Defibrillation Strategies for Refractory Ventricular Fibrillation.

BACKGROUND: Despite advances in defibrillation technology, shock-refractory ventricular fibrillation remains common during out-of-hospital cardiac arrest. Double sequential external defibrillation (DSED; rapid sequential shocks from two defibrillators) and vector-change (VC) defibrillation (switching defibrillation pads to an anterior-posterior position) have been proposed as defibrillation strategies to improve outcomes in patients with refractory ventricular fibrillation. METHODS: We conducted a cluster-randomized trial with crossover among six Canadian paramedic services to evaluate DSED and VC defibrillation as compared with standard defibrillation in adult patients with refractory ventricular fibrillation during out-of-hospital cardiac arrest. Patients were treated with one of these three techniques according to the strategy that was randomly assigned to the paramedic service. The primary outcome was survival to hospital discharge. Secondary outcomes included termination of ventricular fibrillation, return of spontaneous circulation, and a good neurologic outcome, defined as a modified Rankin scale score of 2 or lower (indicating no symptoms to slight disability) at hospital discharge. RESULTS: A total of 405 patients were enrolled before the data and safety monitoring board stopped the trial because of the coronavirus disease 2019 pandemic. A total of 136 patients (33.6%) were assigned to receive standard defibrillation, 144 (35.6%) to receive VC defibrillation, and 125 (30.9%) to receive DSED. Survival to hospital discharge was more common in the DSED group than in the standard group (30.4% vs. 13.3%; relative risk, 2.21; 95% confidence interval [CI], 1.33 to 3.67) and more common in the VC group than in the standard group (21.7% vs. 13.3%; relative risk, 1.71; 95% CI, 1.01 to 2.88). DSED but not VC defibrillation was associated with a higher percentage of patients having a good neurologic outcome than standard defibrillation (relative risk, 2.21 [95% CI, 1.26 to 3.88] and 1.48 [95% CI, 0.81 to 2.71], respectively). CONCLUSIONS: Among patients with refractory ventricular fibrillation, survival to hospital discharge occurred more frequently among those who received DSED or VC defibrillation than among those who received standard defibrillation. (Funded by the Heart and Stroke Foundation of Canada; DOSE VF ClinicalTrials.gov number, NCT04080986.).

Terminating spiral waves with a single designed stimulus: Teleportation as the mechanism for defibrillation.

We identify and demonstrate a universal mechanism for terminating spiral waves in excitable media using an established topological framework. This mechanism dictates whether high- or low-energy defibrillation shocks succeed or fail. Furthermore, this mechanism allows for the design of a single minimal stimulus capable of defibrillating, at any time, turbulent states driven by multiple spiral waves. We demonstrate this method in a variety of computational models of cardiac tissue ranging from simple to detailed human models. The theory described here shows how this mechanism underlies all successful defibrillation and can be used to further develop existing and future low-energy defibrillation strategies.

The design of the PRINCESS 2 trial: A randomized trial to study the impact of ultrafast hypothermia on complete neurologic recovery after out-of-hospital cardiac arrest with initial shockable rhythm.

BACKGROUND: Delayed hypothermia, initiated after hospital arrival, several hours after cardiac arrest with 8-10 hours to reach the target temperature, is likely to have limited impact on overall survival. However, the effect of ultrafast hypothermia, i.e., delivered intra-arrest or immediately after return of spontaneous circulation (ROSC), on functional neurologic outcome after out-of-hospital cardiac arrest (OHCA) is unclear. In two prior trials, prehospital trans-nasal evaporative intra-arrest cooling was safe, feasible and reduced time to target temperature compared to delayed cooling. Both studies showed trends towards improved neurologic recovery in patients with shockable rhythms. The aim of the PRINCESS2-study is to assess whether cooling, initiated either intra-arrest or immediately after ROSC, followed by in-hospital hypothermia, significantly increases survival with complete neurologic recovery as compared to standard normothermia care, in OHCA patients with shockable rhythms. METHODS/DESIGN: In this investigator-initiated, randomized, controlled trial, the emergency medical services (EMS) will randomize patients at the scene of cardiac arrest to either trans-nasal cooling within 20 minutes from EMS arrival with subsequent hypothermia at 33°C for 24 hours after hospital admission (intervention), or to standard of care with no prehospital or in-hospital cooling (control). Fever (>37,7°C) will be avoided for the first 72 hours in both groups. All patients will receive post resuscitation care and withdrawal of life support procedures according to current guidelines. Primary outcome is survival with complete neurologic recovery at 90 days, defined as modified Rankin scale (mRS) 0-1. Key secondary outcomes include survival to hospital discharge, survival at 90 days and mRS 0-3 at 90 days. In total, 1022 patients are required to detect an absolute difference of 9% (from 45 to 54%) in survival with neurologic recovery (80% power and one-sided α=0,025, ß=0,2) and assuming 2,5% lost to follow-up. Recruitment starts in Q1 2024 and we expect maximum enrolment to be achieved during Q4 2024 at 20-25 European and US sites. DISCUSSION: This trial will assess the impact of ultrafast hypothermia applied on the scene of cardiac arrest, as compared to normothermia, on 90-day survival with complete neurologic recovery in OHCA patients with initial shockable rhythm. TRIAL REGISTRATION: NCT06025123.

Hospital Variation in Epinephrine Administration Before Defibrillation for Cardiac Arrest Due to Shockable Rhythm.

OBJECTIVES: Contrary to advanced cardiac life support guidelines that recommend immediate defibrillation for shockable in-hospital cardiac arrest (IHCA), epinephrine administration before first defibrillation is common and associated with lower survival at a "patient-level." Whether this practice varies across hospitals and its association with "hospital-level" IHCA survival remains unknown. The purpose of this study was to determine hospital variation in rates of epinephrine administration before defibrillation for shockable IHCA and its association with IHCA survival. DESIGN: Observational cohort study. SETTING: Five hundred thirteen hospitals participating in the Get With The Guidelines Resuscitation Registry. PATIENTS: A total of 37,668 adult patients with IHCA due to an initial shockable rhythm from 2000 to 2019. INTERVENTIONS: Epinephrine before first defibrillation. MEASUREMENTS AND MAIN RESULTS: Using multivariable hierarchical regression, we examined hospital variation in epinephrine administration before first defibrillation and its association with hospital-level rates of risk-adjusted survival. The median hospital rate of epinephrine administration before defibrillation was 18.8%, with large variation across sites (range, 0-68.8%; median odds ratio: 1.54; 95% CI, 1.47-1.61). Major teaching status and annual IHCA volume were associated with hospital rate of epinephrine administration before defibrillation. Compared with hospitals with the lowest rate of epinephrine administration before defibrillation (Q1), there was a stepwise decline in risk-adjusted survival at hospitals with higher rates of epinephrine administration before defibrillation (Q1: 44.3%, Q2: 43.4%; Q3: 41.9%; Q4: 40.3%; p for trend < 0.001). CONCLUSIONS: Administration of epinephrine before defibrillation in shockable IHCA is common and varies markedly across U.S. hospitals. Hospital rates of epinephrine administration before defibrillation were associated with a significant stepwise decrease in hospital rates of risk-adjusted survival. Efforts to prioritize immediate defibrillation for patients with shockable IHCA and avoid early epinephrine administration are urgently needed.

Usefulness of risk scores and predictors of atrial fibrillation recurrence after elective electrical cardioversion.

INTRODUCTION: Electrical cardioversion (ECV) is a frequently used procedure for restoring sinus rhythm in atrial fibrillation (AF); however, the rate of recurrence is high. The identification of patients at high risk of recurrence could influence the decision-making process. The present study evaluates the predictive value of risk scores in atrial fibrillation recurrence after elective electrical cardioversion. METHODS: Unicentric, observational, and prospective study of adult patients who have undergone an elective ECV as rhythm control strategy between July 2017 and September 2022. RESULTS: From the 283 analyzed patients (mean age 63.95 ± 10.76212, 74.9% male); 99 had paroxysmal AF (35%) and 159 (59%) presented AF recurrence during a follow-up of 6 months. In patients with post-ECV AF recurrence, the period of time from diagnosis until the performance of the procedure was longer (393 ± 891 vs. 195 ± 527, p = .02). No paroxysmal AF (71.3% vs. 57.8%, p = .02) and LA dilatation with >40 mL/m2 (35.9% vs. 23.3%, p = .02) volumes were more frequent within these patients. AF recurrence was more frequent in patients who had previous ECV (HR = 1.32; 95% CI: 1.12-2.35; p = .01) and more than 1 shock to recover sinus rhythm (HR = 1.62; 95% CI: 1.07-1.63; p = .01). The SLAC, ALARMEc, ATLAS, and CAAP-AF scores were statistically significant, although with a moderate predictive capacity for post-ECV recurrence. CONCLUSIONS: Risk scores analyzed showed a modest value predicting AF recurrence after ECV. Previous ECV, and greater difficulty in restoring SR were independent predictors of recurrence.

Atrial Fibrillation: Common Questions and Answers About Diagnosis and Treatment.

Atrial fibrillation is a supraventricular arrhythmia that increases the risk of stroke and all-cause mortality. It is the most common cardiac dysrhythmia in adults in the primary care setting, and its prevalence increases with age. The U.S. Preventive Services Task Force concluded that there is insufficient evidence to assess the benefits and harms of screening asymptomatic adults older than 50 years for atrial fibrillation. Many patients with atrial fibrillation are asymptomatic, but symptoms can include palpitations, exertional dyspnea, fatigue, and chest pain. Diagnosis is based on history and physical examination findings and should be confirmed with 12-lead electrocardiography or other recording device. The initial evaluation should include transthoracic echocardiography; serum electrolyte levels; complete blood count; and thyroid, kidney, and liver function tests. Stroke risk should be assessed in patients with atrial fibrillation using the CHA2DS2-VASc score. Warfarin and direct oral anticoagulants reduce the risk of stroke by preventing atrial thrombus formation and subsequent cerebral or systemic emboli. Hemodynamically unstable patients, including those with decompensated heart failure, should be evaluated and treated emergently. Most hemodynamically stable patients should be treated initially with rate control and anticoagulation. Rhythm control, using medications or procedures, should be considered in patients with hemodynamic instability or in some patients based on risk factors and shared decision-making. Electrical cardioversion may be appropriate as first-line rhythm control. Conversion to sinus rhythm with catheter ablation may be considered in patients who are unable or unwilling to take rate or rhythm control medications long-term or if medications have been ineffective.

Association between basic life support and survival in sports-related sudden cardiac arrest: a meta-analysis.

AIMS: To evaluate the association of basic life support with survival after sports-related sudden cardiac arrest (SR-SCA). METHODS AND RESULTS: In this systematic review and meta-analysis, a search of several databases from each database inception to 31 July 2021 without language restrictions was conducted. Studies were considered eligible if they evaluated one of three scenarios in patients with SR-SCA: (i) bystander presence, (ii) bystander cardiopulmonary resuscitation (CPR), or (iii) bystander automated external defibrillator (AED) use and provided information on survival. Risk of bias was evaluated using Risk of Bias in Non-randomized Studies of Interventions. The primary outcome was survival at the longest follow up. The meta-analysis was conducted using the random-effects model. The Grading of Recommendations Assessment, Development, and Evaluations (GRADE) approach was used to rate certainty in the evidence. In total, 28 non-randomized studies were included. The meta-analysis showed significant benefit on survival in all three groups: bystander presence [odds ratio (OR) 2.55, 95% confidence interval (CI) 1.48-4.37; I2 = 25%; 9 studies-988 patients], bystander CPR (OR 3.84, 95% CI 2.36-6.25; I2 = 54%; 23 studies-2523 patients), and bystander AED use (OR 5.25, 95% CI 3.58-7.70; I2 = 16%; 19 studies-1227 patients). The GRADE certainty of evidence was judged to be moderate. CONCLUSION: In patients with SR-SCA, bystander presence, bystander CPR, and bystander AED use were significantly associated with survival. These results highlight the importance of witness intervention and encourage countries to develop their first aid training policy and AED installation in sport settings.

A Quantitative Assessment of Cerebral Hemodynamic Perturbations Associated with Long R-R Intervals in Atrial Fibrillation: A Pilot-Case-Based Experience.

Background and Objectives: Atrial fibrillation (AF) results in systemic hemodynamic perturbations which impact cerebral circulation, possibly contributing to the development of dementia. However, evidence documenting effects in cerebral perfusion is scarce. The aim of this study is to provide a quantitative characterization of the magnitude and time course of the cerebral hemodynamic response to the short hypotensive events associated with long R-R intervals, as detected by near-infrared spectroscopy (NIRS). Materials and Methods: Cerebral NIRS signals and arterial blood pressure were continuously recorded along with an electrocardiogram in twelve patients with AF undergoing elective electrical cardioversion (ECV). The top 0.5-2.5% longest R-R intervals during AF were identified in each patient and used as triggers to carry out the triggered averaging of hemodynamic signals. The average curves were then characterized in terms of the latency, magnitude, and duration of the observed effects, and the possible occurrence of an overshoot was also investigated. Results: The triggered averages revealed that long R-R intervals produced a significant drop in diastolic blood pressure (-13.7 ± 6.1 mmHg) associated with an immediate drop in cerebral blood volume (THI: -0.92 ± 0.46%, lasting 1.9 ± 0.8 s), followed by a longer-lasting decrease in cerebral oxygenation (TOI: -0.79 ± 0.37%, lasting 5.2 ± 0.9 s, p < 0.01). The recovery of the TOI was generally followed by an overshoot (+1.06 ± 0.12%). These effects were progressively attenuated in response to R-R intervals of a shorter duration. Conclusions: Long R-R intervals cause a detectable and consistent cerebral hemodynamic response which concerns both cerebral blood volume and oxygenation and outlasts the duration of the systemic perturbation. These effects are compatible with the activation of dynamic autoregulatory mechanisms in response to the hypotensive stimulus.

Optimizing Outcomes After Out-of-Hospital Cardiac Arrest With Innovative Approaches to Public-Access Defibrillation: A Scientific Statement From the International Liaison Committee on Resuscitation.

Out-of-hospital cardiac arrest is a global public health issue experienced by ≈3.8 million people annually. Only 8% to 12% survive to hospital discharge. Early defibrillation of shockable rhythms is associated with improved survival, but ensuring timely access to defibrillators has been a significant challenge. To date, the development of public-access defibrillation programs, involving the deployment of automated external defibrillators into the public space, has been the main strategy to address this challenge. Public-access defibrillator programs have been associated with improved outcomes for out-of-hospital cardiac arrest; however, the devices are used in <3% of episodes of out-of-hospital cardiac arrest. This scientific statement was commissioned by the International Liaison Committee on Resuscitation with 3 objectives: (1) identify known barriers to public-access defibrillator use and early defibrillation, (2) discuss established and novel strategies to address those barriers, and (3) identify high-priority knowledge gaps for future research to address. The writing group undertook systematic searches of the literature to inform this statement. Innovative strategies were identified that relate to enhanced public outreach, behavior change approaches, optimization of static public-access defibrillator deployment and housing, evolved automated external defibrillator technology and functionality, improved integration of public-access defibrillation with existing emergency dispatch protocols, and exploration of novel automated external defibrillator delivery vectors. We provide evidence- and consensus-based policy suggestions to enhance public-access defibrillation and guidance for future research in this area.

Automated external defibrillators and the link to first responder systems.

PURPOSE OF REVIEW: Automated external defibrillators are a very effective treatment to convert ventricular fibrillation (VF) in out-of-hospital cardiac arrest. The purpose of this paper is to review recent publications related to automated external defibrillators (AEDs). RECENT FINDINGS: Much of the recent research focus on ways to utilize publicly available AEDs included in different national/regional registers. More and more research present positive associations between engaging volunteers to increase the use of AEDs. There are only a few recent studies focusing on professional first responders such as fire fighters/police with mixed results. The use of unmanned aerial vehicles (drones) lacks clinical data and is therefore difficult to evaluate. On-site use of AED shows high survival rates but suffers from low incidence of out-of-hospital cardiac arrest (OHCA). SUMMARY: The use of public AEDs in OHCA are still low. Systems focusing on engaging volunteers in the cardiac arrest response have shown to be associated with higher AED usage. Dispatching drones equipped with AEDs is promising, but research lacks clinical data. On-site defibrillation is associated with high survival rates but is not available for most cardiac arrests.

Comparison of automated subcutaneous defibrillator screening between different pacing sites in cardiac pacing device carriers.

AIMS: The compatibility of cardiac pacing with the presence of a subcutaneous implantable cardioverter-defibrillator (S-ICD) has been investigated, but S-ICD screening test results have not been compared among different pacing sites. The objective was to compare S-ICD screening results among different cardiac pacing sites and to assess the electrocardiographic predictors of success. METHODS AND RESULTS: This prospective single-centre study conducted automated S-ICD screening in 102 carriers of cardiac pacing devices in conduction system (CSP), biventricular (BVP), right ventricular outflow tract (RVOT), or right ventricular apex (RVA) pacing sites. The study included 102 patients: 40 with CSP (20 left bundle pacing and 20 His bundle pacing), 21 with BVP, and 20 and 21 with RVOT and RVA pacing, respectively. The percentage of positive screenings was significantly higher for CSP (97.5%) than for the other patient groups (BVP 71.4%, RVOT 70%, and RVA 19%). In multivariate analysis, positive screening was associated with a narrower QRS (OR 0.95 [0.92-0.98] P = 0.001) and higher R/T ratio in precordial leads (1.76 [1.18-2.61]). CONCLUSION: A higher S-ICD eligibility rate of cardiac pacing device carriers was obtained in CSP than in conventional pacing (RVA or RVOT) or BVP. The presence of narrower paced QRS width and paced corrected QT interval and of higher R/T ratio in precordial and limb leads are electrocardiographic predictors of a positive response to screening.

A stepwise external cardioversion protocol for atrial fibrillation to maximize acute success rate.

AIMS: Cardioversion is a very commonly performed procedure for persistent atrial fibrillation (AF). However, there is no well-defined protocol to address failed external electrical direct current cardioversion. The aim of the study is to test the efficacy of a pre-defined stepwise cardioversion protocol for patients with persistent AF of ≤12 months. Success was the achievement of sinus rhythm. METHODS AND RESULTS: The study population included patients with persistent AF of ≤12 months duration requiring rhythm management. Patients were offered cardioversion using a pre-defined stepwise protocol using different electrode placement locations, applying compression at end of expiration, and higher energy delivered simultaneously through two defibrillators. : A total of 414 patients were included in the study, of which 362 (87.4%) required a single successful cardioversion. The remaining 52 (12.5%) patients required additional cardioversion attempts using the stepwise cardioversion protocol with an overall success rate of 99.3%. Two simultaneous defibrillators were required in 14 patients (3.4%). Patients with multiple cardioversions (13.5%) experienced more local skin irritation and pain compared with patients with single cardioversion (13.5% vs. 3.5%, P = 0.004). The predictor for the need for multiple cardioversion attempts is high body mass index, while high transthoracic impedance is associated with failed cardioversion. No major complications were observed during the study. CONCLUSION: The stepwise cardioversion protocol has a high success rate of >99% and can be safely performed in outpatient or inpatient settings.

Techniques improving electrical cardioversion success for patients with atrial fibrillation: a systematic review and meta-analysis.

AIMS: Electrical cardioversion is commonly used to restore sinus rhythm in patients with atrial fibrillation (AF), but procedural technique and clinical success vary. We sought to identify techniques associated with electrical cardioversion success for AF patients. METHODS AND RESULTS: We searched MEDLINE, EMBASE, CENTRAL, and the grey literature from inception to October 2022. We abstracted data on initial and cumulative cardioversion success. We pooled data using random-effects models. From 15 207 citations, we identified 45 randomized trials and 16 observational studies. In randomized trials, biphasic when compared with monophasic waveforms resulted in higher rates of initial [16 trials, risk ratio (RR) 1.71, 95% CI 1.29-2.28] and cumulative success (18 trials, RR 1.10, 95% CI 1.04-1.16). Fixed, high-energy (≥200 J) shocks when compared with escalating energy resulted in a higher rate of initial success (four trials, RR 1.62, 95% CI 1.33-1.98). Manual pressure when compared with no pressure resulted in higher rates of initial (two trials, RR 2.19, 95% CI 1.21-3.95) and cumulative success (two trials, RR 1.19, 95% CI 1.06-1.34). Cardioversion success did not differ significantly for other interventions, including: antero-apical/lateral vs. antero-posterior positioned pads (initial: 11 trials, RR 1.16, 95% CI 0.97-1.39; cumulative: 14 trials, RR 1.01, 95% CI 0.96-1.06); rectilinear/pulsed biphasic vs. biphasic truncated exponential waveform (initial: four trials, RR 1.11, 95% CI 0.91-1.34; cumulative: four trials, RR 0.98, 95% CI 0.89-1.08) and cathodal vs. anodal configuration (cumulative: two trials, RR 0.99, 95% CI 0.92-1.07). CONCLUSIONS: Biphasic waveforms, high-energy shocks, and manual pressure increase the success of electrical cardioversion for AF. Other interventions, especially pad positioning, require further study.

Electrical Stimulation for Low-Energy Termination of Cardiac Arrhythmias: a Review.

Cardiac arrhythmias are a leading cause of morbidity and mortality in the developed world, estimated to be responsible for hundreds of thousands of deaths annually. Our understanding of the electrophysiological mechanisms of such arrhythmias has grown since they were formally characterized in the late nineteenth century, and this has led to the development of numerous devices and therapies that have markedly improved outcomes for patients affected by such conditions. Despite these advancements, the application of a single large shock remains the clinical standard for treating deadly tachyarrhythmias. Such defibrillating shocks are undoubtedly effective in terminating such arrhythmias; however, they are applied without forewarning, contributing to the patient's stress and anxiety; they can be intensely painful; and they can have adverse psychological and physiological effects on patients. In recent years, there has been interest in developing defibrillation protocols that can terminate arrhythmias without crossing the human pain threshold for energy delivery, generally estimated to be between 0.1 and 1 J. In this article, we review existing literature on the development of such low-energy defibrillation methods and their underlying mechanisms, in an attempt to broadly describe the current landscape of these technologies.

Low-energy defibrillation using a base-apex epicardial electrode.

BACKGROUND: Current implantable cardioverter defibrillators (ICDs) require electric conduction with high voltage and high energy, which can impair cardiac function and induce another malignant arrhythmia. As a result, there has been a demand for an ICD that can effectively operate with lower energy to mitigate the risks of a strong electric shock. METHODS: A pair of sheet-shaped electrodes covering the heart were analyzed in three configurations (top-bottom, left-right, and front-back) using a heart simulator. We also varied the distance between the two electrodes (clearance) to identify the electrode shape with the lowest defibrillation threshold (DFT). We also investigated the ICD shock waveform, shock direction, and the effect of the backside insulator of the electrode. RESULTS: The DFT was high when the clearance was too small and the DFT was high even when the clearance was too large, suggesting that an optimal value clearance. The top-bottom electrodes with optimal clearance showed the lowest DFT when the biphasic shocks set the top electrode to a high potential first and then the bottom electrode was set to a high potential. An interval between a first shock waveform and a second shock waveform should be provided for low-energy defibrillation. Because the insulator prevents unnecessary current flow to the backside, the DFT of the electrodes with insulators is less than those without insulators. CONCLUSION: Painless defibrillation using sheet-shaped electrodes on the epicardium is predicated on the basis of results using a heart simulator.

External cardioversion of atrial fibrillation and flutter in patients with cardiac implantable electrical devices.

BACKGROUND: Atrial fibrillation and flutter are often treated with external electrical cardioversion (ECV) in patients with potentially electrically sensitive cardiovascular implantable electronic devices (CIED). Long-term follow-up data on contemporary CIED undergoing ECV is sparse. The aim is to investigate shock-related complications and impact on CIEDs. METHODS: All ECV procedures from 2010 to 2020 in patients with CIED performed at a tertiary university hospital were identified in the Danish National Patient Registry. Changes in device measurements after ECV were retrospectively studied and procedure-related complications were identified by review of medical records. RESULTS: We analyzed 763 ECV procedures in 372 patients, median device implant time 1.9 years. The mean age of patients was 69.9 ± 9.9 years of which 73.4% were men. We identified two cases of device programming changes and four cases of premature battery depletion (≤3 years after device implant). Minor changes in device measurements were found for impedances, sensing, and pacing thresholds. No patients died due to ECV-related device dysfunctions within the first 12 months after cardioversions. CONCLUSION: External cardioversion in patients with contemporary pacemakers and implantable cardioverter-defibrillators seems safe in the majority of patients. Clinically important changes in device function following cardioversion were rarely observed but may be critical for device function. In an observational study, causality between cardioversion and device dysfunction cannot be established. For patient safety, we suggest that routine device interrogation after cardioversion still should be part of standard care.

Defibrillation strategies for refractory ventricular fibrillation out-of-hospital cardiac arrest: A systematic review and network meta-analysis.

BACKGROUND AND OBJECTIVE: Double sequential external defibrillation (DSED) and vector-change defibrillation (VCD) have been suggested to enhance clinical outcomes for patients with ventricular fibrillation (VF) refractory of standard defibrillation (SD). Therefore, this network meta-analysis aims to evaluate the comparative efficacy of DSED, VCD, and SD for refractory VF. METHODS: A systematic review and network meta-analysis synthesizing randomized controlled trials (RCTs) and comparative observational studies retrieved from PubMed, EMBASE, WOS, SCOPUS, and Cochrane through November 15th, 2022. R software netmeta and netrank package (R version 4.2.0) and meta-insight software were used to pool dichotomous outcomes using odds ratio (OR) presented with the corresponding confidence interval (CI). Our protocol was prospectively published in PROSPERO with ID: CRD42022378533. RESULTS: We included seven studies with a total of 1632 participants. DSED was similar to SD in survival to hospital discharge (OR: 1.14 with 95% CI [0.55, 2.83]), favorable neurological outcome (modified Rankin scale ≤2 or cerebral performance category ≤2) (OR: 1.35 with 95% CI [0.46, 3.99]), and return of spontaneous circulation (ROSC) (OR: 0.81 with 95% CI [0.43; 1.5]). In addition, VCD was similar to SD in survival to hospital discharge (OR: 1.12 with 95% CI [0.27, 4.57]), favorable neurological outcome (OR: 1.01 with 95% CI [0.18, 5.75]), and ROSC (OR: 0.88 with 95% CI [0.24; 3.15]). CONCLUSION: Double sequential external defibrillation and VCD were not associated with enhanced outcomes in patients with refractory VF out-of-hospital cardiac arrest, compared to SD. However, the current evidence is still inconclusive, warranting further large-scale RCTs.

Association of Initial Pulseless Electrical Activity Heart Rate and Clinical Outcomes following Adult Non-Traumatic Out-of-Hospital Cardiac Arrest.

OBJECTIVE: Studies evaluating the prognostic value of the pulseless electrical activity (PEA) heart rate in out-of-hospital cardiac arrest (OHCA) patients have reported conflicting results. The objective of this study was to evaluate the association between the initial PEA heart rate and favorable clinical outcomes for OHCA patients. METHODS: The present post-hoc cohort study used the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registry Version 3, which included OHCA patients in seven US and three Canadian sites from April 2011 to June 2015. The primary outcome was survival to hospital discharge and the secondary outcome was survival with a good functional outcome. For the primary analysis, the patients were separated into eight groups according to their first rhythms and PEA heart rates: (1) initial PEA heart rate of 1-20 beats per minute (bpm); (2) 21-40 bpm; (3) 41-60 bpm; (4) 61-80 bpm; (5) 81-100 bpm; (6) 101-120 bpm; (7) over 120 bpm; (8) initial shockable rhythm (reference category). Multivariable logistic regression models were used to assess the associations of interest. RESULTS: We identified 17,675 patients (PEA: 7,089 [40.1%]; initial shockable rhythm: 10,797 [59.9%]). Patients with initial PEA electrical frequencies ≤100 bpm were less likely to survive to hospital discharge than patients with initial shockable rhythms (1-20 bpm: adjusted odds ratio [AOR] = 0.15 [95%CI 0.11-0.21]; 21-40 bpm: AOR = 0.21 [0.18-0.25]; 41-60 bpm: AOR = 0.30 [0.25-0.36]; 61-80 bpm: AOR = 0.37 [0.28-0.49]; 81-100 bpm: AOR = 0.55 [0.41-0.65]). However, there were no statistical outcome differences between PEA patients with initial electrical frequencies of >100 bpm and patients with initial shockable rhythms (101-120 bpm: AOR = 0.65 [95%CI 0.42-1.01]; >120 bpm: AOR = 0.72 [95%CI 0.37-1.39]). Similar results were observed for survival with good functional outcomes (101-120 bpm: AOR = 0.60 [95%CI 0.31-1.15]; >120 bpm: AOR = 1.08 [95%CI 0.50-2.28]). CONCLUSIONS: We observed a good association between higher initial PEA electrical frequency and favorable clinical outcomes for OHCA patients. As there is no significant difference in outcomes between patients with initial PEA heart rates of more than 100 bpm and those with initial shockable rhythms, we can hypothesize that these patients could be considered in the same prognostic category.

Real-world evidence for the use of subcutaneous implantable cardioverter-defibrillators in China: A single-center experience.

BACKGROUND: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) have been shown to be non-inferior to transvenous ICDs in the prevention of sudden cardiac death (SCD), but there is still a lack of evidence from clinical trials in China. We investigated whether S­ICD implantation in the Chinese population is safe and feasible and should be promoted in the future. METHODS: Consecutive patients undergoing S­ICD implantation at our center were enrolled in this retrospective study. Data were collected within the median follow-up period of 554 days. Data concerning patient selection, implantation procedures, complications, and episodes of shock were analyzed. RESULTS: In total, 70.2% of all 47 patients (median age = 39 years) were included for secondary prevention of SCD with different etiologies. Vector screening showed that 98% of patients were with > 1 appropriate vector in all postures. An intraoperative defibrillation test was not performed on six patients because of the high risk of disease deterioration, while all episodes of ventricular fibrillation induced post implantation were terminated by one shock. As expected, no severe complications (e.g., infection and device-related complications) were observed, except for one case of delayed healing of the incision. Overall, 15 patients (31.9%) experienced appropriate shocks (AS) with all episodes terminated by one shock. Two patients (4.3%) experienced inappropriate shocks (IAS) due to noise oversensing, resulting in a high Kaplan-Meier IAS-free rate of 95.7%. CONCLUSION: Based on appropriate patient selection and standardized implantation procedures, this real-world study confirmed the safety and efficacy of S­ICD in Chinese patients, indicating that it may help to promote the prevention of SCD in China.

Late recurrence of atrial fibrillation and flutter in patients referred for elective electrical cardioversion.

Aim    The primary aim was to ascertain long-term rates of atrial fibrillation (AF) recurrence in this all-comer patient population undergoing elective electrical cardioversion (DCR). Secondary aims included procedural DCR success, clinical predictors of long-term maintenance of sinus rhythm (SR) and AF related hospitalizations.Material and Methods    A retrospective cohort study was conducted. Consecutive patients (n=316) undergoing elective DCR were included.Results    Successful immediate reversion to SR was attained in 266 (84 %) of patients. 224 (84 %) patients were followed up for a median period of 3.5 years (IQR 2.7-4.3). Most patients (150 [67 %]) had recurrence of AF / flutter at a median time of 240 days. Clinical predictors of AF recurrence included a history of AF (HR 0.63, p=0.038) and a dilated left atrium (HR 4.13, p=0.048). Maintenance of SR was associated with fewer unplanned hospitalizations for AF (HR 3.25, p<0.01).Conclusion    There was high procedural success post DCR. However, long-term rates of AF recurrence were high, and AF recurrences were associated with increased hospitalizations. These findings underscore the importance of clinical vigilance and multi-modal management as part of a comprehensive and effective rhythm control strategy.