Torsades de Pointes – ABC CARDIOL

IJCS

Case Report

Mexiletine in The Treatment of Long QT Syndrome Type 2 in Infants: A Case Report

Jessica Laureano Martins et al. Nicole Sarmento Queiroga Fernanda Calumby Nóbrega Guimarães Guilherme Augusto Teodoro Athayde … Halbiege Léa Silva Quirino da Silva Rogério Braga Andalaft

Introduction

Congenital Long QT Syndrome (LQTS) is one of the main causes of sudden cardiac death (SCD) in the pediatric age group, with a prevalence of approximately one case for every 2,000 newborns. The most prevalent inheritance is dominant, with the typical phenotype associated with cardiac manifestations.

The genetic alteration of LQTS is multigenic, with 17 main genes, and in 80% of the cases, it identifies: KCNQ1 (LQTL1), KCNH2 (LQTL2), and SCN5A (LQTL3). The LQTS type 2 (LQTS2) subtype alters the expression of potassium channels in myocytes, causing electrical instability and ventricular arrhythmias. The most common arrhythmia is Torsades de Pointes (TdP), a type of polymorphic ventricular tachycardia, which can lead to syncope, seizures, and sudden death.

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ABC

Research Letter

Mexiletine in a Newborn with Type 3 Long QT Syndrome: When Access is Difficult

Eduardo Nolla Silva Pereira et al. Luciana Sacilotto Gabrielle D’Arezzo Pessente Cinthya Guirao … Mariana Lombardi Peres de Carvalho Alexandre da Costa Pereira Francisco Carlos da Costa Darrieux Maurício Ibrahim Scanavacca

Introduction

Long QT syndrome type 3 (LQT3) is a highly lethal channelopathy. It is associated with delayed closing of sodium channels, resulting from mutations in the SCN5A gene, with an autosomal dominant pattern, responsible for 7-10% of all long QT syndromes (LQTSs). The initial presentation can have a wide spectrum, from asymptomatic to sudden death in the first year of life. The addition of class IB sodium channel blocker (mexiletine) to propranolol or nadolol is considered a gene-guided treatment, as its benefit is proven in LQT3. In some countries, such as Brazil, it is not feasible to treat patients with LQT3, because of the unavailability of mexiletine.

We present here a severe case of a child with LQT3, who underwent multiple implantable cardioverter-defibrillator (ICD) therapies because of difficult access to mexiletine in Brazil.

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ABC

Case Report

Drug-Induced Long-QT and Torsades de Pointes in Elderly Polymedicated Patients

Daniel García-Fuertes et al. Elena Villanueva-Fernández Manuel Crespín-Crespín

Introduction

Polymedication affects one in three patients older than 65 years. Its risks are widely known and are specially related to pharmacological interactions. One of these potential risks is the appearance of malignant ventricular arrhythmias when drugs that prolong QT interval are prescribed, including antibiotics, antidepressants, antiemetics, psychotropic medication or even antiarrhythmic drugs.^– The development of ventricular arrhythmias such asTorsades de Pointes (TdP), typically related to QT prolongation, is a potentially lethal complication. It is mandatory to recognize the drugs that can cause it, avoiding their joint use or planning a close monitoring in case their combination cannot be avoided.

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ABC

Case Report

Coronary Fistulas in a Patient with a Novel Long QT Syndrome Mutation

Rui Plácido et al. Nuno Cortez-Dias Arminda Veiga Cláudia Jorge … Gábriel Miltenberger-Miltény Fausto Pinto

Introduction

The congenital long QT syndrome (LQTS) is a genetic cardiac channelophathy with variable penetrance characterized by corrected QT (QTc) interval prolongation and predisposition to polymorphic ventricular tachycardia (PVT), which normally presents with syncope or sudden death. It can be caused by mutations in different ion channels, resulting in prolongation of the myocardial repolarization. The clinical course of LQTS throughout a patient’s lifetime is significantly influenced by the genotype and acquired factors that additionally compromise myocardial repolarization, including drug use, serum electrolyte abnormalities, autoimmune diseases, severe bradycardia, acute heart failure decompensation and myocardial ischemia.

This report presents the first description of PVT precipitated by myocardial ischemia secondary to multiple coronary fistulas in a patient with a novel LQTS-causing mutation.

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Letter to the Editor

An Issue Waiting to be Clarified: Effects of the QT Prolonging Drugs on Tp-e Interval

Omer Yiginer et al. Mehmet Dogan Emrah Erdal

We read the article ‘Impact of Psychotropic Drugs on QT Interval Dispersion in Adult Patients’ by Claudio et al. with great interest. They investigated in this study the effects of psychotropic drugs on QT interval (QTI), corrected QT interval (QTc), and QT dispersion (QTd). They concluded that psychotropic drugs increased QTd and QTc interval.

QTd is the most frequently used non-invasive method to quantify electrical myocardial heterogeneity. However, there are variable results in studies related to QTI due to the technical limitations in measurements. It is well-known that the reproducibility of QTI measurements is low both in manual and automatic measurements. In this study, the measurements were performed digitally by four cardiologists using the Preview software with a magnification of 300%. We appreciated the method used in this study in order to obtain more accurate data. It is recommended that measurements be done digitally at least by two cardiologists.

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Artigo Original

Impact of Psychotropic Drugs on QT Interval Dispersion in Adult Patients

Bruno de Queiroz Claudio et al. Marcelle Azevedo Nossar Costa Filipe Penna Mariana Teixeira Konder … Bruno Miguel Jorge Celoria Luciana Lopes de Souza Roberto Pozzan Roberta Siuffo Schneider Felipe Neves Albuquerque Denilson Campos Albuquerque

Background:

Drug-induced increase in QT dispersion has been associated with potentially fatal ventricular arrhythmias. Little is known about the use of psychotropic substances, alone or in combination with other drugs on QT dispersion.

Objectives:

To evaluate the impact of psychotropic drugs on QT interval dispersion in adults.

Methods:

An observational cohort study was designed involving 161 patients hospitalized from an emergency department at a tertiary hospital, divided into psychotropic users or non-users. Demographic, clinical, laboratory data and drugs used on a regular basis were collected on admission, in addition to 12-lead electrocardiogram with QT dispersion measurement.

Results:

QT dispersion was significantly higher in the psychotropic user group compared to non-users (69.25 ± 25.5 ms vs. 57.08 ± 23.4 ms; p = 0.002). The QT interval corrected by Bazzett formula was also higher in the psychotropic drugs user group, with statistical significance. (439.79 ± 31.14 ms vs. 427.71 ± 28.42 ms; p = 0.011). A regression analysis model showed a positive association between the number of psychotropic drugs used and QT interval dispersion, with r = 0.341 and p < 0.001.

Conclusions:

The use of psychotropic drugs was associated with increased QT dispersion and this increase was accentuated, as the number of psychotropic drugs used was higher.

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Mexiletine in The Treatment of Long QT Syndrome Type 2 in Infants: A Case Report

Introduction

Mexiletine in a Newborn with Type 3 Long QT Syndrome: When Access is Difficult

Introduction

Drug-Induced Long-QT and Torsades de Pointes in Elderly Polymedicated Patients

Introduction

Coronary Fistulas in a Patient with a Novel Long QT Syndrome Mutation

Introduction

An Issue Waiting to be Clarified: Effects of the QT Prolonging Drugs on Tp-e Interval

Impact of Psychotropic Drugs on QT Interval Dispersion in Adult Patients

Background:

Objectives:

Methods:

Results:

Conclusions:

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