External cardioversion of atrial fibrillation: role of paddle position on technical efficacy and energy requirements

External electrical and pharmacological cardioversion for atrial fibrillation, atrial flutter or atrial tachycardias: a network meta-analysis

BACKGROUND

Atrial fibrillation (AF) is the most frequent sustained arrhythmia. Cardioversion is a rhythm control strategy to restore normal/sinus rhythm, and can be achieved through drugs (pharmacological) or a synchronised electric shock (electrical cardioversion).

OBJECTIVES

To assess the efficacy and safety of pharmacological and electrical cardioversion for atrial fibrillation (AF), atrial flutter and atrial tachycardias.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Conference Proceedings Citation Index-Science (CPCI-S) and three trials registers (ClinicalTrials.gov, WHO ICTRP and ISRCTN) on 14 February 2023.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) at the individual patient level. Patient populations were aged ≥ 18 years with AF of any type and duration, atrial flutter or other sustained related atrial arrhythmias, not occurring as a result of reversible causes.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology to collect data and performed a network meta-analysis using the standard frequentist graph-theoretical approach using the netmeta package in R. We used GRADE to assess the quality of the evidence which we presented in our summary of findings with a judgement on certainty. We calculated differences using risk ratios (RR) and 95% confidence intervals (CI) as well as ranking treatments using a P value. We assessed clinical and statistical heterogeneity and split the networks for the primary outcome and acute procedural success, due to concerns about violating the transitivity assumption.

MAIN RESULTS

We included 112 RCTs (139 records), from which we pooled data from 15,968 patients. The average age ranged from 47 to 72 years and the proportion of male patients ranged from 38% to 92%. Seventy-nine trials were considered to be at high risk of bias for at least one domain, 32 had no high risk of bias domains, but had at least one domain classified as uncertain risk, and one study was considered at low risk for all domains. For paroxysmal AF (35 trials), when compared to placebo, anteroapical (AA)/anteroposterior (AP) biphasic truncated exponential waveform (BTE) cardioversion (RR: 2.42; 95% CI 1.65 to 3.56), quinidine (RR: 2.23; 95% CI 1.49 to 3.34), ibutilide (RR: 2.00; 95% CI 1.28 to 3.12), propafenone (RR: 1.98; 95% CI 1.67 to 2.34), amiodarone (RR: 1.69; 95% CI 1.42 to 2.02), sotalol (RR: 1.58; 95% CI 1.08 to 2.31) and procainamide (RR: 1.49; 95% CI 1.13 to 1.97) likely result in a large increase in maintenance of sinus rhythm until hospital discharge or end of study follow-up (certainty of evidence: moderate). The effect size was larger for AA/AP incremental and was progressively smaller for the subsequent interventions. Despite low certainty of evidence, antazoline may result in a large increase (RR: 28.60; 95% CI 1.77 to 461.30) in this outcome. Similarly, low-certainty evidence suggests a large increase in this outcome for flecainide (RR: 2.17; 95% CI 1.68 to 2.79), vernakalant (RR: 2.13; 95% CI 1.52 to 2.99), and magnesium (RR: 1.73; 95% CI 0.79 to 3.79). For persistent AF (26 trials), one network was created for electrical cardioversion and showed that, when compared to AP BTE incremental energy with patches, AP BTE maximum energy with patches (RR 1.35, 95% CI 1.17 to 1.55) likely results in a large increase, and active compression AP BTE incremental energy with patches (RR: 1.14, 95% CI 1.00 to 1.131) likely results in an increase in maintenance of sinus rhythm at hospital discharge or end of study follow-up (certainty of evidence: high). Use of AP BTE incremental with paddles (RR: 1.03, 95% CI 0.98 to 1.09; certainty of evidence: low) may lead to a slight increase, and AP MDS Incremental paddles (RR: 0.95, 95% CI 0.86 to 1.05; certainty of evidence: low) may lead to a slight decrease in efficacy. On the other hand, AP MDS incremental energy using patches (RR: 0.78, 95% CI 0.70 to 0.87), AA RBW incremental energy with patches (RR: 0.76, 95% CI 0.66 to 0.88), AP RBW incremental energy with patches (RR: 0.76, 95% CI 0.68 to 0.86), AA MDS incremental energy with patches (RR: 0.76, 95% CI 0.67 to 0.86) and AA MDS incremental energy with paddles (RR: 0.68, 95% CI 0.53 to 0.83) probably result in a decrease in this outcome when compared to AP BTE incremental energy with patches (certainty of evidence: moderate). The network for pharmacological cardioversion showed that bepridil (RR: 2.29, 95% CI 1.26 to 4.17) and quindine (RR: 1.53, (95% CI 1.01 to 2.32) probably result in a large increase in maintenance of sinus rhythm at hospital discharge or end of study follow-up when compared to amiodarone (certainty of evidence: moderate). Dofetilide (RR: 0.79, 95% CI 0.56 to 1.44), sotalol (RR: 0.89, 95% CI 0.67 to 1.18), propafenone (RR: 0.79, 95% CI 0.50 to 1.25) and pilsicainide (RR: 0.39, 95% CI 0.02 to 7.01) may result in a reduction in this outcome when compared to amiodarone, but the certainty of evidence is low. For atrial flutter (14 trials), a network could be created only for antiarrhythmic drugs. Using placebo as the common comparator, ibutilide (RR: 21.45, 95% CI 4.41 to 104.37), propafenone (RR: 7.15, 95% CI 1.27 to 40.10), dofetilide (RR: 6.43, 95% CI 1.38 to 29.91), and sotalol (RR: 6.39, 95% CI 1.03 to 39.78) probably result in a large increase in the maintenance of sinus rhythm at hospital discharge or end of study follow-up (certainty of evidence: moderate), and procainamide (RR: 4.29, 95% CI 0.63 to 29.03), flecainide (RR 3.57, 95% CI 0.24 to 52.30) and vernakalant (RR: 1.18, 95% CI 0.05 to 27.37) may result in a large increase in maintenance of sinus rhythm at hospital discharge or end of study follow-up (certainty of evidence: low). All tested electrical cardioversion strategies for atrial flutter had very high efficacy (97.9% to 100%). The rate of mortality (14 deaths) and stroke or systemic embolism (3 events) at 30 days was extremely low. Data on quality of life were scarce and of uncertain clinical significance. No information was available regarding heart failure readmissions. Data on duration of hospitalisation was scarce, of low quality, and could not be pooled.

AUTHORS' CONCLUSIONS

Despite the low quality of evidence, this systematic review provides important information on electrical and pharmacological strategies to help patients and physicians deal with AF and atrial flutter. In the assessment of the patient comorbidity profile, antiarrhythmic drug onset of action and side effect profile versus the need for a physician with experience in sedation, or anaesthetics support for electrical cardioversion are key aspects when choosing the cardioversion method.

Antero-lateral vs. antero-posterior electrode position for cardioversion of atrial fibrillation: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Multiple randomized controlled trials (RCTs) have compared the success of antero-lateral vs. antero-posterior electrode position for cardioversion of atrial fibrillation (AF). However, due to small sample size and conflicting results of these RCTs, the optimal electrode positioning for successful cardioversion remains uncertain.

METHODS

A systematic search of MEDLINE and EMBASE was conducted. Outcomes of interest included overall success of cardioversion with restoration of sinus rhythm, 1st shock success, 2nd shock success, mean shock energy required for successful cardioversion, mean number of shocks required for successful cardioversion, success of cardioversion at high energy (> 150 J) and success of cardioversion at low energy (< 150 J). Mantel-Haenszel risk ratios (RR) with 95% confidence intervals were calculated using random-effects model.

RESULTS

A total of 14 RCTs comprising 2445 patients were included. There was no statistically significant difference between two cardioversion approaches in the overall success of cardioversion (RR 1.02; 95% CI [0.97-1.06]; p = 0.43), first shock success (RR 1.14; 95% CI [0.99-1.32]), second shock success (RR 1.08; 95% CI [0.94-1.23]), mean shock energy required (mean difference 6.49; 95% CI [-17.33-30.31], success at high energy > 150 J (RR 1.02; 95% CI [0.92-1.14] and success at low energy < 150 J (RR 1.09; 95% CI [0.97-1.22]).

CONCLUSIONS

This meta-analysis of RCTs shows no significant difference in the success of cardioversion between antero-lateral vs. antero-posterior electrode position for cardioversion of AF. Large well-conducted and adequately powered randomized clinical trials are needed to definitively address this question.

Anteriolateral versus anterior-posterior electrodes in external cardioversion of atrial fibrillation: A systematic review and meta-analysis of clinical trials

The efficacy of anteriolateral versus anterior-posterior electrode positions in the success of atrial fibrillation's (AF) electrical cardioversion is unclear. Our aim is to perform a meta-analysis to compare the success rate of both electrode positions. PUBMED, WOS, OVID, and SCOPUS were searched. Inclusion criteria were clinical trials that compared anterior-lateral with anterior-posterior electrodes in external cardioversion of AF. After the full-text screening, 11 trials were included in the analysis. The total number of patients included in the study is 1845. The pooled analysis showed a statistically significant association between anterior-lateral electrode and increased cardioversion rate of AF (odds ratio [OR] = 1.40, 95% confidence interval [CI] = 1.02-1.92, p = .04). Subgroup analysis revealed a statistically significant association between the anterior-lateral electrode and increased cardioversion rate of AF in subgroups of less than five shocks, patients with 60 years old or more and patients with left atrial (LA) diameter >45 mm (OR = 1.72, 95% CI = 1.17-2.54, p = .006), (OR = 1.73, 95% CI = 1.18-2.54, p = .005), and (OR = 1.86, 95% CI = 1.04-3.34, p = .04), respectively. Anteriolateral electrode is more effective than anterior-posterior electrode in external cardioversion of AF, particularly in patients who have received less than 5 shocks, are 60 years old or older and have a LA diameter greater than 45 mm.

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.

Anteroposterior Versus Anterolateral Electrode Position for Direct Current Cardioversion of Atrial Fibrillation: A Meta-Analysis of Randomised Controlled Trials

OBJECTIVE

Data regarding optimal electrode positioning for direct current cardioversion (DCCV) of atrial fibrillation (AF) has been inconsistent. This meta-analysis was conducted to systematically compare the efficacy of anteroposterior (AP) versus anterolateral (AL) electrode placement for DCCV of AF.

METHODS

Electronic databases were searched for randomised controlled trials (RCTs) comparing AP versus AL electrode positioning in patients undergoing DCCV for AF. Primary endpoints were first-shock success and overall DCCV success. Subgroup analysis was performed by defibrillator waveform (monophasic versus biphasic). Meta-regression analyses were performed to assess for significant moderators.

RESULTS

Twelve (12) RCTs, including a total of 2,046 patients, met inclusion criteria. Neither first-shock success (relative risk [RR] 0.92; 95% CI 0.79-1.07; p=0.28) nor overall DCCV success (RR 1.01; 95% CI 0.96-1.05; p=0.78) were significantly different with AP versus AL electrode positioning. The mean number of shocks (mean difference [MD] 0.3, 95% CI -0.4 to 0.9), energy level of first successful shock (MD 3 joules; 95% CI -20 to 27) and cumulative energy delivered (MD 39 joules; 95% CI -168 to 246) were similar in AP versus AL arms. In subgroup analysis of six RCTs using biphasic defibrillators, improvement in first-shock success (RR 0.85; 95% CI 0.69-1.03; p=0.10) and overall DCCV success (RR 0.97; 95% CI 0.93-1.01; p=0.09) with AL electrode positioning did not reach statistical significance. Meta-regression analyses identified older age, higher body mass index, and longer AF duration as significant moderators favouring AL electrode positioning.

CONCLUSIONS

Pooled analysis of randomised data overall does not show a significant difference in efficacy between AP versus AL electrode positioning. Meta-regression and subgroup analyses suggest that, in contemporary practice with use of biphasic defibrillators, there may be a subset of AF patients in whom AL electrode positioning improves efficacy of DCCV.

Feature tracking strain analysis detects the onset of regional diastolic dysfunction in territories with acute myocardial injury induced by transthoracic electrical interventions

Electric interventions are used to terminate arrhythmia. However, myocardial injury from the electrical intervention can follow unique pathways and it is unknown how this affects regional ventricular function. This study investigated the impact of transthoracic electrical shocks on systolic and diastolic myocardial deformation. Ten healthy anaesthetized female swine received five transthoracic shocks (5 × 200 J) and six controls underwent a cardiovascular magnetic resonance exam prior to and 5 h after the intervention. Serial transthoracic shocks led to a global reduction in both left (LV, - 15.6 ± 3.3% to - 13.0 ± 3.6%, p < 0.01) and right ventricular (RV, - 16.1 ± 2.3% to - 12.8 ± 4.2%, p = 0.03) peak circumferential strain as a marker of systolic function and to a decrease in LV early diastolic strain rate (1.19 ± 0.35/s to 0.95 ± 0.37/s, p = 0.02), assessed by feature tracking analysis. The extent of myocardial edema (ΔT1) was related to an aggravation of regional LV and RV diastolic dysfunction, whereas only RV systolic function was regionally associated with an increase in T1. In conclusion, serial transthoracic shocks in a healthy swine model attenuate biventricular systolic function, but it is the acute development of regional diastolic dysfunction that is associated with the onset of colocalized myocardial edema.

Anterior-Posterior versus anterior-lateral electrodes position for electrical cardioversion of atrial fibrillation: A meta-analysis of randomized controlled trials

Background

The optimal electrodes position for elective direct current (DC) cardioversion of patients with atrial fibrillation (AF) remains uncertain.

Methods

An electronic search of MEDLINE, EMBASE and COCHRANE databases was performed through March 2022 for randomized trials that examined the outcomes of anterior-posterior (AP) versus anterior-lateral (AL) electrodes position during cardioversion of (AF). The main outcome was the success rate of cardioversion. Data were pooled using random effects model.

Results

The final analysis included 10 RCTs with a total of 1677 patients. There was no difference in the rate of successful cardioversion between the AP versus AL groups (86.6 vs 87.9 %; RR 1.00; 95 % Confidence Interval (CI) 0.95 to 1.06). Subgroup analysis by the shock waveform showed no significant interaction between monophasic and biphasic waveforms (P_intercation = 0.23). meta-regression analyses showed no effect modification of primary outcome according to body mass index (p = 0.15), left atrial diameter (p = 0.64), valvular heart disease (p = 0.34), lone AF (p = 0.58), or the duration of AF (p = 0.70). There was no significant difference between the AP and AL electrode position groups in successful cardioversion at low energy (RR 0.94; 95 % CI 0.74 to 1.19), the number of the delivered shocks (standardized mean difference [SMD] −0.03; 95 % CI −0.32 to 0.26) or the mean energy of the delivered shocks (SMD −0.11 and 95 % CI −0.30 to 0.07). There was lower transthoracic impedance with AP versus AL electrode position (SMD −0.28; 95 %CI −0.47 to −0.10).

Conclusion

Meta-analysis of randomized data showed no difference between AP and AL electrode positions in the success rate of DC cardioversion of AF. Either AP or AL electrode positions should be acceptable approaches for elective DC cardioversion of patients with AF.

Efficacy of Defibrillator pads placement during ventricular arrhythmias, a before and after analysis

BACKGROUND

European resuscitation guidelines describe several acceptable placements of defibrillator pads during resuscitation of cardiac arrest. However, no clinical trial has compared defibrillation efficacy between any of the different pad placements. Houston Fire Department emergency medical system (EMS) used anterior-posterior (AP) defibrillator pad placement before becoming a study site in the circulation improving resuscitation care trial (CIRC). During CIRC, Houston Fire EMS used sternal-apical (SA) pad placement.

METHODS

Data from electronic defibrillator records was compared between a pre-CIRC dataset and patients in the CIRC trial receiving manual cardiopulmonary resuscitation (CPR). Only shocks from patients with initial ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) were included. Measured outcome was defibrillation efficacy, defined as termination of VF/VT. The general estimatingequations model was used to study the association between defibrillation efficacy rates in the AP vs SA group.

RESULTS

In the pre-CIRC dataset, 207 included patients received 1023 shocks with AP pad placement, compared with 207 patients from the CIRC trial who received 1020 shocks with SA pad placement. There was no significant difference in defibrillation efficacy between AP and SA pads placement (82.1 % vs 82.2 %, p=0.98).

CONCLUSION

No difference was observed in defibrillation efficacy between AP and SA pad placement in this study. A randomized clinical trial may be indicated.

Anterior-Lateral Versus Anterior-Posterior Electrode Position for Cardioverting Atrial Fibrillation

BACKGROUND

Smaller randomized studies have reported conflicting results regarding the optimal electrode position for cardioverting atrial fibrillation. However, anterior-posterior electrode positioning is widely used as a standard and believed to be superior to anterior-lateral electrode positioning. Therefore, we aimed to compare anterior-lateral and anterior-posterior electrode positioning for cardioverting atrial fibrillation in a multicenter randomized trial.

METHODS

In this multicenter, investigator-initiated, open-label trial, we randomly assigned patients with atrial fibrillation scheduled for elective cardioversion to either anterior-lateral or anterior-posterior electrode positioning. The primary outcome was the proportion of patients in sinus rhythm after the first shock. The secondary outcome was the proportion of patients in sinus rhythm after up to 4 shocks escalating to maximum energy. Safety outcomes were any cases of arrhythmia during or after cardioversion, skin redness, and patient-reported periprocedural pain.

RESULTS

We randomized 468 patients. The primary outcome occurred in 126 patients (54%) assigned to the anterior-lateral electrode position and in 77 patients (33%) assigned to the anterior-posterior electrode position (risk difference, 22 percentage points [95% CI, 13-30]; P<0.001). The number of patients in sinus rhythm after the final cardioversion shock was 216 (93%) assigned to anterior-lateral electrode positioning and 200 (85%) assigned to anterior-posterior electrode positioning (risk difference, 7 percentage points [95% CI, 2-12]). There were no significant differences between groups in any safety outcomes.

CONCLUSIONS

Anterior-lateral electrode positioning was more effective than anterior-posterior electrode positioning for biphasic cardioversion of atrial fibrillation. There were no significant differences in any safety outcome. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03817372.

Investigating the efficacy of chest pressure for direct current cardioversion in atrial fibrillation: a randomised control trial protocol (Pressure-AF)

INTRODUCTION

Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide. Direct current cardioversion is commonly used to restore sinus rhythm in patients with AF. Chest pressure may improve cardioversion success through decreasing transthoracic impedance and increasing cardiac energy delivery. We aim to assess the efficacy and safety of routine chest pressure with direct current cardioversion for AF.

METHODS AND ANALYSIS

Multicentre, double blind (patient and outcome assessment), randomised clinical trial based in New South Wales, Australia. Patients will be randomised 1:1 to control and interventional arms. The control group will receive four sequential biphasic shocks of 150 J, 200 J, 360 J and 360 J with chest pressure on the last shock, until cardioversion success. The intervention group will receive the same shocks with chest pressure from the first defibrillation. Pads will be placed in an anteroposterior position. Success of cardioversion will be defined as sinus rhythm at 1 min after shock. The primary outcome will be total energy provided. Secondary outcomes will be success of first shock to achieve cardioversion, transthoracic impedance and sinus rhythm at post cardioversion ECG.

ETHICS AND DISSEMINATION

Ethics approval has been confirmed at all participating sites via the Research Ethics Governance Information System. The trial has been registered on the Australia New Zealand Clinical Trials Registry (ACTRN12620001028998). De-identified patient level data will be available to reputable researchers who provide sound analysis proposals.

The Impact of Personal Thoracic Impedance on Electrical Cardioversion in Patients with Atrial Arrhythmias

Background and Objectives: Direct current cardioversion (DCCV) is a safe and useful treatment for atrial tachyarrhythmias. In the past, the energy delivered in DCCV was decided upon empirically, based only on the type of tachyarrhythmia. This conventional method does not consider individual factors and may lead to unnecessary electrical damage. Materials and Methods: We performed DCCV in patients with atrial tachyarrhythmias. The impedance and electrical current at the moment of shock were measured. The human thoracic impedance between both defibrillator patches and the electric current that was used were measured. Results: A total of 683 DCCVs were performed on 466 atrial tachyarrhythmia patients. The average impedance was 64 ± 11 Ω and the average successful current was 23 ± 6 mA. The magnitude of the electrical current that was successful depended upon the human impedance (linear regression, B = −0.266, p < 0.001) and the left atrial diameter (B = 0.092, p < 0.001). Impedance was directly proportional to body mass index (BMI) (B = 1.598, p < 0.001) and was higher in females than in males (77 ± 15 Ω vs. 63 ± 11 Ω, p < 0.001). Notably, the high-impedance (>70 Ω) group had a higher BMI (27 ± 4 kg/m² vs. 25 ± 3 kg/m², p < 0.001) and a higher proportion of females (37% vs. 9%, p < 0.001) than the low-impedance group (<70 Ω). However, thoracic impedance was not an independent predictor for successful DCCV. Conclusions: Human thoracic impedance was one of the factors that impacted the level of electrical current required for successful DCCV in patients with atrial arrhythmias. In the future, it will be helpful to consider individual predictors, such as BMI and gender, to minimize electrical damage during DCCV.

[Adult advanced life support]

These European Resuscitation Council Advanced Life Support guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

European Resuscitation Council Guidelines 2021: Adult advanced life support

These European Resuscitation Council Advanced Life Support guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

Effectiveness of dual external direct current cardioversion for initial cardioversion in atrial fibrillation

INTRODUCTION

Dual external direct current cardioversion (dual-DCCV) is a rhythm control strategy for persistent atrial fibrillation (AF), involving simultaneous delivery of two shocks from two defibrillators. The long-term effectiveness of this approach has not been studied in the biphasic cardioversion era.

METHODS

Seventy-seven consecutive patients at a single center were identified to receive dual-DCCV at the time of their initial cardioversion for AF, when maximum output standard external direct current cardioversion failed in two vectors. Logistic regression was used to analyze risk factors for dual-DCCV in a historical control group of 77 patients undergoing standard cardioversion and Cox proportional hazard models were used to compare time to AF recurrence.

RESULTS

The dual-DCCV group had a significantly larger body mass index (BMI), but similar AF duration and left atrial size as controls. Multivariable logistic regression revealed that BMI and absence of prior paroxysmal AF were risk factors for dual-DCCV (P < 0.05). There was no difference observed between dual-DCCV and control groups (adjusted hazard ratio = 0.57; P = .12) after adjusting for number of shocks and age. Transient hypoxia was the only acute complication in either group (P > .999).

CONCLUSION

Dual-DCCV appears to be a safe and effective cardioversion strategy for patients with AF. The need for dual-DCCV in the treatment of AF appears to be influenced more by body habitus than atrial substrate.

Successful External Cardioversion via Fluoroscopic Electrode Positioning in Patients with Enlarged Trans-Thoracic Diameter

BACKGROUND Atrial fibrillation is the most common cardiac arrhythmia. It increases the risk of stroke by at least five-fold and is associated with higher risk for mortality and morbidity. Therefore, prompt diagnosis and treatment is crucial. In addition to anti-coagulation therapy, electrical and pharmacological cardioversion to restore sinus rhythm remains the standard of care. The most common and effective method for electrical cardioversion is achieved with placement of electrodes in the anteroposterior position. CASE REPORT We present three cases of patients with initial unsuccessful cardioversion attempts for persistent atrial fibrillation. These patients had elevated body mass indices and large trans-thoracic diameters. Their initial external cardioversion via the conventional method was not successful for restoration of sinus rhythm. This failure may have been attributed to their body habitus. To ensure that the current would traverse through the atrial tissue, the electrode pads were applied using fluoroscopic guidance for adequate myocardial depolarization. CONCLUSIONS Optimal fluoroscopic placement of the electrode pads during external cardioversion procedure increases the odds of successful restoration of sinus rhythm when compared to the conventional method.

2016 Guidelines of the Taiwan Heart Rhythm Society and the Taiwan Society of Cardiology for the management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia. Both the incidence and prevalence of AF are increasing, and the burden of AF is becoming huge. Many innovative advances have emerged in the past decade for the diagnosis and management of AF, including a new scoring system for the prediction of stroke and bleeding events, the introduction of non-vitamin K antagonist oral anticoagulants and their special benefits in Asians, new rhythm- and rate-control concepts, optimal endpoints of rate control, upstream therapy, life-style modification to prevent AF recurrence, and new ablation techniques. The Taiwan Heart Rhythm Society and the Taiwan Society of Cardiology aimed to update the information and have appointed a jointed writing committee for new AF guidelines. The writing committee members comprehensively reviewed and summarized the literature, and completed the 2016 Guidelines of the Taiwan Heart Rhythm Society and the Taiwan Society of Cardiology for the Management of Atrial Fibrillation. This guideline presents the details of the updated recommendations, along with their background and rationale, focusing on data unique for Asians. The guidelines are not mandatory, and members of the writing committee fully realize that treatment of AF should be individualized. The physician's decision remains most important in AF management.

Efficacy of Intravenous Magnesium in Facilitating Cardioversion of Atrial Fibrillation

Background—

Low serum magnesium (Mg) levels are associated with an increased risk of atrial fibrillation. Some studies have shown a benefit of Mg in facilitating pharmacological cardioversion. The role of an intravenous infusion of Mg alone in facilitating electric cardioversion is not clear.

Methods and Results—

In a prospective, randomized, double-blind, placebo-controlled trial, we enrolled patients with atrial fibrillation who were scheduled for electric cardioversion. Patients were randomized to receive Mg or placebo before cardioversion using a step-up protocol with 75, 100, 150, and 200 J biphasic shocks. Patients with hypokalemia, hypermagnesemia, or postcardiac surgery atrial fibrillation were excluded. Patients on antiarrhythmic drugs were included as long as they were at steady state. All patients were monitored for 1 hour post procedure for the maintenance of sinus rhythm. A total of 261 patients (69% male, mean age 65.5±11.1 years) were randomized (132 and 129 patients receiving Mg and placebo, respectively). Baseline characteristics were similar between both the groups. There was no statistically significant difference in the success rate of cardioversion between the 2 groups (86.4% versus 86.0%; P =0.94), cumulative amount of energy required for successful cardioversion (123.3±55.5 versus 129.5±52.6 J; P =0.40), or the number of shocks required to convert to sinus rhythm (2.25±1.24 versus 2.41±1.22, P =0.31). No adverse events were noted in either group.

Conclusions—

In patients undergoing electric cardioversion for persistent atrial fibrillation, Mg infusion does not increase the rate of successful cardioversion.

Clinical Trial Information—

URL: https://clinicaltrials.gov . Unique identifier: NCT01597557.

Minimal energy requirement for external cardioversion and catheter ablation for long-standing persistent atrial fibrillation

BACKGROUND

The minimal energy requirement (E_min) for electrical cardioversion (ECV) reflects the atrial substrate in patients with long-standing persistent atrial fibrillation (L-PeAF), but the relationship between E_minECV and radiofrequency catheter ablation (RFCA) has not yet been studied. We hypothesize that E_minECV before ablation (E_minECVpre) predicts clinical outcome of RFCA, and that catheter ablation reduces E_minECVpost.

METHODS

We included 172 patients with L-PeAF who underwent RFCA (79.7% males, 57.5±10.0 years) due to AF recurrence after ECV with an anti-arrhythmic drug (AAD). ECV began with 70J (patch electrode on anterior-posterior position) and was serially increased to 100, 150, 200, and 250J until sinus rhythm was achieved, at an average 5.0±5.6 months before RFCA. After RFCA, ECV was repeated (ECVpost) in 42 patients with recurrent AF that was not controlled by AAD.

RESULTS

(1) During 34.8±20.0 months of follow-up after RFCA, 103 patients (59.9%) showed clinical recurrence of AF after RFCA. E_minECVpre was significantly higher in patients with recurrent AF (129.0±58.6J) than those who remained in sinus rhythm (94.2±39.4J, p<0.001). (2) E_minECVpre ≥150J (HR=3.31, 95% CI 2.18-5.03, p<0.001) and left atrial volume index (HR=1.02, 95% CI 1.00-1.04, p=0.021) were significantly associated with post-RFCA recurrence. (3) Shorter post-RFCA recurrence timing was also independently related to E_minECVpre (β=-0.147, 95% CI -0.20 to -0.09, p<0.001). (4) Among 103 patients with recurrent AF after RFCA, 42 AAD-resistant AF patients underwent ECVpost. E_minECVpost (100.9±50.8J) was significantly lower than E_minECVpre (130.0±66.1J, p=0.006).

CONCLUSIONS

Higher E_minECVpre was independently associated with clinical recurrence and earlier recurrence timing of AF after catheter ablation among patients with AAD-resistant L-PeAF. Catheter ablation for L-PeAF significantly reduces E_minECV.

Refractory Hypotension after Cardioversion in a Patient with Atrial Fibrillation and Congestive Heart Failure

A 63-year-old woman with atrial fibrillation visited our hospital due to decompensated heart failure. Because atrial fibrillation was considered a remarkable precipitating factor for heart failure, cardioversion was performed. After cardioversion, refractory hypotension and cardiopulmonary arrest occurred. An arterial blood gas analysis showed marked lactic acidosis. Chronic kidney disease, heart failure, sedatives, and hypoventilation might have contributed to refractory hypotension due to severe acidosis in this case.

Esophageal electric fields are predictive of atrial cardioversion success-a finite element analysis

BACKGROUND

Atrial fibrillation (AF) is a debilitating cardiac arrhythmia, one potential treatment of which is external cardioversion. Studies have shown external cardioversion success is affected by electrode placement and that esophageal electric fields (EEFs) during low strength shocks have the potential to be used in determining patient-specific optimal electrode placements during animal experiments. The objective of this study was to determine the relationship between EEFs and atrial defibrillation thresholds (ADFTs) during computer simulations using an anatomically realistic computer model of a human torso.

METHODS

Over 600 electrode placements were simulated during which EEFs were compared to ADFTs.

RESULTS

There was no single optimal electrode placement with multiple electrode placements resulting in similarly low ADFTs. There was over 40% difference in the ADFTs between the most and least optimal electrode configurations. There was no correlation between EEFs and ADFTs for all electrode placements, but a strong negative correlation when small shifts from clinically relevant electrode placements were performed.

CONCLUSIONS

These results suggest a small shifts protocol from clinically relevant electrode placements has the potential to increase the probability of successful cardioversion on the first shock and reduce the cumulative number of shocks and energy to which patients are exposed.

The efficacy of pad placement for electrical cardioversion of atrial fibrillation/flutter: a systematic review

OBJECTIVES

Electrical cardioversion is commonly used to treat patients with atrial fibrillation and atrial flutter to restore normal sinus rhythm. There has been considerable debate as to whether the electrode placement affects the efficacy of electrical cardioversion. The objective of this study was to examine the effectiveness of anteroposterior (A-P) versus anterolateral (A-L) electrode placement to restore normal sinus rhythm.

METHODS

A search of eight electronic databases, including Medline, EMBASE, CINAHL, and Cochrane was completed. Grey literature (hand-searching, Google, and SCOPUS) searching was also conducted. Studies were included if they were controlled clinical trials comparing the effectiveness of A-P versus A-L pad placement to restore normal sinus rhythm in adult patients with atrial fibrillation and flutter. Two independent reviewers judged study relevance, inclusion, and quality (e.g., risk of bias). Individual and pooled statistics were calculated as relative risks (RRs) with 95% confidence intervals (CIs) using a random-effects model, and heterogeneity (I(2) ) was reported.

RESULTS

From 788 citations, 13 studies were included; seven involved monophasic, five involved biphasic, and one analyzed both waveform devices. The included studies tended to report cumulative success rates to restoring normal sinus rhythm after one to five sequential shocks of increasing energy; the number of shocks and energy used differed among studies. The risk of bias of the studies was "unclear." After the first shock, pad placement was not associated with an increased likelihood of restoring normal sinus rhythm (RR = 0.88; 95% CI = 0.73 to 1.06); however, heterogeneity was high (I(2) = 63%). Subgroup comparisons revealed that the A-L position was more effective (RR = 0.77; 95% CI = 0.59 to 1.00) at restoring normal sinus rhythm when using biphasic shocks (comparison p = 0.04). Overall, the pooled results failed to identify a difference between A-P and A-L pad placement in restoring normal sinus rhythm at any time (RR = 1.00; 95% CI = 0.95 to 1.05); however, heterogeneity was high (I(2) = 61%). No significant subgroup differences were found. Side effects were reported in only three studies.

CONCLUSIONS

The published literature is restricted to persistent atrial fibrillation and atrial flutter, pad placement varied, and energy levels used were lower than currently recommended; however, the accumulated evidence suggests that electrical pad placement is not a critically important factor in successful cardioversion in atrial fibrillation and flutter (AF/AFL). A trial is urgently needed in recent-onset atrial fibrillation and atrial flutter patients using biphasic devices and high energy levels to resolve the debate.

Diabetes, Obesity and Atrial Fibrillation: Epidemiology, Mechanisms and Interventions

Body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality. Over the last few decades, we have witnessed a global rise in adult obesity of epidemic proportions. Similarly, there has been a parallel increase in the incidence of atrial fibrillation (AF), itself a significant cause of cardiovascular morbidity and mortality. This may be partly attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy, however, epidemiological studies have demonstrated an independent association between obesity, diabetes and AF, suggesting possible common pathophysiological mechanisms and risk factors. Indeed, cardiac remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction have been reported in obese and diabetic cohorts. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype, which may predispose to the development of AF. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and some of the challenges posed in the management of this high-risk group of individuals.

Obesity, diabetes and atrial fibrillation; epidemiology, mechanisms and interventions

The last few decades have witnessed a global rise in adult obesity of epidemic proportions. The potential impact of this is emphasized when one considers that body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality [1, 2]. Similarly we have witnessed a parallel rise in the incidence of atrial fibrillation (AF), the commonest sustained cardiac arrhythmia, which is also a significant cause of cardiovascular morbidity and mortality. Part of this increase is attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy and consequently the prevalence of AF. However, epidemiological studies have demonstrated an independent association between obesity and AF, possibly reflecting common pathophysiology and risk factors for both conditions. Indeed, weight gain and obesity are associated with structural and functional changes of the cardiovascular system including left atrial and ventricular remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype which may predispose to the development of AF [3]. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and the challenges posed in the management of this high-risk group of individuals.

Contemporary approach to electrical and pharmacological cardioversion of atrial fibrillation

In patients with atrial fibrillation (AF), a rhythm-control strategy may be adopted when there are unacceptable symptoms from AF, failure of rate control, and/or the presence of comorbidities, such as heart failure, that may improve with restoration of sinus rhythm. When a rhythm-control strategy is chosen and the patient is in persistent AF, cardioversion will be necessary to convert the rhythm to sinus. Patients with AF present for > 48 hours must be effectively anticoagulated both prior to and after cardioversion. With newer oral anticoagulants, achieving effective anticoagulation is faster and more reliable, with no requirement for blood test monitoring. Cardioversion can be accomplished either electrically or pharmacologically, and in some cases, electrical cardioversion may be facilitated pharmacologically. Electrical cardioversion has a higher success rate compared with pharmacological cardioversion in the short-term. Pharmacological cardioversion is usually accomplished with intravenous ibutilide, oral flecainide or propafenone, or intravenous amiodarone. Oral amiodarone and dofetilide also result in chemical cardioversion in some patients over a longer period of time. Long-term success in the maintenance of sinus rhythm post-cardioversion can be increased with the use of antiarrhythmic drugs. Alternatively, when AF is recurrent and symptomatic despite the use of antiarrhythmic drugs, catheter ablation is a reasonable option for many patients. Cardioversion may be incorporated into the management approach of persistent AF when the primary therapeutic option chosen is catheter ablation.

Prehospital Synchronized Electrical Cardioversion of a Poorly Perfused SVT Patient by Paramedics

Synchronized Direct Current Cardioversion (SDC) is an established therapy for the termination of supraventricular tachycardia (SVT – either atrio-ventricular nodal reentry tachycardia (AVNRT) or atrio-ventricular reentrant tachycardia (AVRT)) with poor perfusion. The evidence is extremely limited with regard to the safety and effectiveness of this therapy. In Australia, half of the eight ambulance services include SDC within their clinical practice guidelines for the management of poorly perfused SVT; however the degree of variation in the application of SDC across these guidelines suggests a need to quantify the practice. This case provides a previously unreported example of the safety and effectiveness of prehospital SDC for SVT (with poor perfusion precipitated by a Valsalva Maneuver) by Victorian paramedics, and discusses the available literature regarding the effectiveness and safety of this practice.

SmithG, TaylorD, MorgansA, CameronP. Prehospital synchronized electrical cardioversion of a poorly perfused SVT patient by paramedics. Prehosp Disaster Med. 2013;28(3):1-4.

Outcome of Patients Discharged after their First Detected Episode of Atrial Fibrillation

Atrial fibrillation (AF) is the most frequent supraventricular arrhythmia with an approximative prevalence of 1 % in the general population and above 6 % in the elderly. After a first AF diagnosis, the hospitalization rate is markedly increased. Management of a first AF episode is different depending on the clinical status of patients. Practical guidelines developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society are available for the management of these patients. A four-step decisional scheme must be followed in the management of a first recent AF episode: need for a short- and long-term anticoagulation, define a rythmologic strategy (rhythm or rate control), select the weapon (drug, device or ablation) and reconsider the strategy if needed. After a first uncomplicated paroxysmal AF episode, guidelines recommend that prescription of antiarrhythmics must be avoided and anticoagulation is optional. After a first persistent AF episode, guidelines recommend to either respect or reduce the arrhythmia. Prescription of antiarrhythmics and anticoagulation is also optional depending on the patient?s condition. In case of the AF reduction decision, anticoagulation must be tailored preliminary to this reduction. AF recurrence rate varies depending on the patient?s condition, and the risk of stroke assessed by the CHA₂DS₂-VASc score might be similarly considered for both paroxysmal and persistent AF.

Esophageal electric fields are predictive of atrial defibrillation thresholds

BACKGROUND

Atrial fibrillation (AF) is a common cardiac arrhythmia characterized by disorganized cardiac electrical activity. Defibrillation electrode placement has been shown to affect the amount of energy and number of shocks required to defibrillate. The objective of this study was to investigate the relationship between esophageal electric fields (EEFs) and atrial defibrillation thresholds (ADFTs) to determine the feasibility of using EEFs during a low-strength shock to predict patient-specific defibrillation electrode placements.

METHODS

AF was induced and defibrillated according to a Bayesian four-shock protocol for 12-electrode placements in six pigs. EEFs were measured during each of the four shocks of the protocol and during a 1-J shock for each electrode placement. Squared EEFs (EEF(2) s) during all shocks were compared to the ADFTs using a linear regression.

RESULTS

There was a negative relationship between EEF(2) s during the 1-J shocks and ADFTs, with median R(2) values of 0.863 and 0.840 for anterior-anterior (AA) and anterior-posterior (AP) electrode placements, respectively. There was a strong, positive relationship between applied energy and EEF(2) s, with median R(2) values of at least 0.866 for all animals. The placement with the highest EEF(2) resulted in the lowest ADFT for both AA and AP placements in four of six pigs. In the other two animals, this held for one electrode set but not both.

CONCLUSIONS

There was a strong negative relationship between EEF(2) s during 1-J shocks and ADFTs for both AA and AP electrode placements. These preliminary results suggest that using EEF(2) s to predict patient-specific electrode placements is feasible.

Comparison of antero-lateral versus antero-posterior electrode position for biphasic external cardioversion of atrial flutter

External cardioversion is an established and very important tool to terminate symptomatic atrial flutter. The superiority of the biphasic waveform has been demonstrated for atrial flutter, but whether electrode position affects the efficacy of cardioversion in this population is not known. The aim of this trial was to evaluate whether anterior-lateral (A-L) compared with anterior-posterior (A-P) electrode position improves cardioversion results. Of 130 screened patients, 96 (72 men, mean age 62 +/- 12 years) were included and randomly assigned to a cardioversion protocol with either A-L or A-P electrode position. In each group, 48 patients received sequential biphasic waveform shocks using a step-up protocol consisting of 50, 75, 100, 150, or 200 J. The mean energy (65 +/- 13 J for A-L vs 77 +/- 13 J for A-P, p = 0.001) and mean number of shocks (1.48 +/- 1.01 for A-L vs 1.96 +/- 1.00 for A-P, p = 0.001) required for successful cardioversion were significantly lower in the A-L group. The efficacy of the first shock with 50 J in the A-L electrode position (35 of 48 patients [73%]) was also highly significantly greater than the first shock with 50 J in the A-P electrode position (18 of 48 patients [36%]) (p = 0.001). In conclusion, the A-L electrode position increases efficacy and requires fewer energy and shocks in external electrical cardioversion of common atrial flutter. Therefore, A-L electrode positioning should be recommended for the external cardioversion of common atrial flutter.

Outpatient electrical cardioversion of atrial fibrillation: 8 years' experience. Analysis of shock-related arrhythmias

BACKGROUND

Outpatient electrical cardioversion (EC) of atrial fibrillation is currently the standard of care. Shock-related arrhythmias may be particularly deleterious in this setting. Preoperative identification of high-risk patients may be very useful.

METHODS

A retrospective analysis was made of 543 consecutive elective EC procedures in 457 outpatients over an 8-year period in a university cardiological institute. The protocol included adequate anticoagulation, intravenous anesthesia, direct current shock, and a direct observation after a shock to detect procedure-related complications. No patients were excluded due to severity of pathology or comorbidities. Clinical characteristics, energy delivered, medications, arrhythmic phenomena, and predictors of success and complications were analyzed.

RESULTS

Of 543 ECs performed, 88.2% restored sinus rhythm, which persisted at discharge in 83.2%. No anesthesia-related complications were detected. No thromboembolic complications were detected. Use of a biphasic cardioverter was the only predictor of success (P = 0.0001). The bradyarrhythmic complication rate was 1.5%. No ventricular arrhythmic events were detected. Atrial flutter was present in five of eight patients who developed complications versus 44 of 535 patients who had no complications (P < 0.0005), and prosthetic heart valves in four of eight complicated versus 40 of 535 uncomplicated cases (P = 0.0044). The combination of atrial flutter and prosthetic heart valve was found in four of eight complicated versus 11 of 535 uncomplicated cases (P < 0.0005).

CONCLUSION

Shock-related arrhythmias are essentially bradyarrhythmias. Atrial flutter and previous cardiac surgery identify a subgroup of patients at high risk of postshock bradyarrhythmic complications.