Cardiac Arrhythmias – ABC CARDIOL

IJCS

Original Article

QT Prolongation Following Premature Ventricular Contractions: A Potential Marker of Concealed Long QT Syndrome

Khatuna Jalabadze et al. Pavle Machavariani Bachuki Tsiklauri Natalia Garuchava … Ia Avaliani Maya Chigogidze

Abstract

Background:

Long QT syndrome (LQTS) predisposes individuals to malignant ventricular arrhythmias and sudden cardiac death; however, diagnosis remains challenging in patients with borderline corrected QT (QTc) values. Premature Ventricular Contractions (PVCs) may unmask concealed abnormalities of ventricular repolarization.

Aim:

To determine whether post-PVC QTc prolongation can differentiate patients with confirmed LQTS, healthy controls, and borderline index cases.

Methods:

In this retrospective study, 24-hour electrocardiography (ECG) recordings from 84 subjects were analyzed, including 10 patients with confirmed LQTS, 72 healthy controls, and 2 index patients with borderline baseline QTc values. QTc intervals before and after PVCs were measured manually and corrected using Bazett’s formula. Between-group differences were evaluated using analysis of covariance (ANCOVA) adjusted for baseline QTc, whereas within-group changes were assessed with paired t-tests. A two-tailed p < 0.05 was considered statistically significant.

Results:

Post-PVC QTc intervals were longer in patients with LQTS than in healthy controls (488 ± 23 ms vs 391 ± 37 ms; adjusted p = 0.066). Overall, PVCs were associated with a mean QTc increase of +15.7 ms (95% CI 7.1–24.3; p = 0.0005), with larger increases observed in LQTS patients (+22.3 ms; p = 0.0019) compared with healthy controls (+10.0 ms; p = 0.0098). The two index patients exhibited marked QTc prolongation, rising from borderline baseline values (360–460 ms) to 540–600 ms (Δ≈165 ms).

Conclusion:

PVC-induced QTc prolongation may help distinguish healthy individuals from patients with overt or borderline LQTS. Whereas healthy controls demonstrated mild physiologic adaptation, patients with confirmed LQTS showed consistent QTc prolongation, and index patients exhibited marked post-PVC increases suggestive of concealed repolarization abnormalities. Assessment of QTc following PVCs may represent a simple bedside approach to improve diagnostic accuracy and risk stratification in LQTS; prospective studies in larger cohorts are warranted to confirm these findings.

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Original Article

Electrocardiographic Analysis of Ventricular Repolarization in Patients With Psoriasis: A Cross-Sectional Study

Guilia Bevilacqua Schmitz et al. Raíssa Massaia Londero Chemello Marco Lumertz Saffi Luciane Prado de Vargas Diego Chemello

Abstract

Background

Psoriasis is a chronic inflammatory disease. Cardiovascular diseases, including arrhythmias, tend to occur more frequently in these patients.

Objective

This study aimed to investigate new electrocardiographic markers for assessing ventricular repolarization in outpatients with psoriasis in a tertiary center in Brazil.

Methods

This work is a cross-sectional study, which selected outpatients with psoriasis undergoing follow-up in a tertiary dermatology service in southern Brazil. The controls were selected from a private outpatient clinic. All the electrocardiogram (ECG) analyses were performed by one certified electrophysiologist. Comparative statistical tests and Spearman’s correlation analysis were used. Measures with statistically significant differences in the univariate analysis were taken to the multivariate analysis (Generalized Linear Model – Poisson Regression with age adjustment). A P<0.05 value was considered statistically significant for all analyses.

Results

A total of 130 individuals were evaluated, mean age of 53.1±15.1 years. The univariate analysis showed no difference in Corrected QT interval (QTc) between the groups, considering 411.2±21.2 ms in the psoriasis group (PG) versus 412.8±25.2 ms in the control group (CG) (p = 0.694). The median values of Corrected QT dispersion (QTdisc) were lower in the PG as compared to the CG, 15.7 ms (IQR 11.5–24.2 ms) versus 39.8 ms (Interquartile Range, IQR, 32.8–46.6 ms), respectively (p<0.001). For peak-to-end interval of the T wave (Tp-e) and Tp-e/QTc values, the mean values were also lower in patients with psoriasis. For Tp-e, the mean values in the PG were 91.7±11.6 ms versus 96.0±9.2 ms in the CG (p = 0.024). For The Tp-e/QTc, the mean values in the PG were 0.22±0.03 versus 0.23±0.03 in the CG (p = 0.024). The multivariate analysis, adjusted for age, QTdis, Qtdisc, Tp-e, and Tp-e/QTc, remained independently lower in patients with psoriasis.

Conclusion

The evaluation of ventricular repolarization parameters in a sample of outpatients with psoriasis in southern Brazil showed that ventricular repolarization values were generally lower when compared to controls. No significant correlation was found between disease activity and ventricular repolarization parameters.

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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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IJCS

Review Article

Syncope and Rhythm Disturbances as Common Clinical Manifestations in Amyloidosis

Nágela S. V. Nunes et al. Erivelton Nascimento Ronaldo Altenburg Gismondi Erito Marques de Souza Filho

Abstract

Amyloidosis results from deposition of insoluble fibrillar protein compounds in various organs, including the heart. Cardiac involvement occurs in both atria and ventricles, leading to restrictive cardiomyopathy, heart failure (HF), and arrhythmias. Five amyloid proteins affect cardiac tissue: light and heavy chain forms of immunoglobulin, transthyretin (TTR), apolipoprotein 1, and amyloid A. Approximately 95% of cardiac involvement stems from light chain of immunoglobulin and TTR deposition in heart. Chamber stiffness and rhythm disturbances occur in cardiac amyloidosis (CA), encompassing from HF to atrial and ventricular arrhythmias (VA), and both can compromise each other. It is known that conduction system disorders and VA increase sudden death risk, as amyloid infiltration, inflammation, and fibrosis alter myocardial electrophysiology. Beyond the heart, autonomous nerve systems suffer amyloid deposition, contributing to syncope manifestation and increasing the risk of death and poor prognosis. In this context, our review sheds light on the importance of recognizing syncope and rhythm disturbances as crucial markers in the early identification and management of CA, potentially offering avenues for prompt intervention and improved patient outcomes.

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Editorial

Lessons Learned from Cardiac Complications of COVID-19 and the Value of the Electrocardiogram

Javier César Barcos et al. Ana G. Múnera Echeverri Adrian Baranchuk

Since the declaration of the coronavirus disease 2019 (COVID-19) pandemic in March 2020, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, much has been learned about the epidemiology, pathophysiology, clinical characteristics, and predictors of poor prognosis. Furthermore, cardiovascular implications have emerged as significant contributors to morbi-mortality. In this sense, the recently published work of Galindes-Casanova et al. reinforces existing evidence on acute COVID-19 infection, cardiac complications, and electrocardiogram (ECG) manifestations.

By the end of 2023, COVID-19 had already caused more than 770 million confirmed cases and 7 million deaths worldwide. The disease is characterized by an acute phase that lasts up to 4 weeks. Symptoms and complications could occasionally extend up to several months, called post-acute COVID-19. The main clinical manifestations are fever and respiratory symptoms. Less commonly, extrapulmonary involvement can also occur, involving different organs and systems secondary to direct and indirect viral damage, the latter through the dysregulation of the immune system, a hyperinflammatory state, endothelial dysfunction, coagulopathy, a prothrombotic state, and an imbalance of the renin-angiotensin-aldosterone system. These complex mechanisms, added to the injury of different organs and the adverse effects of COVID-19 treatments, favor the development of cardiac complications ().

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Original Article

Evaluation of Symptomatic and Asymptomatic Outpatients in the Post-COVID-19 Period With Electrocardiographic Ventricular Depolarization and Repolarization Parameters

Muammer Karakayalı et al. Inanc Artac Dogan Ilis Timor Omar … Mehmet Altunova Ezgi Guzel İbrahim Rencüzoğulları Yavuz Karabağ

Abstract

Background

A recently identified viral illness called coronavirus disease 2019 (COVID-19) is spreading quickly. Numerous cardiovascular issues such as arrhythmias and electrocardiogram (ECG) alterations have been linked to COVID-19.

Objective

In this investigation, we compared ECG indicators of depolarization and repolarization heterogeneity between symptomatic individuals who complained of palpitations and chest discomfort following COVID-19 and those who did not.

Methods

In this prospective case-control study, 56 post-COVID-19 patients who did not have any symptoms of chest discomfort or palpitations were included in the control group and compared with a study group comprising 73 post-COVID-19 patients who presented at the outpatient clinic with complaints of chest pain and palpitation. Electrocardiographic (ECG) measures were used to assess depolarization and repolarization of the ventricles. These measures included the Tpeak-Tend (Tp-e) interval, QT dispersion (QTd), Tp-e/QT ratio, Tp-e/QTc ratio, frontal QRS-T (fQRS-T) angle, and fragmented QRS (FQRS). Two cardiologists recorded the patients’ ECG data. A statistically significant result was defined as a p value less than 0.05.

Results

The results of multivariate analysis including FQRS, Tp-e interval, Tp-e/QT, and Tp-e/cQT showed that presence of FQRS (OR: 6.707, 95% CI: 1.733-25.952; p = 0.006) was an independent predictor of symptomatic post-COVID -19 patients.

Conclusion

In our study, FQRS was found to be significantly higher in symptomatic post-COVID-19 patients than in non-symptomatic post-COVID-19 patients, while Tp-e interval was found to be lower.

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Editorial

Safety of Dental Anesthesia in ICD Recipients

Ricardo Alkmim Teixeira

Some anesthetic agents administered during general anesthesia can cause heart rhythm disorders, mainly associated with autonomic imbalance. Off-target cardiac sodium channel blockade is considered the canonical mechanism behind cardiotoxicity.

Lidocaine, the most common local anesthetic, produces a transient loss of sensory, motor, and autonomic function when the drug is injected or applied close to neural tissues; furthermore, it has a good safety margin before reaching toxic blood levels. However, care must be taken to keep track of the total dose given to minimize its systemic toxicity. In addition to direct nerve toxicity, systemic toxicity affecting the brain and/or cardiac muscle can also occur. Cardiovascular toxicity usually appears as tachycardia and hypertension; however, with increasing toxicity, bradycardia and hypotension can occur. Ventricular arrhythmias and cardiac arrest also have been described. Because of its potential effects upon the heart, it is also commonly used as an antiarrhythmic agent to depress ventricular arrhythmias in controlled doses.

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Review Article

Cardiac Arrhythmias and Covid-19

Alexsandro Alves Fagundes et al. Sissy Lara de Melo Luciana Armaganijan Ricardo Kuniyoshi … Luis Gustavo Belo de Moraes Vanessa Alves Guimarães Borges Mauricio Scanavacca Martino Martinelli Filho Ricardo Alkmim Teixeira

Abstract

Cardiovascular manifestations of COVID-19 include cardiac rhythm disturbances, whose mechanisms, incidence, and most common types are not well established in this population. Intense inflammatory response and metabolic activity contribute to recurrence of pre-existing arrhythmias, and other arrhythmias can occur due to myocardial injury, acute coronary insufficiency, and electrolyte disturbances. Brady- and tachyarrhythmias, as well as conduction disorders have been described. QT interval prolongation and fatal ventricular arrhythmias ( Torsades de Pointes ) may result from the pathological process or adverse effect of drugs (antiarrhythmics, chloroquine / hydroxychloroquine, azithromycin and antivirals). Patients with congenital heart disease and hemodynamic repercussions, patients with signs of heart failure, pulmonary hypertension, cyanosis, hypoxemia, and those who underwent heart transplantation and immunosuppression are at greater risk. In patients with implantable cardioverter-defibrillators (ICDs), the risk depends on the presence of structural heart disease. In the course of COVID-19, in-person assessment of these patients should be limited to high-risk situations, including syncope, worsening of heart failure and shock delivery by ICDs. Likewise, cardiac implantable electronic device implantation or replacement surgery should be limited to emergency and urgent cases, including symptomatic high-degree atrioventricular block, ICD for secondary prevention and pulse generator replacement due to battery drain.

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Editorial

Intracardiac Conduction Intervals: An Electrophysiological Mirror of the Brazilian Population

Erivelton A. do Nascimento

In the current edition of the International Journal of Cardiovascular Sciences, Leiria et al. have published a historical cohort of 124 electrophysiological studies considered normal, and evaluated three parameters of intracardiac conduction: (1) PA interval; (2) AH interval and (3) HV interval. The reference values for baseline electrophysiological parameters in the Brazilian population are of great interest due to their unique characteristics.

Since the description of the electrical potential in the end portion of the atrioventricular (AV) node by, Dandamudi and Vijayaraman related Wilhelm His Jr., in 1893, which would come to be named the bundle of His, cardiac electrophysiology has added knowledge to both the diagnosis and treatment of the different forms cardiac arrhythmias, and to the field of artificial cardiac stimulation.

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