Cardiac, Arrhythmia – ABC CARDIOL

ABC

Editorial

Applicability of Machine Learning Algorithms in the Diagnosis of Arrhythmias – How Long Until The Machine Starts Teaching Us?

The electrocardiogram (ECG), in clinical use since the early 1900s, remains a beloved tool for cardiologists, clinicians, and medical students. It is arguably the most important bedside instrument in cardiology, essential for managing arrhythmias and acute ischemic syndromes, as well as guiding electrophysiologic care. Still, advances in electrocardiography interpretation have been only modest in the last hundred years. Devices have become more portable, digital, and capable of longer recordings, but core interpretive principles remain rooted in early 20th-century methods. In recent years, this has been reshaped by the rise of computational technologies, especially artificial intelligence (AI). Tools such as deep neural networks (DNNs) and machine learning models (MLMs) are enabling a new era in ECG analysis, the AI-enhanced electrocardiography (AI-enhanced ECG).

In this issue of the ABC Cardiol, Guimarães do Nascimento et al. report on a systematic review of studies evaluating the applicability of AI-enhanced ECG in the diagnosis of cardiac arrhythmias. They included studies of different methodologies that addressed the role of AI-enhanced ECG in the detection of long-QT syndrome (LQTS) (one study), corrected QT interval (cQTi) (one study), and atrial fibrillation (AF) (eleven studies).

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IJCS

Editorial

Adding the Exercise Test as a Tool in the Medical Decision-Making Process in Brugada Syndrome

Luiz Eduardo Mastrocola et al. Fábio Mastrocola

Introduction

Most cases of sudden cardiac arrest (SCA) and sudden cardiac death (SCD) are caused by ventricular tachyarrhythmias, with most of these associated with structural heart disease, particularly coronary heart disease. SCA is an uncommon occurrence in the apparently normal heart and accounts for only 5 to 10 percent of total cases.

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ABC

Case Report

Life-Threatening Ventricular Arrhythmia Induced by Atrial Tachycardia in a Child with an SCN5A Mutation

Márcio Augusto Silva et al. Jorge Elias Neto Guilherme Muller de Campos Futuro Erick Sessa Merçon … Deborah Vasconcelos Ricardo Kuniyoshi

Introduction

Mutations in the SCN5A gene, encoding the cardiac Na+channel, can result in several life-threatening arrhythmias. These mutations have proven to be causative for inherited and primarily electrical diseases, including Brugada Syndrome (BrS), Long QT Syndrome, and other cardiac conduction disturbances.^, BrS, the most reported condition in this group of disorders, has typically been described in adult populations and related to approximately 20% of all sudden deaths (SD) in patients with apparently normal hearts.^– Therefore, few reports have shown significant arrhythmic events (AE) caused by this mutation in childhood.

Atrial arrhythmias, as well as sick sinus syndrome (SSS), may be related to Na+channel abnormalities. In BrS, atrial arrhythmias are being diagnosed in up to 38% of patients and are related to worse prognosis.

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ABC

Artigo Original

Effects of stimulation with pulsatile continuous electrical current on atrial electrophysiological properties: experimental study of atrial fibrillation in dogs

Dalmo Antonio Ribeiro Moreira et al. Amanda Guerra Moraes Rego Sousa Paulo Valente Elizabete Hosri Leone

OBJECTIVE: To assess whether atrial stimulation with pulsatile continuous electrical current induces atrial fibrillation and to evaluate its effects on atrial electrophysiological properties as well as the atrial histological alterations. METHODS: Twenty-two dogs underwent right lateral thoracotomy and implantation of pacemaker electrodes in the sulcus terminalis (ST), in the right atrial appendix (RAb), and in the posteroinferior region of the left atrium (LA). A pair of electrodes was sutured to the right atrial appendix for stimulation with a 9-volt alkaline battery connected to a system (LM 555) that transforms the linear continuous energy of the battery into a pulsatile continuous current for 60 minutes. Atrial epicardial biopsy was performed before and after atrial stimulation. RESULTS: No differences were observed in the durations of the effective atrial refractory periods. The times of intra-atrial and interatrial conduction, as well as that of atrial extrastimuli, were prolonged. The duration of atrial electrograms was prolonged during sinus rhythm and programmed atrial stimulation; in 68% of the dogs, atrial fibrillation was induced and was sustained. Interstitial edema and bands of cellular contraction were observed in the subepicardium on optical microscopy, as were intense myofibrillar disorganization and an increase in the size of the mitochondria on electron microscopy. CONCLUSION: That technique of atrial stimulation induces atrial fibrillation and causes atrial changes that increase atrial vulnerability to the appearance of atrial fibrillation.

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ABC

Artigo Original

Isolation of the pulmonary veins in patients with permanent atrial fibrillation secondary to mitral valve disease

Gustavo G. Lima et al. Renato A.K. Kalil Tiago L.L. Leiria Gustavo F. Vanni … Marcelo H. Miglioransa Daniel L. Faria-Corrêa Domingos Hatem Rogério Abrahão João R. Sant'Anna Paulo Prates Ivo A. Nesralla

OBJECTIVE: To assess the efficacy of surgical isolation of the pulmonary veins for re-establishing sinus rhythm in patients with atrial fibrillation secondary to mitral valve disease. METHODS: Thirty-three (67% were women) patients with permanent atrial fibrillation and indication for surgical correction of the mitral valve underwent surgical isolation of the pulmonary veins. Their mean age was 56.3±10 years, preoperative NYHA functional class was 3.2±0.6, left atrial size was 5.5±0.9 cm, and ejection fraction was 61.3±13%. The surgical technique consisted of a circumferential incision surrounding the 4 pulmonary veins, excision of the left atrial appendage, and a perpendicular incision originating in the inferior margin of the circumferential incision isolating the pulmonary veins down to the mitral valve. Early arrhythmias were aggressively treated with cardioversion. RESULTS: The mean follow-up was 23.9±17 months, and 3 patients died in the postoperative period. Ten patients required electrical cardioversion in the postoperative period; 87% had sinus rhythm in the last medical visit, and 33% were using amiodarone. CONCLUSION: Isolation of the pulmonary veins associated with mitral valve surgery is an effective and safe technique for maintaining sinus rhythm in patients with permanent atrial fibrillation.

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Applicability of Machine Learning Algorithms in the Diagnosis of Arrhythmias – How Long Until The Machine Starts Teaching Us?

Adding the Exercise Test as a Tool in the Medical Decision-Making Process in Brugada Syndrome

Introduction

Life-Threatening Ventricular Arrhythmia Induced by Atrial Tachycardia in a Child with an SCN5A Mutation

Introduction

Effects of stimulation with pulsatile continuous electrical current on atrial electrophysiological properties: experimental study of atrial fibrillation in dogs

Isolation of the pulmonary veins in patients with permanent atrial fibrillation secondary to mitral valve disease

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