Efficacy and safety of a novel temperature-controlled catheter for cavotricuspid isthmus ablation.

BACKGROUND: Maintaining an adequate temperature at the target site is essential for effective ablation. We hypothesized that a tissue temperature-controlled (T-Con) catheter for cavotricuspid isthmus (CTI) ablation could improve the procedural ablation parameters. PURPOSE: To evaluate the efficacy and safety of the T-Con (DiamondTemp™) catheter for CTI ablation compared with non-irrigation (Non-Irri) and irrigation (Irri) catheters. METHODS: We analyzed 150 patients who underwent prophylactic CTI ablation combined with pulmonary vein isolation. The Non-Irri, Irri, and T-Con catheter groups comprised 50 patients each, and the ablation procedural parameters and complications were compared between these groups. RESULTS: There were no significant differences in clinical background characteristics among the three groups. The Kruskal-Wallis and post hoc tests demonstrated that the T-Con group showed the lowest total radiofrequency energy delivery time among the three groups (median [25 and 75 percentiles]: 340 [209, 357], 147 [100, 199], and 83 [61, 109] s, respectively in the Non-Irri, Irri, and T-Con groups; T-Con versus Non-Irri, p < .01; T-Con versus Irri, p < .01). The total procedural time and acute reconnection rate in the T-Con group (264 s and 4%, respectively) were lower than those in the Non-Irri group (438 s and 24%) but were similar to those in the Irri group (268 s and 6%). No significant complications were observed in any group. CONCLUSIONS: The T-Con catheter achieved a short energy delivery time and a low acute reconnection rate, indicating its potential as an alternative catheter for CTI ablation.

Antiarrhythmic therapy for narrow QRS supraventricular tachyarrhythmias in newborns and infants in the first year of life: Potent tools to be handled with care.

Supraventricular tachyarrhythmias pose a significant challenge in neonates and infants, particularly within the first year of life, where prompt and effective management is crucial. By synthesizing available evidence and clinical experience, this review aims to provide a comprehensive overview of antiarrhythmic therapy in this vulnerable population, with a focus on narrow QRS supraventricular tachyarrhythmias. This review examines the current understanding of supraventricular tachyarrhythmia management and discusses the challenges associated with antiarrhythmic therapy in newborns and infants during the critical first year of life, evaluating the efficacy and safety of various antiarrhythmic agents commonly utilized in this population, including dosing considerations, adverse effects, and strategies for acute management and prophylactic long-term antiarrhythmic treatment.

A Case Report of an Acute Severe Tachyarrhythmia Presentation With Underlying Cardiomyopathy in a Patient With Anabolic Androgenic Steroid and Thyroxine Misuse.

A description of an acute hospital presentation with severe tachyarrhythmia requiring multiple direct current cardioversions in a 45-year-old male bodybuilder with underlying cardiomyopathy possibly caused by long-term anabolic steroid abuse and more recent thyroxine misuse is described. A review of the literature regarding the above associations was also done. This case report further adds to the literature regarding the harmful effect of androgenic anabolic steroid misuse (with the added effect of thyroxine misuse in this case) on the heart.

Wide Spectrum of Bradyarrhythmias and Supraventricular Tachyarrhythmias in Sportsmen: Run Forrest, Run?!

The intricate relationship between sports participation and cardiac arrhythmias is a key focus of cardiovascular research. Physical activity, integral to preventing atherosclerotic cardiovascular disease, induces structural, functional, and electrical changes in the heart, potentially triggering arrhythmias, particularly atrial fibrillation (AF). Despite the cardiovascular benefits, the optimal exercise amount remains unclear, revealing a J-shaped association between AF and exercise. Endurance athletes, particularly males, face elevated AF risks, influenced by age. Risk factors vary among sports modalities, with unique physiological responses in swim training potentially elevating AF risk. Clinical management of AF in athletes necessitates a delicate balance between rhythm control, rate control, and anticoagulation therapy. Sport-induced bradyarrhythmias, including sinus bradycardia and conduction disturbances, are prevalent among athletes. Managing bradycardia in athletes proves challenging due to its complex and not fully understood pathophysiology. Careful consideration is required, particularly in symptomatic cases, where pacemaker implantation may be necessary for sinus node dysfunction. Although pacing is recommended for specific atrioventricular (AV) blocks, milder forms often prevail without restricting sports participation. This review explores the nuanced relationship between exercise and tachy- and bradyarrhythmia in athletes, addressing the challenges clinicians face when optimizing patient care in this distinctive population.

Implantable Cardiac Devices in Patients with Brady- and Tachy-Arrhythmias: An Update of the Literature.

Implantable cardiac devices are a vital treatment option in the management of tachy/brady-arrhythmias and heart failure with conduction disease. In the recent years, these devices have become increasingly sophisticated, with high implantation success rates and longevity. However, these devices are not without risks and complications, which need to be carefully considered before implantation. In an era of rapidly evolving cardiac device therapies, this review article will provide an update on the literature and outline some of the emerging technologies that aim to maximise the efficiency of implantable devices and reduce complications. We discuss novel pacing techniques, including alternative pacing sites in anti-bradycardia and biventricular pacing, as well as the latest evidence surrounding leadless device technologies and patient selection for implantable device therapies.

Sex differences in achieving guideline-recommended heart rate control among a large sample of patients at risk for sudden cardiac arrest.

Background: Despite known clinical benefits, guideline-recommended heart rate (HR) control is not achieved for a significant proportion of patients with HF with reduced ejection fraction. The wearable cardioverter-defibrillator (WCD) provides continuous HR monitoring and alerts that could aid medication titration. Objective: This study sought to evaluate sex differences in achieving guideline-recommended HR control during a period of WCD use. Methods: Data from patients fitted with a WCD from 2015 to 2018 were obtained from the manufacturer's database (ZOLL). The proportion of patients with adequate nighttime resting HR control at the beginning of use (BOU) and at the end of use (EOU) were compared by sex. Adequate HR control was defined as having a nighttime median HR <70 beats/min. Results: A total of 21,440 women and a comparative sample of 17,328 men (median 90 [IQR 59-116] days of WCD wear) were included in the final dataset. Among patients who did not receive a shock, over half had insufficient HR control at BOU (59% of women, 53% of men). Although the proportion of patients with resting HR ≥70 beats/min improved by EOU, 43% of women and 36% of men did not achieve guideline-recommended HR control. Conclusion: A significant proportion of women and men did not achieve adequate HR control during a period of medical therapy optimization. Compared with men, a greater proportion of women receiving WCD shocks had insufficiently controlled HR in the week preceding ventricular tachyarrhythmia/ventricular fibrillation and 43% of nonshocked women, compared with 36% of men, did not reach adequate HR control during the study period. The WCD can be utilized as a remote monitoring tool to record HR and inform adequate uptitration of beta-blockers, with particular focus on reducing the treatment gap in women.

Digoxin and Risk of Ventricular Tachyarrhythmia and Death in ICD Recipients.

BACKGROUND: Some studies have shown digoxin use to be associated with adverse outcomes, including increased mortality. There are limited data on whether digoxin use is associated with increased risk of ventricular tachycardia/ventricular fibrillation (VT/VF) in heart failure patients with an implantable cardioverter-defibrillator (ICD). OBJECTIVES: This study sought to assess whether digoxin use is associated with increased risk of VT/VF in patients with heart failure with reduced ejection fraction with a primary prevention ICD in landmark clinical trials. METHODS: The study cohort consisted of patients with an ICD or cardiac resynchronization therapy-defibrillator who were enrolled in 4 landmark MADIT trials (Multicenter Automatic Defibrillator Implantation Trials). We employed propensity score quintile stratification for treatment with digoxin as well as additional multivariable adjustment to assess the risk of digoxin vs no-digoxin therapy for the endpoints of first and recurrent VT/VF and all-cause mortality. The proportional hazards regression models for arrhythmia-specific endpoints incorporated adjustments for the competing risk of death. RESULTS: At baseline, 1,155 of 4,499 patients were on digoxin (26%). After propensity score quintile stratification, patients prescribed digoxin were shown to exhibit a statistically significant 48% increased risk of VT/VF (P < 0.001), 42% increased risk of the composite of VT/VF or death (P < 0.001), and a 37% increased risk of all-cause mortality (P = 0.006). Digoxin use was also associated with increased risk of appropriate ICD shocks (HR: 1.91; P < 0.001) and with increased burden of VT/VF events (HR: 1.46; P = 0.001). CONCLUSIONS: Our findings suggests that digoxin use is associated with ventricular tachyarrhythmia and death in heart failure with reduced ejection fraction patients with an ICD.

Activation of PKC affects the ventricular restitution properties and arrhythmogenesis through L-type Ca+ current.

OBJECTIVE: To investigate the role of protein kinase C (PKC) in action potential duration (APD) restitution and ventricular tachyarrhythmias (VAs). METHODS AND RESULTS: Rabbits hearts were isolated and prepared for Langendorff perfusion technique. The stimuli-extra-stimulus (S1-S2) method and dynamic S1 pacing protocol were performed to construct APD restitution and to induce APD alternans or VA, respectively, at 10 sites throughout the ventricular chamber. Administration of phorbol-12-myristate-13-acetate (PMA) (100 nM) (n = 15) greatly steepened the restitution curves (Smax > 1) (p < .01) at each site compared to the control group (n = 15). Furthermore, treatment with PMA also induced larger spatial dispersions of Smax (p < .05) and decreased the thresholds of the VA and APD alternans (p < .01). However, perfused with the PKC inhibitor, bisindolylmaleimide (BIM) (500 nM) (n = 10), reversibly flattened the APD restitution curves at each site (Smax < 1), decreased the spatial dispersions of Smax, and increased the thresholds of APD alternans and VA. According to the results of patch-clamp, peak amplitude of L-type Ca2+ current was significantly increased by addition of PMA compared with control (CTL) group (p < .05). Antagonize this current with verapamil (n = 10) can fully inhibited the PMA induced increasing of Smax and inducibility of VA and alternans. CONCLUSION: PKC activation increased the dispersion of APD restitution and thus led to occurrence of VA, which possibly related to the increased Ca2+ influx.

Loss of protein phosphatase 2A regulatory subunit PPP2R5A is associated with increased incidence of stress-induced proarrhythmia.

Background: Protein phosphatase 2A (PP2A) is a serine/threonine-selective holoenzyme that controls Ca2+ homeostasis and contractility of the heart via dephosphorylation of regulatory proteins. In some genetically modified mouse models with increased arrhythmogenicity, a reduced expression of the regulatory subunit B56α of PP2A was found as a concomitant effect. Whether there is a general correlation between the abundance of B56α and the promotion of cardiac arrhythmogenesis remains unclear. Methods: The aim of this study was therefore to investigate the role of PP2A-B56α in the propensity for arrhythmic activity in the heart. The experimental analysis of this question has been addressed by using a mouse model with deletion of the PP2A-B56α gene, PPP2R5A (KO), in comparison to wild-type animals (WT). Evidence for arrhythmogenicity was investigated in whole animal, isolated heart and cardiomyocytes by ECG, recording of monophasic action potential (MAP) induced by programmed electrical stimulation (PES), measurement of Ca2+ transients under increased pacing frequencies and determination of total K+ channel currents (I K). Results: ECG measurements showed a prolongation of QT time in KO vs. WT. KO mice exhibited a higher rate of premature ventricular contractions in the ECG. MAP measurements in Langendorff-perfused KO hearts showed increased episodes of ventricular tachyarrhythmia induced by PES. However, the KO hearts showed values for MAP duration that were similar to those in WT hearts. In contrast, KO showed more myocardial cells with spontaneous arrhythmogenic Ca2+ transient events compared to WT. The whole-cell patch-clamp technique applied to ventricular cardiomyocytes revealed comparable peak potassium channel current densities between KO and WT. Conclusion: These findings support the assumption that a decrease or even the loss of PP2A-B56α leads to an increased propensity of triggered arrhythmias. This could be based on the increased spontaneous Ca2+ tansients observed.

A Late Presentation of Right Common Iliac Vein Stent Embolization to the Right Atrium: Important Management Considerations.

Stent migration is a rare but serious complication of venous stenting, often presenting with chest pain, shortness of breath, and signs of heart failure. Potential complications include arrhythmia, perforation, and valve destruction. Here we present an asymptomatic patient with a late presentation of right common iliac vein stent migration to the right atrium.

A Rare Case of Deglutition-Induced Atrial Fibrillation Secondary to Esophageal Dilation.

Atrial fibrillation (AF) is the most common arrhythmia in the world. However, deglutition-induced tachyarrhythmias are exceptionally rare. Diagnosis relies on a documented history, Holter monitoring and echocardiograms. The mechanism underlying deglutition-induced tachycardia remains uncertain, with leading hypotheses suggesting mechanical left atrial stimulation after esophageal distention or activation of the vagus nerve due to increased intra-esophageal pressure. Lifestyle changes, medications (e.g., beta-blockers and antiarrhythmics), and radiofrequency catheter ablation are viable treatment options. First-line treatment is usually beta-blockers, but they have limited effectiveness due to the poorly understood mechanisms behind this pathological condition. Sodium channel blockers targeting vagal motor fibers decrease esophageal muscle contraction force by reducing axonal transmission, supporting the theory that inhibiting rapid sodium channels may mitigate atrial tachycardias. This mechanism presents a promising approach for managing deglutition-induced atrial fibrillation. We present a unique case of a 58-year-old female diagnosed with deglutition-induced atrial fibrillation secondary to esophageal dilation who was successfully treated with the antiarrhythmic propafenone, supporting the vagus nerve hypothesis.

New Guidelines of Pediatric Cardiac Implantable Electronic Devices: What Is Changing in Clinical Practice?

Guidelines are important tools to guide the diagnosis and treatment of patients to improve the decision-making process of health professionals. They are periodically updated according to new evidence. Four new Guidelines in 2021, 2022 and 2023 referred to pediatric pacing and defibrillation. There are some relevant changes in permanent pacing. In patients with atrioventricular block, the heart rate limit in which pacemaker implantation is recommended was decreased to reduce too-early device implantation. However, it was underlined that the heart rate criterion is not absolute, as signs or symptoms of hemodynamically not tolerated bradycardia may even occur at higher rates. In sinus node dysfunction, symptomatic bradycardia is the most relevant recommendation for pacing. Physiological pacing is increasingly used and recommended when the amount of ventricular pacing is presumed to be high. New recommendations suggest that loop recorders may guide the management of inherited arrhythmia syndromes and may be useful for severe but not frequent palpitations. Regarding defibrillator implantation, the main changes are in primary prevention recommendations. In hypertrophic cardiomyopathy, pediatric risk calculators have been included in the Guidelines. In dilated cardiomyopathy, due to the rarity of sudden cardiac death in pediatric age, low ejection fraction criteria were demoted to class II. In long QT syndrome, new criteria included severely prolonged QTc with different limits according to genotype, and some specific mutations. In arrhythmogenic cardiomyopathy, hemodynamically tolerated ventricular tachycardia and arrhythmic syncope were downgraded to class II recommendation. In conclusion, these new Guidelines aim to assess all aspects of cardiac implantable electronic devices and improve treatment strategies.

The Villain Who Saved the Day: The Paradoxical Value of Amiodarone in Managing Recurrent Ventricular Tachycardia Secondary to Amiodarone-Induced Thyroiditis.

Thyroiditis is a rare and serious complication for patients taking amiodarone. It can manifest with symptoms of hyperthyroidism and serious life-threatening arrhythmias. We present a case of a patient with amiodarone-induced thyrotoxicosis presenting with an electrical storm in which rhythm control was achieved with the utilization of amiodarone.

Sleep apnea and sudden death in the non-cardiac population: A systematic review.

INTRODUCTION: Obstructive sleep apnea (OSA) is one of the main risk factors for cardiovascular diseases and is associated with both morbidity and mortality. OSA has also been linked to arrhythmias and sudden death. OBJECTIVE: To assess whether OSA increases the risk of sudden death in the non-cardiac population. METHODS: This is a systematic review of the literature. The descriptors "sudden death" and "sleep apnea" and "tachyarrhythmias" and "sleep apnea" were searched in the PubMed/Medline and SciELO databases. RESULTS: Thirteen articles that addressed the relationship between OSA and the development of tachyarrhythmias and/or sudden death with prevalence data, electrocardiographic findings, and a relationship with other comorbidities were selected. The airway obstruction observed in OSA triggers several systemic repercussions, e.g., changes in intrathoracic pressure, intermittent hypoxia, activation of the sympathetic nervous system and chemoreceptors, and release of catecholamines. These mechanisms would be implicated in the appearance of arrhythmogenic factors, which could result in sudden death. CONCLUSION: There was a cause-effect relationship between OSA and cardiac arrhythmias. In view of the pathophysiology of OSA and its arrhythmogenic role, studies have shown a higher risk of sudden death in individuals who previously had heart disease. On the other hand, there is little evidence about the occurrence of sudden death in individuals with OSA and no heart disease, and OSA is not a risk factor for sudden death in this population.

Histological and functional assessment of a Takotsubo cardiomyopathy model established by immobilization stress.

INTRODUCTION: Takotsubo cardiomyopathy (TTC), also known as stress-induced cardiomyopathy, resembles acute heart failure syndrome but lacks disease-specific diagnosis and treatment strategies. TTC accounts for approximately 5-6% of all suspected cases of acute coronary syndrome in women. At present, animal models of TTC are often created by large amounts of exogenous catecholamines such as isoproterenol. However, isoproterenol injection cannot fully simulate the onset of stress-induced cardiomyopathy in humans since stress is not an instantaneous event. METHODS: Rats were immobilized for 6 h per day for 1-14 days. To examine whether the TTC model was successful, echocardiography was employed; Elisa detected serum sympathetic activation markers; and the Open-Field test (OFT) was used to analyze behavioral changes in rats after stress. Western blot and histology were used to assess sympathetic remodeling, inflammation levels, and fibrosis; qRT-PCR was used to explore the levels of fibrosis and myocardial hypertrophy. The electrical stability of ventricular was determined by electrophysiological testing. RESULTS: The rats showed severe stress behavior and local sympathetic remodeling of the heart after only 1 day of stress. After 3 days of stress, the induction of ventricular tachyarrhythmia increased prominently. The highest incidence of TTC in rats was at 5 days of immobilization stress. The pathological left ventricular remodeling caused by immobilization (IMO) stress includes inflammatory infiltration, fibrosis, and myocardial hypertrophy. CONCLUSIONS: Our study confirms the hypothesis that IMO stress can mimic Takotsubo cardiomyopathy, and the various effects on the heart depending on the duration of IMO stress. We observed the highest incidence of TTC occurred after 5 days of stress. Furthermore, there is a gradual occurrence of electrical and structural remodeling as the stress duration prolongs.

A case of tachycardia-induced acute kidney injury by renal hypouricemia.

Idiopathic renal hypouricemia is an autosomal recessive hereditary disease, characterized by hypouricemia and high renal fractional excretion of uric acid, and can be complicated by acute kidney injury after anaerobic exercise. However, no report has suggested tachycardia-induced acute kidney injury complicated with renal hypouricemia. We herein report the case of a 12-year-old female with tachycardia-induced acute kidney injury complicated with renal hypouricemia. It is an important issue that the tachycardias and acute kidney injury due to renal hypouricemia can be deteriorating factors for each other through the reactive oxygen species. Learning objective: Renal hypouricemia is rare, with a frequency of 0.2-0.4 %, but is often overlooked and can produce acute kidney injury after exercise. Tachyarrhythmia can be an inducer of acute kidney injury in patients with renal hypouricemia.

Effects of colchicine on the prevention of AF recurrence after atrial ablation: a systematic review and meta-analysis.

BACKGROUND: Catheter ablation has become a widely accepted treatment for atrial fibrillation, but early recurrences remain a challenge, often attributed to inflammatory responses triggered during the procedure. This systematic review and meta-analysis aimed to evaluate the effectiveness of colchicine in preventing short-term AF recurrence post-ablation. METHOD: PubMed, Embase, and Cochrane Library were searched for studies comparing use of colchicine and placebo in patients after AF ablation. Outcomes included AF recurrence, GI side effects, and hospitalization. R program (version 4.3.2) was used for statistical analysis. Heterogeneity was assessed with I2 statistics. RESULTS: Five studies, including 1592 patients, were analyzed. Pooled results revealed no statistically significant decrease in AF recurrence (OR 0.74; 95% CI 0.48-1.12; p = 0.153) and pericarditis rates (OR 0.67; 95% CI 0.26-1.72; p = 0.403) with colchicine use. No significant difference in hospitalization rates was observed between colchicine and placebo groups (OR 1.00; 95% CI 0.63-1.59; p = 0.996). In addition, gastrointestinal side effects were notably higher in the colchicine group (OR 4.84; 95% CI 2.58-9.05; p < 0.001). CONCLUSION: Prophylactic use of colchicine after atrial ablation was not associated with a reduction in AF recurrence and pericarditis rates. In addition, there was no difference in the rate of all-cause hospitalization between the groups, and colchicine use was associated with gastrointestinal adverse events.