Pulsed-Field Ablation in Management of Ventricular Tachycardia: A Systematic Review of Case Reports and Clinical Outcomes.

BACKGROUND: Pulsed-field ablation (PFA) is a cutting-edge technique that employs non-thermal energy to cause cell death by inducing irreversible electroporation of cell membranes. This systematic review evaluates the PFA effectiveness as a potential alternative to radiofrequency and cryo-ablation for treating ventricular tachycardia. METHODS: PubMed, Embase, Scopus, and Web of Science were systematically searched using keywords related to ventricular tachycardia and pulsed-field ablation. Eligible Studies evaluating this therapeutic approach for ventricular tachycardia were included in the final analysis. RESULTS: We included six studies (five case reports and one case series) in our systematic review. Eight (88.8%) of procedures were successful with 100% long-term efficacy. No procedural complications or ventricular tachycardia (VT) recurrence were observed in the cases. CONCLUSION: The absence of complications, high effectiveness, and long-term success rate make PFAs a good VT treatment option. However, PFA safety and efficacy studies for VT treatment are scarce. Thus, larger investigations on this topic are urgently needed.

Structure Activity Optimization of Ryanodine Receptor Modulators for the Treatment of Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia disorder associated with potentially lethal arrhythmias. Most CPVT cases are caused by inherited variants in the ryanodine receptor type-2 (RYR2) gene. OBJECTIVE: To investigate the structure activity relationship of tetracaine derivatives and test a lead compound in a mouse model of CPVT. METHODS: We synthesized >200 tetracaine derivatives and characterized 11 of those. The effects of these compounds on Ca2+ handling in cardiomyocytes from R176Q/+ mice was tested using confocal microscopy. The effects of lead compound MSV1302 on arrhythmia inducibility and cardiac contractility were tested using programmed electrical stimulation and echocardiography, respectively. Plasma and microsomal stability and cytotoxicity assays were also performed. RESULTS: Ca2+ imaging revealed that 4 of 11 compounds suppressed sarcoplasmic reticulum Ca2+ leak through mutant RyR2. Two compounds selected for further testing exhibited an EC50 of 146 nM (MSV1302) and 49 nM (MSV1406), respectively. While neither compound altered baseline ECG intervals, only MSV1302 suppressed stress- and pacing-induced ventricular tachycardia in vivo in R176Q/+ mice. Echocardiography revealed that the lead compound MSV1302 did not negatively impact cardiac inotropy and chronotropy. Finally, compound MSV1302 did not block INa, ICa,L, or IKr, exhibited excellent stability in plasma and microsomes, and was not cytotoxic. CONCLUSION: Structure activity relationship studies of second generation tetracaine derivatives identified lead compound MSV1302 with a favorable pharmacokinetic profile. MSV1302 normalized aberrant RyR2 activity in vitro and in vivo, without altering cardiac inotropy, chronotropy or off-target effects on other ion channels. This compound may be a strong candidate for future clinical studies to determine its efficacy in CPVT patients.

Dofetilide for the treatment of premature ventricular complexes and ventricular tachycardia in patients with structural heart disease.

BACKGROUND: Dofetilide is a class III antiarrhythmic agent approved for the treatment of atrial fibrillation and atrial flutter. Given the efficacy of other class III agents, it has been used off-label for the treatment of premature ventricular complexes (PVCs) and ventricular tachycardias (VTs). OBJECTIVE: The purpose of this study was to determine the efficacy and safety of dofetilide for ventricular arrythmias (VAs). METHODS: In this retrospective cohort study, 81 patients (59 men; age = 60 ± 14 years; LVEF = 0.34 ± 0.16) were admitted for dofetilide initiation to treat PVCs (29), VTs (42) or both (10). A ≥ 80% decrease in PVC burden was defined as a satisfactory response. An ICD was present in 72 patients (89%). Another antiarrhythmic was previously used in 50 patients (62%). Prior catheter ablation had been performed in 33 patients (41%). RESULTS: During intitiation, dofetilide was discontinued in 12 patients (15%) due to QT prolongation (8) and inefficacy to suppress VAs (4). Among the 32 patients with PVCs who successfully started dofetilide, the mean PVC burden decreased from 20 ± 10% to 8 ± 8% at a median follow-up of 2.6 months (p < .001). PVC burden was reduced by ≥80% in only 11/32 patients (34%). During 7 ± 1 years of follow-up, 41/69 patients (59%) continued to have VAs and received appropriate ICD therapies for monomorphic VTs (35) and polymorphic VT/VF (6) at a median of 8.0 (IQR 2.6-33.2) months. Dofetilide had to be discontinued in 50/69 patients (72%) due to inefficacy or intolerance. The composite outcome of VT/VF recurrence, heart transplantation, or death occurred in 6/12 patients (50%) without dofetilide and 49/69 patients (71%) with dofetilide. The event free survival was similar between patients treated with and without dofetilide (log-rank p = .55). CONCLUSIONS: Treatment with dofetilide was associated with a decrease in PVCs, however clinically significant suppression occurred in a minority of patients. Dofetilide failed to suppress the occurrence of VTs in a majority of patients.

An Unusual Case of Anthracycline-Induced Ventricular Tachycardia in Pregnancy.

A 34-year-old woman at 18 weeks' gestation experienced shortness of breath and palpitations after receiving her first dose of doxorubicin for right-sided invasive ductal breast carcinoma. Telemetry monitoring found frequent runs of nonsustained ventricular tachycardia that was treated with metoprolol tartrate. No further arrhythmias occurred with subsequent doses of chemotherapy.

Ablation of Focal Atrial Tachycardia from a Large Left Atrial Diverticulum Using 3D Printing.

We present a case of a 45-year-old male with symptomatic supraventricular tachycardia. Electrophysiology study and 3-dimensional (3D) electroanatomic mapping showed a focal atrial tachycardia originating from a large left atrial diverticulum. Due to the unusual anatomy, 3D printing models were used to aid successful catheter ablation of the atrial tachycardia.

Pacing-facilitated Short-long-short Sequences Leading to Ventricular Tachyarrhythmias: A Brief Report.

Pacing-induced recurrent short-long-short sequences constitute an important yet overlooked mechanism for triggering ventricular tachyarrhythmias in patients with cardiovascular implantable electric devices. A careful and thorough retrospective analysis of patients' electrograms allows for a timely diagnosis with appropriate management.

Detection of Ventricular Tachycardia by an Implantable Cardiac Monitor 8 Months Post-myocardial Infarction.

Following a non-ST-elevation myocardial infarction (MI), a 68-year-old hypertensive, severely obese woman with 45% left ventricular ejection fraction underwent an implantable cardiac monitor (ICM) insertion. After 8 months, the ICM remotely transmitted multiple non-sustained ventricular tachycardia episodes. Symptomatic during these events, the patient underwent an invasive electrophysiologic stimulation, which induced ventricular arrhythmia. Subsequently, implantable cardioverter-defibrillator implantation was recommended. Continuous remote monitoring via an ICM detected critical arrhythmias in this post-MI patient, facilitating timely intervention.

Atrial tachycardia originating from a right atrial free wall diverticulum: case report.

Background: Atrial tachycardia (AT) is an arrhythmic disorder originating from the atrium, independent of the atrioventricular node, and includes various types based on different mechanisms such as abnormal automaticity, triggered activity, and re-entry. These mechanisms are often related to specific anatomical structures. Focal AT, though relatively rare, typically arises from well-known locations in the left and right atria, such as the pulmonary veins, mitral valve annulus, crista terminalis, and coronary sinus ostium. Case summary: We report a rare case of AT originating from a diverticulum in the right atrial free wall. The patient experienced recurrent AT episodes resistant to standard treatments. Detailed electrophysiological mapping identified the unusual origin of the tachycardia from a right atrial free wall diverticulum. Catheter ablation was successfully performed, leading to the resolution of the arrhythmia, with the patient remaining symptom-free during follow-up. Discussion: This case expands the understanding of AT origins, highlighting the right atrial free wall diverticulum as a potential, though rare, source of tachycardia. The case emphasizes the importance of comprehensive electrophysiological mapping, especially in atypical presentations of AT. Successful ablation in this instance underscores the potential for targeted interventions even in uncommon anatomical sites. Further studies are needed to assess the prevalence and clinical significance of AT arising from such rare locations.

Classification of underlying paroxysmal supraventricular tachycardia types using deep learning of sinus rhythm electrocardiograms.

Background: Obtaining tachycardia electrocardiograms (ECGs) in patients with paroxysmal supraventricular tachycardia (PSVT) is often challenging. Sinus rhythm ECGs are of limited predictive value for PSVT types in patients without preexcitation. This study aimed to explore the classification of atrioventricular nodal reentry tachycardia (AVNRT) and concealed atrioventricular reentry tachycardia (AVRT) using sinus rhythm ECGs through deep learning. Methods: This retrospective study included patients diagnosed with either AVNRT or concealed AVRT, validated through electrophysiological studies. A modified ResNet-34 deep learning model, pre-trained on a public ECG database, was employed to classify sinus rhythm ECGs with underlying AVNRT or concealed AVRT. Various configurations were compared using ten-fold cross-validation on the training set, and the best-performing configuration was tested on the hold-out test set. Results: The study analyzed 833 patients with AVNRT and 346 with concealed AVRT. Among ECG features, the corrected QT intervals exhibited the highest area under the receiver operating characteristic curve (AUROC) of 0.602. The performance of the deep learning model significantly improved after pre-training, showing an AUROC of 0.726 compared to 0.668 without pre-training (p < 0.001). No significant difference was found in AUROC between 12-lead and precordial 6-lead ECGs (p = 0.265). On the test set, deep learning achieved modest performance in differentiating the two types of arrhythmias, with an AUROC of 0.708, an AUPRC of 0.875, an F1-score of 0.750, a sensitivity of 0.670, and a specificity of 0.649. Conclusion: The deep-learning classification of AVNRT and concealed AVRT using sinus rhythm ECGs is feasible, indicating potential for aiding in the non-invasive diagnosis of these arrhythmias.

Inappropriate Therapies in Modern Implantable Cardioverter Defibrillators: A Propensity Score-matched Comparison between Single- and Dual-Chamber Discriminators in Single-Chamber devices THe sINGle lead Study (THINGS Study).

BACKGROUND: In patients with implantable cardioverter-defibrillators (ICDs), inappropriate therapies (ITs) are often caused by supraventricular tachyarrhythmias (SVTs). OBJECTIVE: To estimate the incidence of IT in modern single-lead ICDs. METHODS: The THINGS study enrolled patients with single-lead ICDs with two SVT discrimination modalities: dual-chamber (DC) via an atrial floating dipole or single-chamber (SC) with morphology criterion. All devices were programmed with two-zone therapy: (i) VT zone from 170 beats-per-minute with ≥15 seconds (≥36 beats) detection time and SVT discriminators, (ii) VF zone from 214 beats-per-minute with ≥7 seconds (≥24 beats) detection time. The primary endpoint was the first occurrence of IT, adjudicated by an independent board. RESULTS: A total of 526 patients (median age 66 years, 83% males), 183 (34.8%) with DC and 343 (65.2%) with SC discrimination, were followed for a median of 2.2 years. The incidence rate of IT was 4.2% (95% CI, 2.7%-6.4%) at 1 year and 7.1% (95% CI, 5.0%-9.9%) at 2 years. Younger age (adjusted HR 0.97, 95% CI 0.95-0.99, P=0.013) and history of atrial fibrillation (adjusted HR 2.67, 95% CI 1.30-5.46, P=0.007) were significantly associated with increased IT risk. In a propensity-score matched comparison, DC discrimination showed a trend towards reduced IT rates compared to SC discrimination in the VT zone (1-year incidence 1.8% vs. 3.5%, P=0.105). CONCLUSION: High-rate VF cutoff and prolonged detection times programming resulted in a low IT rate in single-lead ICD patients with modern SVT discriminators. A trend favoring the DC system was observed in the VT zone.

Premature ventricular contraction patterns associated with nonsustained ventricular tachycardia.

BACKGROUND: Occurrence of nonsustained ventricular tachycardia (NSVT) is associated with negative outcomes. It is not clear whether specific electrocardiographic characteristics of premature ventricular contractions (PVCs) are associated with the occurrence of NSVT. The aim of this study was to identify electrocardiographic patterns associated with the presence of NSVT during 24-h electrocardiographic monitoring in patients with >10 PVCs per hour. METHODS: This was a retrospective, observational, cross-sectional study. We reviewed consecutive patients who received 24-h ECG monitoring performed at a single outpatient cardiology center. Patients who received 24-h electrocardiographic monitoring, with a PVC burden ≥10 PVCs/h were included. Occurrence of NSVT during 24-h electrocardiographic monitoring was the main outcome. RESULTS: A total of 343 patients were analyzed (mean [SD] age, 69.7 [12.5] years; 177 men [51.6 %]). NSVT occurred in 72 patients who were compared with 271 patients without NSVT. The novel term "premature beat ratio", which aims to correlate the coupling interval and compensatory pause, was introduced; a value >0.5 was independently associated with NSVT according to the multivariate model (OR = 3.73, 95 % CI = 1.57-8.82; P = 0.002). PVC burden (OR = 1.09, 95 % CI = 1.02-1.17; P = 0.006), and triplets (OR = 18.19, 95 % CI = 7.32-45.18 P = 0.0) were also associated with NSVT in the multivariate model. CONCLUSION: These findings suggest that patients with a high PVC burden, triplets, and a premature beat ratio greater than 0.5 have an increased probability of presenting with NSVT and may benefit from more rigorous follow-up.

Usefulness of tissue tracking to differentiate tachycardia-induced cardiomyopathy from dilated cardiomyopathy in patients admitted for heart failure.

INTRODUCTION: Differentiation of tachycardia-induced cardiomyopathy (TIC) from dilated cardiomyopathy (DCM) in patients admitted for heart failure (HF) with left ventricular dysfunction and supraventricular tachyarrhythmia (SVT) remains challenging. The role of tissue tracking (TT) in this setting remains unknown. METHODS: Forty-three consecutive patients admitted for HF due to SVT with left ventricular ejection fraction (LVEF) < 50% undergoing CMR were retrospectively included. Those eventually evolving to LVEF > 50% at follow-up were classified as TIC and those maintaining a LVEF < 50% were classified as DCM. Clinical, echocardiography, and CMR findings, including TT, were analyzed to predict LVEF recovery. RESULTS: Twenty-five (58%) patients were classified as TIC. Late gadolinium enhancement (LGE) was more frequent in DCM group (61% vs 16%, p = 0.004). Left ventricle (LV) peak systolic radial velocity and peak diastolic radial strain rate were lower in DCM group (7.24 ± 4.44 mm/s vs 10.8 ± 4.5 mm/s; p = 0.015 and -0.12 ± 0.33 1/s vs -0.48 ± 0.51 1/s; p = 0.016, respectively). Right ventricle (RV) peak circumferential displacement was lower in patients with TIC (0.2 ± 1.3 vs 1.3 ± 0.9°; p = 0.009). In the multivariate analysis, diabetes (p = 0.046), presence of LGE (p = 0.028), LV peak systolic radial velocity < 7.5 mm/s (p = 0.034), and RV peak circumferential displacement > 0.5° (p = 0.028) were independent predictors of lack of LVEF recovery. CONCLUSION: In the setting of acute HF with LV dysfunction related to SVT, diabetes, LGE, LV peak systolic velocity, and RV peak circumferential displacement are independent predictors of lack of LVEF recovery and, therefore, represent clinically useful parameters to differentiate TIC from DCM.

Invasive management of atrial tachycardias using a novel lattice-tip catheter combining high-density mapping and dual ablation properties: initial real-world experience.

BACKGROUND: Invasive management of atrial tachycardias(ATs) requires proper diagnosis of the mechanism followed by elimination of the responsible substrate. A novel lattice-tip catheter with both high-density mapping and dual ablation properties(radiofrequency-RF/pulsed field ablation-PFA) has been recently introduced for catheter ablation of atrial fibrillation. We present the first study to assess its performance in the management of ATs (diagnostic and therapeutic). METHODS: Patients with documented ATs were selected. Activation mapping was used for the establishment of the AT mechanism. Confirmation with entrainment was performed, whenever appropriate. Accuracy of the activation mapping in diagnosis, acute ablation efficacy, and procedural characteristics were the study endpoints. RESULTS: Twenty patients were included (12 cavotricuspid isthmus-dependent atrial flutters, 5 mitral flutters, 2 roof flutters, and 2 focal ATs). Proper diagnosis was established by activation mapping in all cases. The mean mapping time was 7.85 ± 3.06 min with 296.82 ± 150.9 mean mapping points/minute. The mean ablation time was 54.25 ± 42.97 s. Conversion to sinus rhythm during ablation was achieved in all cases with the exception of a roof flutter that converted to mitral flutter and a case of a parahisian AT in which ablation was not attempted. Patients that received ablation did not experience any arrhythmia recurrence in a mean follow up of 4.14 ± 0.91 months. No major or minor complications occurred. CONCLUSION: The lattice-tip catheter and its dedicated electroanatomical mapping system provided sufficiently detailed activation mapping for the diagnosis of the AT mechanism. The delivered lesions were highly effective acutely, with no adverse events. However, limitations exist and should be acknowledged.