Background Catecholaminergic polymorphic ventricular tachycardia (CPVT) 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 (LCSD) are not well validated. We sought to define treatment outcomes in children with CPVT. Methods and Results This is a Pediatric and Congenital Electrophysiology Society (PACES) multicenter, retrospective cohort study of CPVT patients diagnosed before 19 years of age. The cohort included 226 patients, including 170 probands and 56 relatives. Symptomatic presentation was reported in 176 (78%). Symptom onset occurred at 10.8 (IQR 6.8–13.2) years with a delay to diagnosis of 0.5 (0–2.6) years. Syncope (p<0.001), cardiac arrest (p<0.001) and treatment failure (p=0.008) occurred more often in probands. Beta-blockers were prescribed in 205 of 211 patients (97%) on medication, and 25% experienced at least one treatment failure event. Implantable cardioverter defibrillators (ICDs) were placed in 121 (54%) and was associated with electrical storm in 22 (18%). Flecainide was used in 24% and LCSD in 8%. Six deaths (3%) occurred during a cumulative follow-up of 788 patient-years. Conclusions This study demonstrates a malignant phenotype and lengthy delay to diagnosis in CPVT. Probands were typically severely affected. Beta-blockers were almost universally initiated; however, treatment failure, non-compliance and sub-therapeutic dosing were often reported. ICDs were common despite numerous device-related complications. Treatment failure was rare in the quarter of patients on flecainide. LCSD was not uncommon although the indication was variable.

This large, multicentre study identifies contemporary challenges related to the diagnosis and prognostication of CPVT patients. Structural modelling of RyR2 can improve our understanding severe CPVT phenotypes. Wakeful rest, rather than exertion, often precipitated life-threatening cardiac events.

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Background— The effectiveness of implantable cardioverter-defibrillator (ICD) therapy for the management of catecholaminergic polymorphic ventricular tachycardia (VT) in young patients is not known. ICD discharges are not always effective and inappropriate discharges are common, both resulting in morbidity and mortality. Methods and Results— This is a multicenter, retrospective review of young patients with catecholaminergic polymorphic VT and ICDs from 5 centers. ICD discharges were evaluated to determine arrhythmia mechanism, appropriateness, efficacy of therapy, and complications. A total of 24 patients were included. Median (interquartile range) ages at onset of catecholaminergic polymorphic VT symptoms and ICD implant were 10.6 (5.0–13.8) years and 13.7 (10.7–16.3) years, respectively. Fourteen patients received 140 shocks. Ten patients (42%) experienced 75 appropriate shocks and 11 patients (46%) received 65 inappropriate shocks. On actuarial analysis, freedom from appropriate shock at 1 year after ICD implant was 75%. Of appropriate shocks, only 43 (57%) demonstrated successful primary termination. All successful appropriate ICD discharges were for ventricular fibrillation. No episodes of polymorphic VT or bidirectional VT demonstrated successful primary termination. The adjusted mean (95% confidence interval) cycle length of successful discharges was significantly shorter than unsuccessful discharges (168 [152–184] ms versus 245 [229–262] ms; adjusted P =0.002). Electrical storm occurred in 29% (4/14) and induction of more malignant ventricular arrhythmias in 36% (5/14). There were no deaths. Conclusions— ICD efficacy in catecholaminergic polymorphic VT depends on arrhythmia mechanism. Episodes of ventricular fibrillation were uniformly successfully treated, whereas polymorphic and bidirectional VT did not demonstrate successful primary termination. Inappropriate shocks, electrical storm, and ICD complications were common.