50 Years of Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) – Time to Explore the Dark Side of the Moon

Despite significant progress in understanding catecholaminergic polymorphic ventricular tachycardia (CPVT), there are still multiple uncertainties and gaps in our knowledge. Like the dark side of the moon, we cannot see them directly. Unfortunately, clinicians must make diagnostic and therapeutic decisions without solid evidence. Instead of summarising the current state of science and reiterating the guidelines, we review difficulties in understanding the disease mechanism, diagnosis and therapy. Highlighting these truths helps to avoid misconceptions, think clearly about our patients and direct future research efforts. It has become clear that CPVT encompasses more than just uniformly expressed ryanodine receptor mutations leading to bidirectional ventricular tachycardia, rather it is a disease caused by different genetic mutations, overlapping with other entities and possibly affecting not only the heart. Treatment in addition to beta blockers is often necessary: flecainide and left cardiac sympathetic denervation are therapies that come before consideration of defibrillator implantation and new treatment options are on the horizon

Long‐term outcomes of pacemaker implantation in children with univentricular versus complex biventricular surgical repair

Abstract Objective Pacing in a univentricular circulation has been associated with worsened outcomes. We investigated the long‐term outcomes of pacing in children with a univentricular circulation compared to a complex biventricular circulation. We also identified predictors of adverse outcomes. Methods A retrospective study of all children with major congenital heart disease who underwent pacemaker implantation under the age of 18 years between November 1994 and October 2017. Results Eighty‐nine patients were included; 19 with a univentricular and 70 with a complex biventricular circulation. A total of 96% of pacemaker systems were epicardial. Median follow up was 8.3 years. The incidence of adverse outcome was similar between the two groups. Five (5.6%) patients died and two (2.2%) underwent heart transplantation. Most adverse events occurred within the first 8 years after pacemaker implantation. Univariate analysis identified five predictors of adverse outcomes in the patients in the biventricular but none in the univentricular group. The predictors of adverse outcome in the biventricular circulation were a right morphologic ventricle as the systemic ventricle, age at first congenital heart disease (CHD) operation, number of CHD operations, and female gender. The nonapical lead position was associated with a much higher risk of an adverse outcome. Conclusions Children with a pacemaker and a complex biventricular circulation have similar survival to the ones with a pacemaker and a univentricular circulation. The only modifiable predictor was the epicardial lead position on the paced ventricle, emphasizing the importance of apical placement of the ventricular lead

Ten-year experience in atenolol use and exercise evaluation in children with genetically proven long QT syndrome

Background: Due to its availability, atenolol is the primary beta-blocker used in Australia for children with long QT syndrome. There is limited data on long-term follow-up of its use. Methods: A single-tertiary-center, retrospective, observational study investigating all children and adolescents who had genetically proven long QT syndrome type 1 (LQT1) and type 2 (LQT2) was conducted. Their pretreatment exercise tests were evaluated for QTc intervals into the recovery phase of exercise. Results: Eighty six patients were identified (LQT1, 67, and LQT2, 19) from 2004 to 2014. The majority (86%) of patients were initially referred for family screening. Atenolol was administered at a mean dose of 1.58 ± 0.51 mg/kg/day. During the median follow-up period of 4.29 years, only one proband developed ventricular arrhythmia whilst taking atenolol, No patient had cardiac arrest or aborted cardiac arrest. With respect to side effects of atenolol, only two patients had intolerable side effects necessitating changes of medication. Evaluation of exercise tests (pretreatment) demonstrated that corrected QT (QTc) intervals at 2â3 min into the recovery phase of exercise were significantly prolonged for LQT1 patients. LQT1 patients with transmembrane mutation had longer QTc intervals than their C-terminus mutation counterparts, reaching statistical significance at 3 min into the recovery phase of exercise. Conclusions: Atenolol is an effective treatment for genetically proven LQT1 and LQT2 children and adolescents, with good tolerability. In LQT1 patients, QTc intervals at 2â3 min into the recovery phase of exercise were significantly prolonged, particularly in patients with transmembrane mutations. Keywords: Long QT syndrome, Atenolol, Beta-blocker, Exercise, Pediatric

Clinical Outcomes and Modes of Death in Timothy Syndrome: A Multicenter International Study of a Rare Disorder

Objectives: The objective of this study was to evaluate contemporary clinical outcomes and identify triggers for arrhythmias or sudden death in an international cohort of Timothy Syndrome (TS) patients including those with novel TS-associated CACNA1C mutations. Background: TS is an extremely rare genetic disorder of the L-type cardiac channel Cav1.2 encoded by CACNA1C. The syndrome is characterized by multisystem abnormalities consisting of QT prolongation, congenital heart defects, syndactyly, facial dysmorphism, and neurological symptoms. Methods: Patients diagnosed with TS between January 1, 1994, and April 1, 2016, from 12 international tertiary care pediatric centers were included in this retrospective study. Data were gathered via survey from the patients’ electrophysiologists. Results: Seventeen patients diagnosed with TS were identified. Length of follow-up was 4.9 years (range 3.0 to 19.0 years). Mean QTc was 640 ms (range 500 to 976 ms). All patients were treated with beta-blockers; 13 patients (76%) were also treated with an implantable defibrillator. Eleven patients experienced an episode of aborted cardiac arrest, 6 associated with general anesthesia and 2 with hypoglycemia. Four patients died suddenly due to ventricular fibrillation, 2 of whom had associated hypoglycemia. Conclusions: This study shows that mortality in TS patients is due to multifactorial mechanisms, which include ventricular arrhythmias, pulseless electrical activity, and hypoglycemia. A simple nomenclature for ongoing studies of TS and related syndromes is described. A worldwide prospective registry is needed for continued exploration of this syndrome

Position Statement on the Management of Cardiac Electrophysiology and Cardiac Implantable Electronic Devices in Australia during the COVID-19 Pandemic: A Living Document

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time