Termination Of Fibrillation Research Articles

Atrial Fibrillation Recurrence Prevention after Electrical Cardioversion in High-Risk Patients – Benefits of Non-Antiarrhythmic Drugs

Background: Recurrence prevention after Atrial Fibrillation (AF) termination by Eelectrical Cardioversion (ECV) remains challenging. Increasing attention is paid to pathophysiological effects of non-Antiarrhythmic Drugs (non-AADs), nevertheless, with heterogeneous results. Objective: We evaluated the potential benefits of different non-AADs as adjunctive therapy to Antiarrhythmic Drugs (AADs) for AF recurrence prevention after sinus rhythm restoration by ECV in high-risk patients. Methods: The study was conducted among high-risk AF patients after successful ECV. Prescription of class IC or class III AAD was required. Data were acquired in a face-to-face baseline interview and 1-, 3-, 6-, 9-, 12-month follow-up interviews. Results: 113 patients were included. Total AF recurrence rate reached 48.7%. Angiotensin-Converting Enzyme Inhibitor (ACEI) or angiotensin receptor blocker (ARB) intake, compared with non-use, demonstrated AF recurrence rate reduction by 8.5% (46.3 vs. 54.8%), with odds ratio (OR) reduced by 28.9% (OR 0.711, 95% confidence interval (CI) 0.310-1.631, p = 0.420). Among mineralocorticoid receptor antagonist (MRA) users, AF recurrence rate was reduced by 25.1% (29.6 vs. 54.7%) and OR by 65.1% (OR 0.349, 95%CI 0.138-0.884, p = 0.023). Present statin therapy reduced AF recurrence rate by 4.2% (46.8 vs. 51.0%) and OR by 15.5% (OR 0.845, 95%CI 0.402-1.774, p = 0.656). Diuretic use showed reduction of AF recurrence rate by 10.2% (41.7 vs. 51.9%) and OR by 33.9% (OR 0.661, 95%CI 0.297-1.469, p = 0.308). Conclusion: Non-AADs demonstrated practical benefits as adjunctive therapy to AADs for AF recurrence prevention after ECV in high-risk patients, with statistically significant results established for concomitant MRA intake.

Effect of Amplitude Spectral Area on Termination of Fibrillation and Outcomes in Pediatric Cardiac Arrest

BackgroundAmplitude spectral area (AMSA) predicts termination of fibrillation (TOF) with return of spontaneous circulation (ROSC) and survival in adults but has not been studied in pediatric cardiac arrest. We characterized AMSA during pediatric cardiac arrest from a Pediatric Resuscitation Quality Collaborative and hypothesized that AMSA would be associated with TOF and ROSC.Methods and ResultsChildren aged <18 years with cardiac arrest and ventricular fibrillation were studied. AMSA was calculated for 2 seconds before shock and averaged for each subject (AMSA‐avg). TOF was defined as termination of ventricular fibrillation 10 seconds after defibrillation to any non‐ventricular fibrillation rhythm. ROSC was defined as >20 minutes without chest compressions. Univariate and multivariable logistic regression analyses controlling for weight, current, and illness category were performed. Primary end points were TOF and ROSC. Secondary end points were 24‐hour survival and survival to discharge. Between 2015 and 2019, 50 children from 14 hospitals with 111 shocks were identified. In univariate analyses AMSA was not associated with TOF and AMS‐Aavg was not associated with ROSC. Multivariable logistic regression showed no association between AMSA and TOF but controlling for defibrillation average current and illness category, there was a trend to significant association between AMSA‐avg and ROSC (odds ratio, 1.10 [1.00‒1.22] P=0.058). There was no significant association between AMSA‐avg and 24‐hour survival or survival to hospital discharge.ConclusionsIn pediatric patients, AMSA was not associated with TOF, whereas AMSA‐avg had a trend to significance for association in ROSC, but not 24‐hour survival or survival to hospital discharge.RegistrationURL: https://www.clinicaltrials.gov; Unique identifier: NCT02708134.

Abstract 150: Effect of Amplitude Spectral Area on Termination of Fibrillation and Outcomes in Pediatric Cardiac Arrest

Introduction: Amplitude spectral area (AMSA) predicts termination of fibrillation (TOF) with return of spontaneous circulation (ROSC) and hospital survival in adults, but has not been studied during pediatric cardiac arrest (pCA). Hypothesis: We characterized AMSA during pCA from a pediatric resuscitation quality (pediRES-Q) collaborative and hypothesized that AMSA would be associated with TOF and ROSC. Methods: Children &lt;18 years of age with pCA and VF were studied. AMSA was measured for 2 seconds prior to each shock and also averaged for each subject (AMSA-avg). TOF was defined as termination of VF 10 secs after defibrillation (DF) to any rhythm other than VF. ROSC was defined as &gt;20 mins without chest compressions. Univariate and multivariable logistic regression analyses controlling for weight, current, and illness category (cardiac vs non-cardiac) were performed. Primary endpoints were TOF and ROSC without ECMO. Secondary endpoints were 24-hr survival and survival to hospital discharge. Results: Between 2015-2019, 50 children from 14 hospitals (median age 3.7 years [IQR 0.6, 13.1]; median weight 16.3 kgs [IQR 6.9, 37.2]; 46% male; 73% cardiac illness category) were identified. IHCA occurred in 47 children and OHCA in 3 children. We analyzed 111 shocks with median number of DFs 1.0 [IQR 1.0, 3.0], median DF energy dose 3.27 J/kg [IQR 2.65,5.01], median DF current 0.64 A/kg [IQR 0.38,0.96], median AMSA 12.21 [IQR 7.17,17.03], and median AMSA-avg 14.6 [IQR 8.6,19.2]. TOF was achieved in 72 DFs (65%), ROSC without ECMO in 31 (62%), ROC with ECMO in 11 (22%), 24-hr survival in 40 (80%), and survival to hospital discharge in 26 (52%). Weight (OR 0.91 [0.84, 0.99] P=0.025) and DF current (OR 1.44 [0.97, 2.2] P=0.07), but not AMSA, were significantly associated with TOF for the first shock. Controlling for DF current and illness category, there was a significant association between AMSA-avg (OR 1.11 [1.0, 1.24] P=0.044) and ROSC without ECMO. There was no significant association between AMSA-avg and 24-hr survival or survival to hospital discharge. Conclusions: In pediatric patients, TOF was associated with weight and DF current, but not AMSA, whereas AMSA-avg was associated with ROSC without ECMO, but not 24-hr survival or survival to hospital discharge.

Drugs in cardiac arrest: the rise and fall of antiarrhythmics

Since the publication of 2000 guidelines for resuscitation, amiodarone is considered the antiarrhythmic drug of choice for refractory ventricular fibrillation/pulseless ventricular tachycardia. However, to date there is no proven benefit in terms of neurologically intact survival to hospital discharge. A comprehensive search of the recent literature on amiodarone, nifekalant and lidocaine in cardiac arrest was performed. Amiodarone and nifekalant are superior to lidocaine with regards to the return of spontaneous circulation and survival to hospital admission. Nifekalant shows a trend towards quicker termination of ventricular fibrillation compared to amiodarone. There is great uncertainty about the efficacy of antiarrhythmics in cardiac arrest. Failure to show improvements regarding meaningful survival questions their current use and suggests the need for re-evaluating their place in cardiopulmonary resuscitation.

GW27-e0054 Outcomes of out-of-hospital cardiac arrest with initially shockable rhythm no shock is given

Prompt defibrillation is critical for termination of ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) in out-of-hospital cardiac arrest (OHCA). For ethical reasons, the real impact of not shocking OHCA patients with an initially shockable rhythm is unlikely to be investigated

THE MECHANISMS OF THE ATRIAL FIBRILLATION TERMINATION

Understanding of the mechanisms of the atrial fibrillation (AF) termination may lead to improvement of AF treatment. The aim of this study was to investigate termination of AF in humans. We studied 6 patients (48.7±2.8 years old, 1 female) with paroxysmal AF undergoing a noninvasive ECG imaging (

Abstract 12258: Out-of-hospital Cardiac Arrest With Initially Shockable Rhythm: What Are the Outcomes if No Shock is Given?

Background: Prompt defibrillation is critical for termination of ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) in out-of-hospital cardiac arrest (OHCA). For ethical reasons, the real impact of not shocking OHCA patients with a shockable rhythm is unlikely to be investigated in clinical trials and thus remains unknown. Objectives: To describe demographics, pre-hospital characteristics, interventions, and outcomes in OHCA patients with an initially shockable rhythm who did and did not get shocked in the field in DFW ROC site. Methods: We included all non-traumatic OHCA cases ≥18 years old with VF or VT as first known rhythms, who were treated and transported to a hospital within the DFW ROC site between 2006 - 2011. We report return of spontaneous circulation (ROSC) in the field and survival to hospital discharge for victims with and without shock delivered in the field. Multiple variable regression analysis assessed the association between shock delivery and ROSC in the field as well as survival. Results: Included were 882 adult non-traumatic OHCA cases with VF or VT as first known rhythms; mean (±SD) age was 60 ± 15 years, 71% male, bystander witnessed 56%, bystander resuscitation attempt 43%, public arrest location 26%, EMS response time 4.7 ± 2.3 min, 26.9% (237) had ROSC in the field, 14.9% (131) survived to hospital discharge; 93.4% (824) of all patients were shocked, while 6.6% (58) were not shocked. Of the 6.6% (58) who were not shocked, 12.1% (7) achieved ROSC in the field and 8.6% (5) survived to hospital discharge. For those not shocked in the field, the unadjusted and adjusted odds ratios for ROSC were 0.354 (95% CI 0.158-0.791, p=0.011) and 0.189 (95% CI 0.039-0.911, p=0.038), respectively; and for survival to hospital discharge they were 0.522 (95% CI 0.205-1.331, p=0.173) and 0.498 (95% CI 0.088-2.810, p=0.430), respectively. Conclusions: In the DFW ROC site, 6.6% of OHCA victims with an initially shockable rhythm did not receive a shock, which was significantly associated with decreased ROSC in the field. More patients survived who were shocked in the field, but this difference was not significant after adjustment for Utstein variables.

Pre-shock chest compression pause effects on termination of ventricular fibrillation/tachycardia and return of organized rhythm within mechanical and manual cardiopulmonary resuscitation

BackgroundShorter manual chest compression pauses prior to defibrillation attempts is reported to improve the defibrillation success rate. Mechanical load-distributing band (LDB-) CPR enables shocks without compression pause. We studied pre-shock pause and termination of ventricular fibrillation/pulseless ventricular tachycardia 5s post-shock (TOF) and return of organized rhythm (ROOR) with LDB and manual (M-) CPR. MethodsIn a secondary analysis from the Circulation Improving Resuscitation Care trial, patients with initial shockable rhythm and interpretable post-shock rhythms were included. Pre-shock rhythm, pause duration (if any), and post-shock rhythm were obtained for each shock. Associations between TOF/ROOR and pre-shock pause duration, including no pause shocks with LDB-CPR, were analyzed with Chi-square test. A p-value <0.05 was considered statistically significant. ResultsFor TOF and ROOR analyses we included 417 LDB-CPR patients with 1476 and 1438 shocks, and 495 M-CPR patients with 1839 and 1796 shocks, respectively. For first shocks with LDB-CPR, pre-shock pause was associated with TOF (p=0.049) with lowest TOF (77%) for shocks given without pre-shock compression pause. This association was not significant when all shocks were included (p=0.07) and not for ROOR. With M-CPR there were no significant associations between shock-related chest compression pause duration and TOF or ROOR. ConclusionFor first shocks with LDB-CPR, termination of fibrillation was associated with pre-shock pause duration. There was no association for the rate of return of organized rhythm. For M-CPR, where no shocks were given during continuous chest compressions, there were no associations between pre-shock pause duration and TOF or ROOR.

Select Articles Published on the Topic of Arrhythmia and Electrophysiogy in 2013

Select Articles Published on the Topic of Arrhythmia and Electrophysiogy in 2013

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Atrium-Specific Kir3.x Determines Inducibility, Dynamics, and Termination of Fibrillation by Regulating Restitution-Driven Alternans

Atrial fibrillation is the most common cardiac arrhythmia. Ventricular proarrhythmia hinders pharmacological atrial fibrillation treatment. Modulation of atrium-specific Kir3.x channels, which generate a constitutively active current (I(K,ACh-c)) after atrial remodeling, might circumvent this problem. However, it is unknown whether and how I(K,ACh-c) contributes to atrial fibrillation induction, dynamics, and termination. Therefore, we investigated the effects of I(K,ACh-c) blockade and Kir3.x downregulation on atrial fibrillation. Neonatal rat atrial cardiomyocyte cultures and intact atria were burst paced to induce reentry. To study the effects of Kir3.x on action potential characteristics and propagation patterns, cultures were treated with tertiapin or transduced with lentiviral vectors encoding Kcnj3- or Kcnj5-specific shRNAs. Kir3.1 and Kir3.4 were expressed in atrial but not in ventricular cardiomyocyte cultures. Tertiapin prolonged action potential duration (APD; 54.7±24.0 to 128.8±16.9 milliseconds; P<0.0001) in atrial cultures during reentry, indicating the presence of I(K,ACh-c). Furthermore, tertiapin decreased rotor frequency (14.4±7.4 to 6.6±2.0 Hz; P<0.05) and complexity (6.6±7.7 to 0.6±0.8 phase singularities; P<0.0001). Knockdown of Kcnj3 or Kcnj5 gave similar results. Blockade of I(K,ACh-c) prevented/terminated reentry by prolonging APD and changing APD and conduction velocity restitution slopes, thereby altering the probability of APD alternans and rotor destabilization. Whole-heart mapping experiments confirmed key findings (e.g., >50% reduction in atrial fibrillation inducibility after I(K,ACh-c) blockade). Atrium-specific Kir3.x controls the induction, dynamics, and termination of fibrillation by modulating APD and APD/conduction velocity restitution slopes in atrial tissue with I(K,ACh-c). This study provides new molecular and mechanistic insights into atrial tachyarrhythmias and identifies Kir3.x as a promising atrium-specific target for antiarrhythmic strategies.

Shock efficacy of the entirely subcutaneous defibrillator for termination of spontaneous ventricular fibrillation in Brugada syndrome

Shock efficacy of the entirely subcutaneous defibrillator for termination of spontaneous ventricular fibrillation in Brugada syndrome

Spontaneous Termination of Ventricular Fibrillation in a Patient with Congenital Coronary Anomaly

Sudden death is common in patients with congenital coronary artery anomalies mainly when the left main coronary artery originates from the right coronary sinus. Ventricular fibrillation in these patients is irreversible unless defibrillation can be rapidly performed. We describe a 57-year-old male with an anomalous origin of circumflex and the left anterior descending coronary arteries from the right coronary sinus. He developed two episodes of ventricular fibrillation that terminated spontaneously, 10 hours after percutaneous revascularization of the circumflex coronary artery. Computed tomography angiography, in addition to confirming the anomalous origin of the coronary arteries, showed a muscle bridge over the midportion of the left anterior descending coronary artery. This is the first report of spontaneous termination of ventricular fibrillation in a patient with congenital anomaly of the coronary arteries.

Evaluation of Defibrillation Efficacy at Implantation is Unnecessary

Implantable defibrillator (ICD) therapy improves mortality in several subsets of patients at risk for sudden cardiac death. Defibrillation efficacy (DE) testing is routinely performed at initial ICD implantation, although it is associated with a small but finite risk of complications, including worsening heart failure, stroke, pulseless electrical activity, and death. Over the past 2 decades, several major advances have been made in ICD technology, including adjustable biphasic waveforms, active can technology, and higher output devices, which have greatly enhanced DE. Moreover, there is no data to suggest that DE testing at the time of ICD implantation predicts firstshock success for termination of ventricular tachycardia (VT) or ventricular fibrillation (VF), or improves survival. The purpose of this article is to demonstrate that the evaluation of DE at the time of initial ICD implantation is unnecessary.

Effect of Defibrillation Energy Dose During In-Hospital Pediatric Cardiac Arrest

To examine the effectiveness of initial defibrillation attempts. We hypothesized that (1) an initial shock dose of 2 ± 10 J/kg would be less effective for terminating fibrillation than suggested in published historical data and (2) a 4 J/kg shock dose would be more effective. This was a National Registry of Cardiopulmonary Resuscitation prospective, multisite, observational study of in-hospital pediatric (aged ≤18 years) ventricular fibrillation or pulseless ventricular tachycardia cardiac arrests from 2000-2008. Termination of ventricular fibrillation or pulseless ventricular tachycardia and event survival after initial shocks of 2 J/kg were compared with historic controls and a 4 J/kg shock dose. Of 266 children with 285 events, 173 of 285 (61%) survived the event and 61 of 266 (23%) survived to discharge. Termination of fibrillation after initial shock was achieved for 152 of 285 (53%) events. Termination of fibrillation with 2 ± 10 J/kg was much less frequent than that seen among historic control subjects (56% vs 91%; P < .001), but not different than 4 J/kg. Compared with 2 J/kg, an initial shock dose of 4 J/kg was associated with lower rates of return of spontaneous circulation (odds ratio: 0.41 [95% confidence interval: 0.21-0.81]) and event survival (odds ratio: 0.42 [95% confidence interval: 0.18-0.98]). The currently recommended 2 J/kg initial shock dose for in-hospital cardiac arrest was substantially less effective than previously published. A higher initial shock dose (4 J/kg) was not associated with superior termination of ventricular fibrillation or pulseless ventricular tachycardia or improved survival rates. The optimal pediatric defibrillation dose remains unknown.

Clinical Significance of Inducibility Test of Atrial Fibrillation after Termination of Chronic, Persistent Atrial Fibrillation during Stepwise Approach

Background and Purpose: Atrial fibrillation (AF) termination has been used as the endpoint of catheter ablation of longstanding persistent AF (LPAF). A value of an inducibility testing after achieving AF termination as predicting clinical outcome of catheter ablation of AF is unclear. Methods: In 170 patients with LPAF (>1 year) underwent stepwise approach (pulmonary vein isolation, multiple linear ablations, defragmentation, and bidirectional block of cavotricuspid isthmus), inducibility was tested by rapid atrial pacing after AF terminated. Results: Of 170 patients, induced AF (>5 minutes) in 61 patients (group 1), induced atrial tachycardia (AT) (>10 minutes) (group 2) in 72 and no induction of AF and AT (group 3) in 37. During 39±21 months of follow up, AF recurrence rate in group 1 (n=29, 48%) was similar to that in group 2 (n=34, 35%), however, higher than that in group 3 (n=10, 27%, p<0.05). Conclusion: Noninducibility of AF and AT after termination of LPAF during biatrial ablation led to a better outcome during the follow-up period.

Isoproterenol as an adjunct for treatment of idiopathic ventricular fibrillation storm in a pregnant woman

Idiopathic ventricular fibrillation is a rare entity seen in a very small subset of patients presenting to the emergency department. Management of ventricular arrhythmias in pregnant women is similar to that in nonpregnant women, but special consideration is given to avoid adverse fetal effects when selecting antiarrhythmic agents. Electrical defibrillation is the intervention of choice in both pregnant and nonpregnant patients with ventricular fibrillation of all etiologies. This was not associated with any significant adverse effects for mother or fetus. Although lidocaine and sotalol are Food and Drug Administration category B antiarrhythmics used in pregnancy, Food and Drug Administration category C antiarrhythmics such as β-blockers and category D drugs such as amiodarone can be used as pharmacologic adjuncts to facilitate termination of recurrent ventricular fibrillation where other agents have failed. Isoproterenol has been used to terminate recurrent ventricular fibrillation in patients with Brugada syndrome and torsades de pointes resistant to magnesium therapy. This case report describes a previously healthy 32-year-old pregnant woman with recurrent idiopathic ventricular fibrillation that failed to respond to standard therapy including electrical defibrillation, intravenous lidocaine, metoprolol, and amiodarone but eventually terminated with isoproterenol infusion.

Termination of Electrocution-Induced Ventricular Fibrillation by an Implantable Cardioverter Defibrillator

We describe a case in which an implantable cardioverter defibrillator (ICD) saved a patient's life after he tried to commit suicide by electrocuting himself. Deaths caused by electrocution are usually accidental and rarely suicidal. The amount of current flow is the most important factor in deciding the degree of electrical injury, which may range from transient muscle tremors to death. The ICD is electrically insulated from surrounding electromagnetic interference and the passage of electric current typically does not damage or reprogram the device. In our patient, electromagnetic interference caused by the electric current initially triggered the noise reversion mode, leading to asynchronous pacing. Ventricular fibrillation was detected and terminated only after the electromagnetic interference stopped, as depicted by the intracardiac electrogram. This case is the first documented example of an ICD-aborted fatal electrocution from ventricular fibrillation caused by an unnatural electrical source. (PACE 2010; 510-512).

Blood pressure and heart rate immediately after termination of short-term ventricular fibrillation

Implantable cardioverter/defibrillators (ICDs) can detect ventricular fibrillation (VF) and terminate it. For determining the optimal defibrillation threshold, ventricular fibrillation is repetitively induced and terminated with DC shocks. Depending on the protocol, several fibrillation/defibrillation sequences are mandatory before the final implantation of an ICD. This procedure provides an elegant human model of circulatory arrest and resuscitation. In anesthetized 73 patients (15 females) of on the average 60+/-11 years, the end-expiratory pressure was set to zero. Left ventricular pressure (LVP) was monitored with a microtip-catheter, central venous pressure (CVP) through a cannula which was advanced into the superior V. cava. ECG was recorded. After testing, a monoexponential function was found to best fit the time courses of LVP, CVP and heart rate. Data are mean+/-S.D. After termination of circulatory arrest, peak LVP increased with a time constant tau of 9.2+/-4.2 beats, CVP decreased with tau=2.8+/-1.5 beats, and RR-intervals decreased with tau=4.3+/-3.5 beats. Correlations between prefibrillatory values and steady-state values after termination of fibrillation were high: peak LVP: r=0.78; CVP: r=0.95; RRI: r=0.82. After DC termination of VF, the heart 'finds' relatively quickly a steady-state rhythm at the prefibrillatory level (22 beats), thereby normalizing CVP almost in parallel (14 beats). Peak LVP plateaus only after about 40 beats, although reasonable arterial pressures are reached within the first beats. Our data are limited to periods of ventricular fibrillation of no longer than 60s, which limits the generalisability to the setting of clinical cardiac arrest.

Abstract 2445: Comparison of Atrial Fibrillation Ablation Strategies for Paroxysmal patients presenting to the Electrophysiology Laboratory In atrial fibrillation

BACKGROUND : Whether different ablation strategies affect paroxysmal atrial fibrillation (AF) termination mode and long term cure is unclear. We compared the effect of different ablation strategies on the AF termination and long term success in patients with parox-AF presenting to the electrophysiology laboratory in AF. METHODS : One hundred and three (103) consecutive patients with parox-AF scheduled for AF ablation presenting in the lab in AF were selected for this study. The patients were randomized to PVAI only (35 pts) versus bi-atrial ablation of the complex fractionated atrial electrograms (CFAE defragmentation) including the coronary sinus (34 pts) versus CFAE followed by PVAI (34 pts) Modes of AF termination were: conversion to SR, organization into AT or persistence of AF requiring cardioversion following ablation. RESULTS are summarized below: There was no significant difference between the groups in term of sex, age, AF duration, LA size and EF. Follow up after a single procedure with AAD is summarized below CONCLUSION : Defragmentation alone had the smallest impact on both acute AF termination and one year follow-up cure rate. No difference in terms of acute and chronic success was seen between PVAI alone and PVAI asoociated with defragmentation. This suggests that PV isolation is critical to cure AF in paroxysmal AF and that adjunctive strategies have minimal impact on cure rate and should not be considered in all patients.