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Heart Rhythm O2 2021 Apr 13;2(2):149-159. Epub 2021 Mar 13.

Department of Cardiology, Amsterdam UMC, University of Amsterdam, Heart Center, Amsterdam, The Netherlands.

Background: Adult long QT syndrome (LQTS) patients have inadequate corrected QT interval (QTc) shortening and an abnormal T-wave response to the sudden heart rate acceleration provoked by standing. In adults, this knowledge can be used to aid an LQTS diagnosis and, possibly, for risk stratification. However, data on the diagnostic value of the standing test in children are currently limited. Read More

Heart Rhythm O2 2021 Feb 22;2(1):89-106. Epub 2021 Jan 22.

Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio.

Long QT syndrome (LQTS) is a cardiovascular disorder characterized by an abnormality in cardiac repolarization leading to a prolonged QT interval and T-wave irregularities on the surface electrocardiogram. It is commonly associated with syncope, seizures, susceptibility to torsades de pointes, and risk for sudden death. LQTS is a rare genetic disorder and a major preventable cause of sudden cardiac death in the young. Read More

Heart Rhythm O2 2020 Dec 28;1(5):326-335. Epub 2020 Oct 28.

Academic Medical Center, Amsterdam, Netherlands.

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an alternative to conventional transvenous ICD (TV-ICD) therapy to reduce lead complications.

Objective: To evaluate outcomes in channelopathy vs patients with structural heart disease in the EFFORTLESS-SICD Registry and with a previously reported TV-ICD meta-analysis in channnelopathies.

Methods: The EFFORTLESS registry includes 199 patients with channelopathies (Brugada syndrome 83, long QT syndrome 24, idiopathic ventricular fibrillation 78, others 14) and 786 patients with structural heart disease. Read More

Sci Rep 2021 Jun 10;11(1):12253. Epub 2021 Jun 10.

Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.

Loss-of-function (LoF) mutations in KCNQ1, encoding the voltage-gated K channel K7.1, lead to long QT syndrome 1 (LQT1). LQT1 patients also present with post-prandial hyperinsulinemia and hypoglycaemia. Read More

Methodist Debakey Cardiovasc J 2021 Apr 25;17(1):65-67. Epub 2021 Mar 25.

Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Texas.

Loperamide, a μ-opioid receptor agonist, can cause cardiotoxicity by inhibiting the potassium ion channel and slowing cardiomyocyte repolarization. This, in turn, can lead to frequent early afterdepolarizations, the most common mechanism of drug-induced long QT syndrome and torsades de pointes. Apical hypertrophic cardiomyopathy (AHCM) is a nonobstructive hypertrophic cardiomyopathy rarely associated with malignant arrhythmias. Read More

Methodist Debakey Cardiovasc J 2021 Apr 25;17(1):24-35. Epub 2021 Mar 25.

Houston Methodist Hospital, Houston, Texas.

Ventricular arrhythmias are potentially life-threatening disorders that are commonly treated with medications, catheter ablation and implantable cardioverter defibrillator (ICD). Adult patients who continue to be symptomatic, with frequent ventricular arrhythmia cardiac events or defibrillation from ICD despite medical treatment, are a challenging subgroup to manage. Surgical cardiac sympathetic denervation has emerged as a possible treatment option for people refractory to less invasive medical options. Read More

Sci Rep 2021 Jun 7;11(1):11909. Epub 2021 Jun 7.

Department of Pediatric Cardiology, Saitama Medical University International Medical Center, Hidaka, Japan.

The characteristic shape of the T-wave in congenital long-QT syndrome type 3 (LQTS3) is considered a late-onset T-wave. We analyzed the difference in the shapes of the T-waves of V5 in the electrocardiograms (ECGs) of LQTS3 cases and normal subjects using generalized Procrustes analysis. The J and Q points of LQTS3 cases are shifted to the upper left compared to those of normal subjects. Read More

Am J Case Rep 2021 Jun 3;22:e930568. Epub 2021 Jun 3.

Department of Intensive Care Medicine, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan.

BACKGROUND Refeeding syndrome is a complex metabolic disorder that develops following rapid nutritional administration after a long period of undernutrition. The onset mechanism involves intracellular transport of phosphorus, potassium, and water, in association with rapid glucose administration. The resulting hypophosphatemia is extremely dangerous and can cause severe heart failure and fatal arrhythmia. Read More

BMJ Paediatr Open 2021 18;5(1):e001026. Epub 2021 May 18.

Pediatrics and Neonatology Unit, Maternal-Child Department, Sapienza University of Rome, Santa Maria Goretti Hospital, Latina, Italy.

Objective: To evaluate the best timing for ECG screening in order to diagnose long QT syndrome and lower, at the same time, the false positives.

Design: We retrospectively evaluated the corrected QT (QTc) interval in the clinical reports of the ECG screening performed, as per internal protocol.

Setting: An outpatient setting in our Unit of Neonatology and Pediatrics, Santa Maria Goretti Hospital in Latina, Italy. Read More

JAMA Cardiol 2021 Jun 2. Epub 2021 Jun 2.

CVPath Institute, Gaithersburg, Maryland.

Importance: Unexplained sudden cardiac death (SCD) describes SCD with no cause identified. Genetic testing helps to diagnose inherited cardiac diseases in unexplained SCD; however, the associations between pathogenic or likely pathogenic (P/LP) variants of inherited cardiomyopathies (CMs) and arrhythmia syndromes and the risk of unexplained SCD in both White and African American adults living the United States has never been systematically examined.

Objective: To investigate cases of unexplained SCD to determine the frequency of P/LP genetic variants of inherited CMs and arrhythmia syndromes. Read More

Children (Basel) 2021 May 20;8(5). Epub 2021 May 20.

Division of Neonatology, Department of Pediatrics and Adolescent Medicine, Medical University of Graz, 8036 Graz, Austria.

An asphyxiated term neonate required postnatal resuscitation. After six minutes of cardio-pulmonary resuscitation (CPR) and two doses of epinephrine, spontaneous circulation returned, but was shortly followed by ventricular fibrillation. CPR and administration of magnesium, calcium gluconate, and sodium bicarbonate did not improve the neonate's condition. Read More

Bioorg Med Chem Lett 2021 May 29;46:128162. Epub 2021 May 29.

Human BioMolecular Research Institute, 6351 Nancy Ridge Dr. Suite B, San Diego, CA 92121, USA. Electronic address:

In the United States, approximately one million individuals are hospitalized every year for arrhythmias, making arrhythmias one of the top causes of healthcare expenditures. Mexiletine is currently used as an antiarrhythmic drug but has limitations. The purpose of this work was to use normal and Long QT syndrome Type 3 (LQTS3) patient-derived human induced pluripotent stem cell (iPSC)-derived cardiomyocytes to identify an analog of mexiletine with superior drug-like properties. Read More

Stem Cell Res 2021 May 20;54:102402. Epub 2021 May 20.

Stanford Cardiovascular Institute, United States; Depart of Medicine, Division of Cardiovascular Medicine, United States; Department of Radiology, Stanford University School of Medicine, United States. Electronic address:

Congenital long QT syndrome type 2 (LQT2) results from KCNH2 mutations that cause loss of Kv11.1 channel function which can lead to arrhythmias, syncope, and sudden death. Here, we generated three human-induced pluripotent stem cell (iPSC) lines from peripheral blood mononuclear cells (PBMCs) of two LQT2 patients carrying pathogenic variants (c. Read More

Am J Emerg Med 2021 May 21;49:24-28. Epub 2021 May 21.

Department of Critical Care, The 2nd Affiliated Hospital of Harbin Medical University, Harbin, China. Electronic address:

Background: To recognize and validate the predictor of risk factors for ICU patients with QTc intervals ≥500 ms.

Methods: We retrospectively reviewed 160 ICU patients with their medical electronic records including all demographic data, diagnosis measurements, ECGs and medication from March 1, 2018 to December 1, 2018. All information of patients' baseline, comorbidities, electrolytes and Long QT syndrome (LQTS)-inducing medications of patients with QT interval corrected (QTc) ≥ 500 ms (n = 80) and <500 ms (n = 80) were collected and analyzed using univariate and multivariate analyses to find predictors. Read More

Cardiol J 2021 ;28(3):358-359

Division of Cardiology, Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Foothills Medical Center, Calgary, Alberta, Canada.

Bioorg Med Chem Lett 2021 May 24;45:128133. Epub 2021 May 24.

Xenon Pharmaceuticals Inc., 200-3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada.

We describe the synthesis and biological evaluation of a series of novel aryl sulfonamides that exhibit potent inhibition of Na1.5. Unlike local anesthetics that are currently used for treatment of Long QT Syndrome 3 (LQT-3), the most potent compound (-)-6 in this series shows high selectivity over hERG and other cardiac ion channels and has a low brain to plasma ratio to minimize CNS side effects. Read More

Heart 2021 May 26. Epub 2021 May 26.

Heart Centre, Department of Cardiology, Amsterdam Universitair Medische Centra, Amsterdam, The Netherlands.

Congenital long QT syndrome (LQTS) is characterised by heart rate corrected QT interval prolongation and life-threatening arrhythmias, leading to syncope and sudden death. Variations in genes encoding for cardiac ion channels, accessory ion channel subunits or proteins modulating the function of the ion channel have been identified as disease-causing mutations in up to 75% of all LQTS cases. Based on the underlying genetic defect, LQTS has been subdivided into different subtypes. Read More

Eur J Hum Genet 2021 May 24. Epub 2021 May 24.

Department of Legal Medicine, University Hospital Frankfurt, Frankfurt am Main, Germany.

Proc Natl Acad Sci U S A 2021 May;118(21)

Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218;

In cardiomyocytes, Na1.5 channels mediate initiation and fast propagation of action potentials. The Ca-binding protein calmodulin (CaM) serves as a de facto subunit of Na1. Read More

J Am Coll Cardiol 2021 May;77(20):2573-2591

Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, Kensington, New South Wales, Australia; Cardiology Department, St Vincent's Hospital, Sydney, New South Wales, Australia; Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA. Electronic address:

In the initial 3 papers in this Focus Seminar series, the fundamentals and key concepts of precision medicine were reviewed, followed by a focus on precision medicine in the context of vascular disease and cardiomyopathy. For the remaining 2 papers, we focus on precision medicine in the context of arrhythmias. Specifically, in this fourth paper we focus on long QT syndrome, Brugada syndrome, and atrial fibrillation. Read More

Sud Med Ekspert 2021 ;64(3):59-63

Bashkir State Medical University, Ufa, Russia.

The review of the world literature on the most common causes, mechanism of development and diagnostic signs of sudden autopsy-negative cardiac death is presented. Two groups of reasons for the development of this pathology were identified - traumatic and non-traumatic. The traumatic group includes the cardio-inhibitory reflex and the trigemino-cardiac reflex. Read More

Eur Heart J Case Rep 2021 May 12;5(5):ytab166. Epub 2021 May 12.

Clinic for Electrophysiology, Herz- und Diabeteszentrum NRW, Ruhr-Universität Bochum, Georgstr. 11, 32545, Bad Oeynhausen, Germany.

Background: DiGeorge syndrome, also known as 'CATCH 22', is the most common deletion in humans and is one of the velocardiofacial syndromes. It is characterized by a specific facial phenotype, and structural and functional abnormalities in the cardiac and endocrine systems. One form of endocrine system dysfunction is hypocalcaemia, which causes arrhythmic events and can result in a transient loss of consciousness. Read More

Europace 2021 May 2. Epub 2021 May 2.

Université de Nantes, CNRS, INSERM, l'institut du thorax, Nantes F-44000, France.

Aims: Coronavirus disease of 2019 (COVID-19) has rapidly become a worldwide pandemic. Many clinical trials have been initiated to fight the disease. Among those, hydroxychloroquine and azithromycin had initially been suggested to improve clinical outcomes. Read More

Circ Genom Precis Med 2021 May 18. Epub 2021 May 18.

Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN.

- Prior epidemiological studies demonstrated that the p.D85N-KCNE1 common variant reduces repolarization reserve and predisposes to drug-induced QT prolongation/torsades de pointes. We sought to develop a cellular model for drug-induced long QT syndrome (DI-LQTS) using a patient-specific induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM). Read More

J Card Surg 2021 May 18. Epub 2021 May 18.

Department of Pediatric Cardiology, Hacettepe University Faculty of Medicine, Ankara, Turkey.

Introduction: Cardiac sympathetic denervation (CSD) is an effective procedure for the treatment of inherited channelopathies. Left CSD has traditionally been recommended as neuromodulation to prevent arrhythmia episodes; however, it is thought that bilateral sympathectomy in combination with Kuntz ablation may have additional effects effective due to the anatomical variability of preganglionic sympathetic fibers. The aim of the study was to share our single-center clinical experience with bilateral thoracoscopic sympathectomy for cardiac denervation in different groups of pediatric patients with malignant arrhythmias. Read More

An Pediatr (Engl Ed) 2021 Apr 20. Epub 2021 Apr 20.

Servicio de Cardiología Pediátrica, Hospital Universitario Vall d'Hebron, Barcelona, Paediatric Cardiology Department, Royal Brompton and Harefield NHS Foundation Trust, Londres, Spain.

Introduction: Many antiviral agents, such as hydroxychloroquine, have been used to treat COVID-19, without being broadly accepted. QTc prolongation is a worrisome adverse effect, scarcely studied in pediatrics.

Patients And Methods: Paediatric patients affected from COVID-19 who received antivirals were matched (1:2) with controls not infected nor exposed. Read More

Front Pharmacol 2021 30;12:651720. Epub 2021 Apr 30.

Arrhythmology and Electrophysiology Department, IRCCS Policlinico San Donato, Milan, Italy.

Adverse drug reactions (ADRs) are an important and frequent cause of morbidity and mortality. ADR can be related to a variety of drugs, including anticonvulsants, anaesthetics, antibiotics, antiretroviral, anticancer, and antiarrhythmics, and can involve every organ or apparatus. The causes of ADRs are still poorly understood due to their clinical heterogeneity and complexity. Read More

Front Pediatr 2021 27;9:634655. Epub 2021 Apr 27.

Al Jalila Children's Speciality Hospital, Dubai, United Arab Emirates.

Long QT syndactyly syndrome (long QT syndrome type 8), also known as Timothy Syndrome (TS) was first described in 1994 with still <50 case reported in the literature. The full spectrum of the syndrome is not yet known. Here we report a girl who presented with new onset refractory seizures and an undiagnosed cause of intermittent abdominal distention. Read More

J Pharm Pract 2021 May 13:8971900211015053. Epub 2021 May 13.

Department of Pharmacy Practice and Administration, Ernest Mario School of Pharmacy at Rutgers, The State University of New Jersey, New Brunswick, NJ, USA.

Managing the risks and consequences of long QT syndrome can be challenging. Multiple factors contribute to the prolongation of the heart-rate corrected QT (QTc) interval including many drug-drug and drug-disease state interactions. Current literature is often focused on avoiding dysrhythmias with limited guidance on acute management strategies. Read More

Arthritis Rheumatol 2021 May 10. Epub 2021 May 10.

Veterans Affairs Medical Center, Washington, DC, USA.

Objective: Hydroxychloroquine (HCQ) may prolong the QT interval, a risk factor for torsade de pointes, a potentially fatal ventricular arrhythmia. We examined the cardiovascular safety of HCQ in patients with rheumatoid arthritis (RA).

Methods: We conducted an active comparator safety study of HCQ in a propensity score-matched cohort of 8852 Veterans newly diagnosed with RA between October 1, 2001, and December 31, 2017. Read More