of catecholaminergic polymorphic ventricular tachycardia (CPVT). This diagnosis was confirmed by positive genetic testing.

Conclusion: CPVT is an underdiagnosed, potentially life-threatening hereditary arrhythmia. Molecular autopsies revealed that genetic mutation linked to CPVT can be found in up to 15% of SCD. The prevalence is estimated as 1:10,000 in Europe. It is therefore important that this differential diagnosis may be considered in patient with recurring syncope without epileptoform activity in electroencephalography. Holter’s ECG is useful, especially if the patient stress test is inconclusive due to incomplete test.