This study investigates the cardiac safety concerns related to TASER discharges centering on a pivotal case that marked the first TASER-related fatality in South Korea. Employing Pratt et al.\'s theoretical framework, the research evaluates the potential for ventricular fibrillation (VF) from these discharges. The methodology incorporated a high-resolution waveform analysis using sophisticated equipment and considered specific incident details, including dart impact locations verified through a forensic examination. A human body impedance of 500 Ω, chosen based on empirical studies and coupled with non-inductive resistance for high-voltage handling, was utilized in the model. By applying a heart-current factor from IEC 60479 standards, the study found a VF risk of up to 5% depending on the impact location and current pathways. In this specific case, although the calculated risk did not exceed critical thresholds, the VF risk was high enough to suggest that TASER discharges played a role in the fatal outcome. This study underscores the importance of dart impact location in TASER safety evaluations, contributing to a broader understanding of TASER cardiac risks and providing a basis to advocate for rigorous safety protocols.

OBJECTIVE: One treatment option for refractory ventricular arrythmias is stellate ganglion block (SGB). We examined differences in SGB success by patient and arrhythmia characteristics and predictors of successful SGB.
RESULTS: This was a multicenter analysis of patients treated for refractory ventricular arrythmias in the Czech Republic and the United States. The primary outcome was absence of ventricular arrythmias at 24 h post SGB. SGB effectiveness was examined according to aetiology of cardiomyopathy, arrhythmia type, laterality of SGB, presence of inotropes, and presence of mechanical circulatory support. Binary logistic regression was used to examine variables associated with the primary outcome. In total there were 117 patients with refractory ventricular arrythmias treated with SGB. Overall, the mean age was 63.5 ± 11.0 years, majority of patients were male (94.0%), White (87.2%), and had an implantable cardioverter defibrillator in situ (70.1%). There were no differences in efficacy of SGB based on aetiology of cardiomyopathy (P = 0.623), arrhythmia type (0.852), laterality of block (P = 0.131), and presence of inotropes (P = 0.083). Multivariable analysis demonstrated that increased age was associated with decreased odds of SGB success (odds ratio: 0.96, confidence interval: 0.92-0.99, P = 0.039) whereas increased left ventricular ejection fraction trended towards increased odds of SGB success (odds ratio: 1.05, confidence interval: 0.995-1.11, P = 0.077).
CONCLUSIONS: In this multicentre experience, SGB was similarly effective despite the aetiology of cardiomyopathy, type of arrhythmia, laterality, and inotropic or mechanical support. SGB was less effective for the suppression of ventricular arrythmias at 24 h for the elderly.

UNASSIGNED: Ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) are the most treatable causes of out-of-hospital cardiac arrest (OHCA). Yet, it remains unknown if defibrillator pad position, placement in the anterior-posterior (AP) or anterior-lateral (AL) locations, impacts patient outcomes in VF or pVT OHCA.
UNASSIGNED: To determine the association between initial defibrillator pad placement position and OHCA outcomes for patients presenting with VF or pVT.
UNASSIGNED: This prospective cohort study included patients with OHCA and VF or pVT treated by a single North American emergency medical services (EMS) agency from July 1, 2019, through June 30, 2023. The study included patients with OHCA treated by a large suburban fire-based EMS agency that covers a population of 550 000. Consecutive patients with an initial EMS-assessed rhythm of VF or pVT receiving EMS defibrillation were included. Pediatric patients (younger than 18 years), interfacility transfers, arrests of obvious traumatic etiology, and patients with preexisting do-not-resuscitate status were excluded.
UNASSIGNED: AP or AL pad placement.
UNASSIGNED: Return of spontaneous circulation (ROSC) at any time with secondary outcomes of pulses present at emergency department (ED) arrival, survival to hospital admission, survival to hospital discharge, and functional survival at hospital discharge (cerebral performance category score of 2 or less). Measures included adjusted odds ratios (aOR), multivariable logistic regressions, and Fine-Gray competing risks regression.
UNASSIGNED: A total of 255 patients with OHCA were included (median [IQR] age, 66 [55-74] years; 63 females [24.7%]), with initial pad positioning documented as either AP (158 patients [62.0%]; median [IQR] age, 65 [54-74] years; 37 females [23.4%]) or AL (97 patients [38.0%]; median [IQR] age, 66 [57-74] years; 26 females [26.8%]). Patients with AP placement had higher adjusted odds ratio (aOR) of ROSC at any time (aOR, 2.64 [95% CI, 1.50-4.65]), but not significantly different odds of pulses present at ED arrival (1.34 [95% CI, 0.78-2.30]), survival to hospital admission (1.41 [0.82-2.43]), survival to hospital discharge (1.55 [95% CI, 0.83-2.90]), or functional survival at hospital discharge (1.86 [95% CI, 0.98-3.51]). Competing risk analysis found significantly greater cumulative incidence of ROSC among those at risk with initial AP placement compared with AL (subdistribution hazard ratio, 1.81 [95% CI, 1.23-2.67]; P = .003).
UNASSIGNED: In this cohort study of patients with OHCA and VF or pVT, AP defibrillator pad placement was associated with higher ROSC compared with AL placement.

BACKGROUND: Normally-functioning implantable cardioverter-defibrillators (ICDs) with intact lead systems occasionally fail to deliver therapy for ventricular tachycardia/ fibrillation (VT/VF) or deliver it only after clinically-significant delays (\"failure-to-treat\").
OBJECTIVE: To investigate ICD failure-to-treat VT/VF in a large patient cohort.
METHODS: We searched the United States (US) Food and Drug Association\'s online Manufacturer and User Facility Device Experience (MAUDE) database from 2019 to 2023 for manufacturer-verified reports in which normally-functioning ICDs failed to treat VT/VF.
RESULTS: We identified 854 reports classified as deaths (n=96, 11.2%), injuries (n=585, 68.5%), or malfunctions (n=173, 20.4%) for normally-functioning ICDs. The most common causes were misclassification as supraventricular tachycardia (SVT) or atrial fibrillation (AF) (54.8%), undersensing (21.1%), and failure to satisfy programmed rate/duration criteria (8.7%). Most events caused by misclassification as SVT/AF (89.5%) and failure to satisfy rate/duration criteria (70.3%) were VT; most caused by undersensing were either VF (54.4%) or not specified as VT or VF (19.4%). Undersensing caused 65.6% of deaths, although it comprised only 21.1% of reports. In the United States, the number of reports increased faster than that of ICD patients.
CONCLUSIONS: In the largest reported series of failure-to-treat VT/VF by normally-functioning ICDs, the most common cause was misclassification of VT as SVT/AF; the most common cause of death was undersensing of VF. Although relatively few patients with normally-functioning ICDs experience failure-to-treat VT/VF, the absolute number of verified MAUDE reports suggests that more work is needed to quantify the magnitude of the problem, identify root causes, and develop solutions.

OBJECTIVE: Known predictors of major arrhythmic events (MAE) in patients with ischemic cardiomyopathy (ICM) include previous MAE and left ventricular ejection fraction (LVEF) ≤35%. Myocardial scars detected by perfusion imaging in ICM have been linked to MAE, but the prognostic significance of hibernating myocardium (HM) is unclear. The objective was to predict major arrhythmic events (MAE) from combined 13N-ammonia (NH3) and 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in ischemic cardiomyopathy (ICM).
RESULTS: Consecutive patients with ICM undergoing combined NH3- and FDG-PET/CT were included. HM was quantified in relation to total left ventricular myocardium (i.e. ≥7% is large). The primary outcome was MAE (sudden cardiac death, ICD therapy, sustained ventricular tachycardia/fibrillation).Among 254 patients, median baseline LVEF was 35% (IQR 28-45) and 10% had an ICD. PET/CT identified ischemia in 94 (37%), scar in 229 (90%) and HM in 195 (77%) patients. Over a median follow-up of 5.4 (IQR 2.2-9.5) years, MAE occurred in 34 patients (13%). Large HM was associated with a lower incidence of MAE (HR 0.31, 95% CI 0.1-0.8, p=0.001). After multivariate adjustment for history of MAE, LVEF ≤35% and scar ≥10%, large HM remained significantly associated with a lower incidence of MAE (p=0.016). LVEF improved over time among patients with large HM (p=0.006) but did not change in those without (p=0.610) or small HM (p=0.240).
CONCLUSIONS: HM conveys a lower risk of MAE in patients with ICM. This may be explained by an increase in LVEF when a large extent of HM is present.

Myocardial edema is a common symptom of pathological processes in the heart, causing aggravation of cardiovascular diseases and leading to irreversible myocardial remodeling. Patient-based studies show that myocardial edema is associated with arrhythmias. Currently, there are no studies that have examined how edema may influence changes in calcium dynamics in the functional syncytium. We performed optical mapping of calcium dynamics on a monolayer of neonatal rat cardiomyocytes with Fluo-4. The osmolality of the solutions was adjusted using the NaCl content. The initial Tyrode solution contained 140 mM NaCl (1T) and the hypoosmotic solutions contained 105 (0.75T) and 70 mM NaCl (0.5T). This study demonstrated a sharp decrease in the calcium wave propagation speed with a decrease in the solution osmolality. The successive decrease in osmolality also showed a transition from a normal wavefront to spiral wave and multiple wavelets of excitation with wave break. Our study demonstrated that, in a cellular model, hypoosmolality and, as a consequence, myocardial edema, could potentially lead to fatal ventricular arrhythmias, which to our knowledge has not been studied before. At 0.75T spiral waves appeared, whereas multiple wavelets of excitation occurred in 0.5T, which had not been recorded previously in a two-dimensional monolayer under conditions of cell edema without changes in the pacing protocol.

Ventricular fibrillation (VF) is a leading immediate cause of sudden cardiac death. There is a strong association between aging and VF, although the mechanisms are unclear, limiting the availability of targeted therapeutic interventions. Here we found that the stress kinases p38γ and p38δ are activated in the ventricles of old mice and mice with genetic or drug-induced arrhythmogenic conditions. We discovered that, upon activation, p38γ and p38δ cooperatively increase the susceptibility to stress-induced VF. Mechanistically, our data indicate that activated p38γ and p38δ phosphorylate ryanodine receptor 2 (RyR2) disrupt Kv4.3 channel localization, promoting sarcoplasmic reticulum calcium leak, Ito current reduction and action potential duration prolongation. In turn, this led to aberrant intracellular calcium handling, premature ventricular complexes and enhanced susceptibility to VF. Blocking this pathway protected genetically modified animals from VF development and reduced the VF duration in aged animals. These results indicate that p38γ and p38δ are a potential therapeutic target for sustained VF prevention.

UNASSIGNED: This study involving automated external defibrillators (AEDs) in early treatment of refibrillation aims to evaluate the performance of a new shock advisory system (SAS) during chest compressions (CC) in out-of-hospital cardiac arrest (OHCA) patients.
UNASSIGNED: This work focuses on AED SAS performance as a secondary outcome of DEFI 2022 clinical prospective study, which included first-analysis shockable OHCA patients. SAS employs the Analyze Whilst Compressing (AWC) algorithm to interact with both cardiopulmonary resuscitation (CPR) and shock advice by conditional operation of two-stage ECG analysis in presence or absence of chest compressions. AWC is triggered by the first-shock recommendation. Then, after 1 min of CPR, ECG analysis during CC decides between two treatment scenarios. For patients with refibrillation, CPR is paused for immediate confirmation analysis and shock advice. For patients with non-shockable rhythms, CPR is continued for 2 min until standard analysis.
UNASSIGNED: Clinical data from 285 OHCA patients with shock recommendation at the first-analysis by AEDs (DEFIGARD TOUCH7, Schiller Médical) consisted of 576 standard analyses, 2011 analyses during CC, 577 confirmation analyses in absence of CC. Global AED SAS performance meets the standard recommendations for arrhythmia analysis sensitivity (94.9%) and specificity (>99.3%). AWC provided innovative treatment of shockable rhythms by stopping CPR earlier than 2 min in most ventricular fibrillations (92.9%), while most non-shockable patients (86.5-95.2%) benefitted from continuous CPR for at least 2 min.
UNASSIGNED: This study provides positive evidence for routine use of AEDs with AWC-integrated algorithm for ECG analysis during CPR by first-responders in early OHCA treatment.Clinical Trial Registration: Registration number: NCT04691089, trial register: ClinicalTrials.gov.

UNASSIGNED: Sustained ventricular tachycardia (VT) in cardiac amyloidosis is uncommon, and the substrate and outcomes of catheter ablation are not defined.
UNASSIGNED: We included 22 consecutive patients (mean age, 68±10 years; male sex, 91%) with cardiac amyloidosis (ATTR [transthyretin], n=16; light chain, n=6) undergoing catheter ablation for VT/ventricular fibrillation (VF) between 2013 and 2023 in a retrospective, observational, international study. The primary efficacy outcome was recurrent VT/VF during follow-up, while the primary safety end point included major procedure-related adverse events.
UNASSIGNED: The indication for ablation was drug-refractory VT in 17 patients (77%), and premature ventricular complex-initiated polymorphic VT/VF in 5 patients (23%). Catheter ablation was performed using endocardial (n=17.77%) or endo-epicardial approaches (n=5.23%). Complete endocardial electroanatomical voltage maps of the left and right ventricles were obtained in 17 (77%) and 10 (45%) patients, respectively. Each patient had evidence of low-voltage areas, most commonly involving the interventricular septum (n=16); late potentials were recorded in 16 patients (73%). A median of 1 (1-2) VT was inducible per patient; 12 of the 26 mappable VTs (46%) originated from the interventricular septum. Complete procedural success was achieved in 16 patients (73%), with 4 (18%) major procedure-related adverse events. After a median follow-up of 32 (14-42) months, sustained VT/VF recurrence was observed in 9 patients (41%); survival free from VT/VF recurrence was 56% (95% CI, 36%-86%) at 36-month follow-up, and most patients remained on antiarrhythmic drugs. A significant reduction in per patient implantable cardioverter defibrillator therapies was noted in the 6-month period after ablation (before: 6 [4-9] versus after: 0 [0-0]; P<0.001). In multivariable analysis, complete procedural success was associated with reduced risk of recurrent VT/VF (hazard ratio, 0.002; P=0.034).
UNASSIGNED: Catheter ablation can achieve control of recurrent VT/VF in more than half of patients with cardiac amyloidosis, and the reduction in VT/VF burden post-ablation may be relevant for quality of life. Septal substrate and risk of procedure-related complications challenge successful management of patients with cardiac amyloidosis and VT/VF.

BACKGROUND: We report the case of a 37-year-old male athlete, who developed during exercise atrial and ventricular arrhythmias. No structural heart disease.
RESULTS: Invasive programmed ventricular stimulation induced ventricular fibrillation. A heterozygous mutation in the CASQ2 gene (c.775G>T, p.E259X) was found.
CONCLUSIONS: The findings in our patient may suggest some increased ventricular excitability using programmed ventricular stimulation in CASQ2 polymorphic ventricular tachycardia patients.