Treatment of ventricular arrhythmias: What's New?

Palliative Stereotactic Body Radiation Therapy for the Treatment of Refractory Ventricular Tachycardia

Stereotactic body radiation therapy (SBRT) is a promising noninvasive treatment for ventricular tachycardia (VT) that delivers targeted ablative energy to arrhythmogenic regions. Typically reserved for patients with VT refractory to conventional therapies, SBRT offers a viable option for individuals who are ineligible for invasive procedures due to high-risk profiles and multiple comorbidities. We report the case of a 62-year-old patient with refractory VT, deemed unsuitable for further interventions, who underwent SBRT and experienced a reduction in VT episodes. This case highlights the potential palliative application of SBRT in addressing the growing population of older patients with complex comorbid conditions.

Intravascular Sympathetic Stimulation to Facilitate Catheter Ablation of Premature Ventricular Complexes

Importance

Infrequent intraprocedural premature ventricular complexes (PVCs) limit the efficacy of catheter ablation. Intravascular stimulation of sympathetic nerves via vertebral veins (VVs) has been used to activate cardiac sympathetic tone and may promote PVCs.

Objective

To characterize the ability of direct electrical sympathetic stimulation via VVs to induce PVCs at the time of catheter ablation.

Design, Setting, and Participants

This prospective case series involved adult patients undergoing catheter ablation of PVCs, with rare or absent PVCs despite standard provocation, at the Hospital of the University of Pennsylvania between 2022 and 2024. Stimulation was performed via the left VV (20 Hz, up to 25 mA).

Main Outcomes and Measures

The primary outcome was PVC frequency, assessed before, during, and after stimulation. A multilevel mixed-effects Poisson regression was used to compare the rate of PVCs during the procedure.

Results

Fifteen patients (mean [SD] age, 60 [17] years; 10 male [71%]) had a mean (SD) preprocedure PVC burden of 16.3% (8.6%) (median [IQR], 17.0% [11.5%-21.5%]), and 7 of 15 had undergone at least 1 prior unsuccessful ablation. Provocation of PVCs was attempted with isoproterenol, atrial and ventricular burst pacing, and minimal sedation in all patients before VV stimulation. Throughout the 10-minute period before VV stimulation, patients had a mean (SD) of 1.3 (1.4) PVCs (median [IQR], 1.0 [0.0-2.5] PVCs). During VV stimulation, PVCs were noted in all patients (mean [SD], 8.2 [5.7] PVCs per minute; median [IQR], 6.0 [4.5-13.0] PVCs per minute). In the 10-minute period after VV stimulation, patients had a mean (SD) of 5.1 (6.6) PVCs per minute (median [IQR], 3.0 [0.5-6.5] PVCs per minute). After VV stimulation, ablation was guided by activation mapping in 7 patients and by pace mapping alone in the remaining patients. Postablation monitoring demonstrated a mean (SD) 1.3% (2.3%) burden of PVCs (median [IQR], 0.0% [0.0%-2.5%]), with 9 of 15 patients having less than 1% burden of PVCs. There were no adverse events related to VV stimulation.

Conclusions and Relevance

These findings suggest that intravascular sympathetic stimulation via the VV can be used to safely provoke PVCs during catheter ablation.

Stereotactic arrhythmia radioablation (STAR) opens a new era in the treatment of arrhythmias?

Tachyarrhythmias are common cardiovascular emergencies encountered in clinical practice. Among these, atrial fibrillation (AF) and ventricular tachycardia (VT) pose significant hazards due to their prevalence and severity. Initially, non-invasive pharmacological antiarrhythmic interventions were the primary treatment modality; however, due to their limited control rates and side effects, invasive therapies have been introduced in recent years. These include catheter ablation, alcohol ablation, cardiac implantable electronic devices, and heart transplantation. Nonetheless, for some patients, invasive treatments do not offer a definitive cure for arrhythmias and carry the risk of recurrence, especially with AF and VT, where the relapse rates are high and the treatment for VT is correlated with the type of tachycardia present. Currently, novel non-invasive treatment methods are emerging, with stereotactic radioablation therapy becoming an effective alternative for the management of refractory tachyarrhythmias. This review provides an overview of the application background of Stereotactic Arrhythmia Radioablation (STAR) therapy and promising results from its use in animal models and clinical applications.

Frontiers in premature beats research: a bibliometric analysis

Background

This study aimed to assess the scientific results and activities of premature beats research from a global perspective.

Methods

Publications related to premature beats published between 2003 and 2024 were identified and selected from the Web of Science core collection. VOSviewer was used to conduct co-authorship, co-citation, and co-occurrence analyses of the authors, organizations, countries/regions, references, sources, cited authors, and keywords.

Results

In total, 5,283 publications on the topic of premature beats were identified from the Web of Science core collection. The number of publications on this topic has steadily grown since 2003. Fred Morady, Frank Bogun and Krit Jongnarangsin were the top three researchers with the strongest total link strengths. The University of Washington, Johns Hopkins University, and the University of Minnesota are the top three organizations with the strongest total link strengths. The United States has made the greatest contributions to the field of premature beats. Haïssaguerre, M et al.'s publication in The New England Journal of Medicine in 1998 entitled "Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins" is the most cited reference. The most cited references come from the journal named Circulation. Haïssaguerre, M has the highest number of citations. The keywords for all current publications can be divided into four categories: "mortality rate," "risk and prevention," "mechanism," and "classification and treatment."

Conclusions

This bibliometric study provides insights into the current status and research trends in premature beats over more than 20 years. Future research will focus on an in-depth exploration of the nature of premature beats, especially ventricular premature beats, mastering the development law of premature beats, and optimizing existing detection methods.

Predictors of Mortality Following Aortic Valve Replacement in Aortic Stenosis Patients

Background: Understanding of the risk factors for the development of adverse outcomes after aortic valve replacement is necessary to develop timely preventive measures and to improve the results of surgical treatment. Methods: We analyzed patients with aortic stenosis (n = 742) who underwent surgical treatment in the period 2014−2020. The average age was 63 (57;69) years—men 58%, women 42%. Results: The hospital mortality rate was 3% (22 patients). The following statistically significant threshold values (cut-off points) were obtained in the ROC analysis: aortic cross-clamp time > 93 min AUC (CI) 0.676 (0.640−0.710), p = 0.010; cardiopulmonary bypass time > 144 min AUC (CI) 0.809 (0.778−0.837), p < 0.0001, hemoglobin before op <120 g/L. AUC (CI) 0.762 (0.728−0.793), p < 0.0001, hematocrit before op <39% AUC (CI) 0.755 (0.721−0.786), p < 0.001, end-diastolic dimension index >2.39 AUC (CI) 0.647 (0.607−0.686), p = 0.014, end-systolic dimension index > 1.68 AUC (CI) 0.657 (0.617−0.695), p = 0.009. Statistically significant independent predictors of hospital mortality were identified: BMI > 30 kg/m2 (OR 2.84; CI 1.15−7.01), ischemic heart disease (OR 3.65; CI 1.01−13.2), diabetes (OR 3.88; CI 1.38−10.9), frequent ventricular ectopy before operation (OR 9.78; CI 1.91−50.2), mitral valve repair (OR 4.47; CI 1.76−11.3), tricuspid valve repair (OR 3.06; CI 1.09−8.58), 3 and more procedures (OR 4.44; CI 1.67−11.8). Conclusions: The hospital mortality rate was 3%. The main indicators associated with the risk of death were: diabetes, overweight (body mass index more than 30 kg/m2), frequent ventricular ectopy before surgery, hemoglobin level below 120 g/L, hematocrit level below 39%, longer cardiopulmonary bypass time and aortic cross-clamp time, additional mitral and tricuspid valve interventions.

Impact of High-Dose Irradiation on Human iPSC-Derived Cardiomyocytes Using Multi-Electrode Arrays: Implications for the Antiarrhythmic Effects of Cardiac Radioablation

Cardiac radioablation is emerging as an alternative option for refractory ventricular arrhythmias. However, the immediate acute effect of high-dose irradiation on human cardiomyocytes remains poorly known. We measured the electrical activities of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) upon irradiation with 0, 20, 25, 30, 40, and 50 Gy using a multi-electrode array, and cardiomyocyte function gene levels were evaluated. iPSC-CMs showed to recover their electrophysiological activities (total active electrode, spike amplitude and slope, and corrected field potential duration) within 3-6 h from the acute effects of high-dose irradiation. The beat rate immediately increased until 3 h after irradiation, but it steadily decreased afterward. Conduction velocity slowed in cells irradiated with ≥25 Gy until 6-12 h and recovered within 24 h; notably, 20 and 25 Gy-treated groups showed subsequent continuous increase. At day 7 post-irradiation, except for cTnT, cardiomyocyte function gene levels increased with increasing irradiation dose, but uniquely peaked at 25-30 Gy. Altogether, high-dose irradiation immediately and reversibly modifies the electrical conduction of cardiomyocytes. Thus, compensatory mechanisms at the cellular level may be activated after the high-dose irradiation acute effects, thereby, contributing to the immediate antiarrhythmic outcome of cardiac radioablation for refractory ventricular arrhythmias.

Ventricular tachycardia originating from the His bundle: A case report

BACKGROUND

Ventricular tachycardia (VT) commonly occurs among patients with heart failure and can even cause sudden cardiac death. VT originating from the His bundle branch has been rarely reported. We present the case of a patient with VT from the His bundle branch.

CASE SUMMARY

A 58-year-old female complained of paroxysmal palpitations and dizziness for approximately 6 mo. She had a history of fatty liver and cholecystitis, and carotid atherosclerosis could not be excluded from the ultrasound results. An evaluation of the electrocardiogram obtained after admission showed spontaneous conversion between two different morphologies. The possible electrophysiologic mechanism suggested that the dual-source VT originated from the same source, the His bundle branch. Finally, the His bundle branch was ablated, and a dual-chamber pacemaker was inserted into the patient’s heart. No further VT occurred during the 3-year follow-up after hospital discharge.

CONCLUSION

The diagnosis of VT originating from the His bundle is rare and difficult to establish. The results of this study showed VT originating from the His bundle based on a careful evaluation of the electrocardiogram, and the diagnosis was confirmed by an intracardiac electrophysiologic examination.

The Efficacy Comparison Between Guan-Fu Base A Hydrochloric Injection vs. Propafenone Hydrochloric Injection in the Treatment of Arrhythmia: Systemic Review and Meta-Analysis

Objective: To determine using a systematic assessment and meta-analysis if GFA injection is an appropriate substitute of propafenone for arrhythmic. Design: Conduct a systematic review and meta-analysis of randomized controlled trials. Data Source: PubMed, Web of Science, Cochrane Library, Embase, Wan-Fang Database, VIP, CNKI, and Sino Med from their inception to 7 March 2021. Eligibility Criteria for Selecting Studies: Inclusion of randomized controlled trials, which draws a comparison between GFA and propafenone. Evaluation of study integrity and conducted an extraction of independent data. Main Outcome Measure: Efficacy for supraventricular tachycardia, it is considered effective if it is reversed within 40 min (without considering recurrence); for premature ventricular beats, if they are reduced by more than 50% within 6 h. Results: Included in this current study are 1,294 research subjects pooled from 14 clinical studies. From the pooled assessment, GFA is demonstrated to be the equivalent of propafenone regarding the potency of effectiveness for tachycardia (RR = 1.11, 95% CI: 0.96, 1.28, P = 0.15). The subset analysis indicated that GFA has a better effect on premature ventricular beats (RR = 1.35, 95% CI: 1.07, 1.70, P = 0.01) and a similar effect on supraventricular tachycardia (RR = 1.07, 95% CI: 0.98, 1.12, P = 0.21). GFA effectiveness is lesser than propafenone in the case of mean converting time (WMD = -1.18, 95% CI: -2.30, -0.07, P = 0.04), systolic blood pressure (WMD = -3.53, 95% CI: -6.97, -0.09, P = 0.04), and QRS complex (WMD = -3.82, 95% CI: -6.96, -0.69, P = 0.02). Both GFA and propafenone have identical effects for diastolic blood pressure, heart rate, P-R interval, and QTc interval. Conclusion: A meta-analysis of RCTs was performed across 14 clinical trials, whereby 1,294 patients are used as research subjects. From the results, it is revealed that the effect exhibited by GFA injection is similar to the propafenone injection when treating premature ventricular beats or supraventricular tachycardia. Nevertheless, in certain academic disciplines, it was found that GFA is safer and beneficial compared to propafenone. Based on facts from relevant studies, GFA is deemed applicable during clinical practice. Systematic Review Registration: https://www.inplasy.com/inplasy-2021-3-0077/, identifier: INPLASY202130077.

Flecainide in Ventricular Arrhythmias: From Old Myths to New Perspectives

Flecainide is an IC antiarrhythmic drug (AAD) that received in 1984 Food and Drug Administration approval for the treatment of sustained ventricular tachycardia (VT) and subsequently for rhythm control of atrial fibrillation (AF). Currently, flecainide is mainly employed for sinus rhythm maintenance in AF and the treatment of idiopathic ventricular arrhythmias (IVA) in absence of ischaemic and structural heart disease on the basis of CAST data. Recent studies enrolling patients with different structural heart diseases demonstrated good effectiveness and safety profile of flecainide. The purpose of this review is to assess current evidence for appropriate and safe use of flecainide, 30 years after CAST data, in the light of new diagnostic and therapeutic tools in the field of ischaemic and non-ischaemic heart disease.

Regulatory mechanism of calcium/calmodulin-dependent protein kinase II in the occurrence and development of ventricular arrhythmia (Review)

Ventricular arrhythmia (VA) is a highly fatal arrhythmia that involves multiple ion channels. Of all sudden cardiac death events, ~85% result from VAs, including ventricular tachycardia and ventricular fibrillation. Calcium/calmodulin-dependent pro-tein kinase II (CaMKII) is an important ion channel regulator that participates in the excitation-contraction coupling of the heart, and as such is important for regulating its electrophysiological function. CaMKII can be activated in a Ca²⁺/calmodulin (CaM)-dependent or Ca²⁺/CaM-independent manner, serving a key role in the occurrence and development of VA. The present review aimed to determine whether activated CaMKII induces early afterdepolarizations and delayed afterdepolarizations that result in VA by regulating sodium, potassium and calcium ions. Assessing VA mechanisms based on the CaMKII pathway is of great significance to the clinical treatment of VA and the de-velopment of effective drugs for use in clinical practice.

In vitro discovery of novel prokaryotic ion channel candidates for antiarrhythmic gene therapy

Sudden cardiac death continues to have a devastating impact on public health prompting the continued efforts to develop more effective therapies for cardiac arrhythmias. Among different approaches to normalize function of ion channels and prevent arrhythmogenic remodeling of tissue substrate, cardiac cell and gene therapies are emerging as promising strategies to restore and maintain normal heart rhythm. Specifically, the ability to genetically enhance electrical excitability of diseased hearts through voltage-gated sodium channel (VGSC) gene transfer could improve velocity of action potential conduction and act to stop reentrant circuits underlying sustained arrhythmias. For this purpose, prokaryotic VGSC genes are promising therapeutic candidates due to their small size (<1kb) and potential to be effectively packaged in adeno-associated viral (AAV) vectors and delivered to cardiomyocytes for stable, long-term expression. This article describes a versatile method to discover and characterize novel prokaryotic ion channels for use in gene and cell therapies for heart disease including cardiac arrhythmias. Detailed protocols are provided for: (1) identification of potential ion channel candidates from large genomic databases, (2) candidate screening and characterization using site-directed mutagenesis and engineered human excitable cell system and, (3) candidate validation using electrophysiological techniques and an in vitro model of impaired cardiac impulse conduction.