Nifekalant versus lidocaine for in-hospital shock-resistant ventricular fibrillation or tachycardia

Lidocaine as an anti-arrhythmic drug: Are there any indications left?

Lidocaine is classified as a class Ib anti-arrhythmic that blocks voltage- and pH-dependent sodium channels. It exhibits well investigated anti-arrhythmic effects and has been the anti-arrhythmic of choice for the treatment of ventricular arrhythmias for several decades. Lidocaine binds primarily to inactivated sodium channels, decreases the action potential duration, and increases the refractory period. It increases the ventricular fibrillatory threshold and can interrupt life-threatening tachycardias caused by re-entrant mechanisms, especially in ischemic tissue. Its use was pushed into the background in the era of amiodarone and modern electric device therapy. Recently, lidocaine has come back into focus for the treatment of acute sustained ventricular tachyarrhythmias. In this brief overview, we review the clinical pharmacology including possible side effects, the historical course, possible indications, and current Guideline recommendations for the use of lidocaine.

Development and Validation of a Novel Prognostic Model Predicting the Atrial Fibrillation Recurrence Risk for Persistent Atrial Fibrillation Patients Treated with Nifekalant During the First Radiofrequency Catheter Ablation

BACKGROUND

This study aimed to establish and assess a prediction model for patients with persistent atrial fibrillation (AF) treated with nifekalant during the first radiofrequency catheter ablation (RFCA).

METHODS

In this study, 244 patients with persistent AF from January 17, 2017 to December 14, 2017, formed the derivation cohort, and 205 patients with persistent AF from December 15, 2017 to October 28, 2018, constituted the validation cohort. The least absolute shrinkage and selection operator regression was used for variable screening and the multivariable Cox survival model for nomogram development. The accuracy and discriminative capability of this predictive model were assessed according to discrimination (area under the curve [AUC]) and calibration. Clinical practical value was evaluated using decision curve analysis.

RESULTS

Body mass index, AF duration, sex, left atrial diameter, and the different responses after nifekalant administration were identified as AF recurrence-associated factors, all of which were selected for the nomogram. In the development and validation cohorts, the AUC for predicting 1-year AF-free survival was 0.863 (95% confidence interval (CI) 0.801-0.926) and 0.855 (95% CI 0.782-0.929), respectively. The calibration curves showed satisfactory agreement between the actual AF-free survival and the nomogram prediction in the derivation and validation cohorts. In both groups, the prognostic score enabled stratifying the patients into different AF recurrence risk groups.

CONCLUSIONS

This predictive nomogram can serve as a quantitative tool for estimating the 1-year AF recurrence risk for patients with persistent AF treated with nifekalant during the first RFCA.

Efficacy of Nifekalant in Patients With Wolff-Parkinson-White Syndrome and Atrial Fibrillation: Electrophysiological and Clinical Findings

Background

The efficacy of nifekalant in preexcited atrial fibrillation (AF) has not been assessed.

Methods and Results

The study populations consisted of patients with sustained preexcited AF (n=51), paroxysmal supraventricular tachycardia (n=201), and persistent AF (n=87). Effects of intravenous infusion of nifekalant were assessed on electrophysiological and clinical parameters. Nifekalant prolonged the shortest preexcited R‐R, the average preexcited R‐R, and the average R‐R intervals from 290±35 to 333±44 ms, 353±49 to 443±64 ms, and 356±53 to 467±75 ms, respectively, in patients with preexcited AF (all P<0.001). Nifekalant also decreased the percentage of preexcited QRS complexes, heart rate, and increased systolic pressure (all P<0.001). Nifekalant terminated AF in 33 of 51 patients (65%). Similar effects were also observed in a subgroup of 12 patients with preexcited AF and impaired left ventricular function. In patients with paroxysmal supraventricular tachycardia, nifekalant significantly prolonged the effective refractory period, the block cycle length of the antegrade accessory pathway, and the atrial effective refractory period (all P<0.001). Nifekalant had no effect on the effective refractory period of the antegrade atrioventricular node. Finally, in patients with persistent AF without an accessory pathway, nifekalant did not significantly decrease the ventricular rate of AF. One patient developed Torsades de Pointes. No other adverse effects were observed.

Conclusions

Nifekalant prolongs the effective refractory period of the antegrade accessory pathway and atrium without blocking antegrade conduction through the atrioventricular node, leading to slowing and/or to termination of preexcited AF. Thus, nifekalant might be an effective and a relatively safe drug in patients with preexcited AF.

Effectiveness of antiarrhythmic drugs for shockable cardiac arrest: A systematic review

PURPOSE

The purpose of this systematic review is to provide up-to-date evidence on effectiveness of antiarrhythmic drugs for shockable cardiac arrest to help inform the 2018 International Liaison Committee on Resuscitation Consensus on Science with Treatment Recommendations.

METHODS

A search was conducted in electronic databases Medline, Embase, and Cochrane Library from inception to August 15, 2017.

RESULTS

Of the 9371 citations reviewed, a total of 14 RCTs and 17 observational studies met our inclusion criteria for adult population and only 1 observational study for pediatric population. Based on RCT level evidence for adult population, none of the anti-arrhythmic drugs showed any difference in effect compared with placebo, or with other anti-arrhythmic drugs for the critical outcomes of survival to hospital discharge and discharge with good neurological function. For the outcome of return of spontaneous circulation, the results showed a significant increase for lidocaine compared with placebo (RR = 1.16; 95% CI, 1.03-1.29, p = 0.01).

CONCLUSION

The high level evidence supporting the use of antiarrhythmic drugs during CPR for shockable cardiac arrest is limited and showed no benefit for critical outcomes of survival at hospital discharge, survival with favorable neurological function and long-term survival. Future high quality research is needed to confirm these findings and also to evaluate the role of administering antiarrhythmic drugs in children with shockable cardiac arrest, and in adults immediately after ROSC.

Does Antiarrhythmic Drug During Cardiopulmonary Resuscitation Improve the One-month Survival: The SOS-KANTO 2012 Study

BACKGROUND

Antiarrhythmic drugs (AAD) are often used for fatal ventricular arrhythmias during cardiopulmonary resuscitation (CPR). However, the efficacy of initial AAD administration during CPR in improving long-term prognosis remains unknown. This study retrospectively evaluated the effect of AAD administration during CPR on 1-month prognosis in the SOS-KANTO 2012 study population.

METHODS AND RESULTS

Of the 16,164 out-of-hospital cardiac arrest cases, 1350 shock-refractory patients were included: 747 patients not administered AAD and 603 patients administered AAD. Statistical adjustment for potential selection bias was performed using propensity score matching, yielding 1162 patients of whom 792 patients were matched (396 pairs). The primary outcome was 1-month survival. The secondary outcome was the proportion of patients with favorable neurological outcome at 1 month. Logistic regression with propensity scoring demonstrated an odds ratio (OR) for 1-month survival in the AAD group of 1.92 (P < 0.01), whereas the OR for favorable neurological outcome at 1 month was 1.44 (P = 0.26).

CONCLUSIONS

Significantly greater 1-month survival was observed in the AAD group compared with the non-AAD group. However, the effect of ADD on the likelihood of a favorable neurological outcome remains unclear. The findings of the present study may indicate a requirement for future randomized controlled trials evaluating the effect of ADD administration during CPR on long-term prognosis.

Meta-analysis of the efficacies of amiodarone and nifekalant in shock-resistant ventricular fibrillation and pulseless ventricular tachycardia

Amiodarone (AMD) and nifekalant (NIF) are used in the treatment of ventricular fibrillation or tachycardia; however, only few studies have been conducted on their efficacies. Therefore, a meta-analysis was conducted. Relevant sources were identified from PubMed, Cochrane Central Register of Controlled Trials, and Igaku Chuo Zasshi. The outcomes were short-term and long-term survival in patients with shock-resistant ventricular fibrillation /pulseless ventricular tachycardia. Thirty-three studies were analysed. The results showed that, compared to the control treatment, AMD did not improve short-term survival (odds ratio (OR): 1.25, 95% confidence interval (CI): 0.91-1.71) or long-term survival (OR: 1.00, 95% CI: 0.63-1.57). However, compared to the control treatment, NIF significantly improved short-term survival (OR: 3.23, 95% CI: 2.21-4.72) and long-term survival (OR: 1.88, 95% CI: 1.36-2.59). No significant difference was observed in short-term survival (OR: 0.85, 95% CI: 0.63-1.15) or long-term survival (OR: 1.25, 95% CI: 0.67-2.31) between AMD- and NIF-treated patients. The results suggest that NIF is beneficial for short-term and long-term survival in shock-resistant ventricular fibrillation/pulseless ventricular tachycardia; however, the efficacy of AMD in either outcome is not clear.

Nifekalant Versus Amiodarone in the Treatment of Cardiac Arrest: an Experimental Study in a Swine Model of Prolonged Ventricular Fibrillation

PURPOSE

The purpose of the experiment was to compare the effects of nifekalant and amiodarone on the return of spontaneous circulation (ROSC), survival, as well as on the hemodynamic parameters in a swine model of prolonged ventricular fibrillation (VF).

METHODS

After 8 min of untreated VF, bolus doses of epinephrine (adrenaline) and either nifekalant, or amiodarone, or saline (n = 10 per group), were administered after randomization. Cardiopulmonary resuscitation (CPR) was commenced immediately after drug administration and defibrillation was attempted 2 min later. CPR was resumed for another 2 min after each defibrillation attempt and the same dose of adrenaline was given every 4th minute during CPR.

RESULTS

Forty-eight hour survival was significantly higher with nifekalant compared to amiodarone (p < 0.001) and saline (p = 0.02), (9/10 vs. 0/10 vs. 3/10, respectively). Systolic aortic pressure, diastolic aortic pressure and coronary perfusion pressure were significantly higher with nifekalant during CPR and immediate post-resuscitation period (p < 0.05). The animals in the amiodarone group had a slower heart rate at the 1st and 45th min post-ROSC (p < 0.001 and p = 0.006, respectively). The number of electric shocks required for terminating VF, time to ROSC and adrenaline dose were significantly higher with amiodarone compared to nifekalant (p < 0.001).

CONCLUSIONS

Nifekalant showed a more favorable hemodynamic profile and improved survival compared to amiodarone and saline in this swine model.

[Drug Therapy for Shock-Resistant Ventricular Fibrillation: Comparison of Nifekalant and Amiodarone]

Early direct current (DC) shock is the most important therapy for ventricular fibrillation. Following the increased availability of automated external defibrillators (AED), the survival rate of cardiopulmonary arrest patients with ventricular fibrillation has improved. Although patients with shock-resistant ventricular fibrillation require additional antiarrhythmic drug therapy, the optimal protocol has not been established. Nifekalant is a pure potassium channel blocker with a pyrimidinedione structure. Nifekalant was approved in Japan for the treatment of life-threatening ventricular tachyarrhythmias in 1999, and is widely used as a class III antiarrhythmic intravenous drug. Intravenous amiodarone was approved in Japan in 2007, and exhibits various effects on ion channels, receptors, sympathetic activity, and thyroid function. Nifekalant and amiodarone also exhibit many pharmacological and pharmacodynamic differences. As nifekalant has no negative inotropic effect and a rapid action and clearance with a short half-life, it has some advantages over amiodarone for use in cardiopulmonary resuscitation. Indeed, data from clinical and animal studies suggest that nifekalant is superior to amiodarone for resuscitation of cardiopulmonary arrest resulting from shock-resistant ventricular fibrillation. A 300-mg bolus intravenous injection of amiodarone is considered an overdose for resuscitation of shock-resistant ventricular fibrillation. Further clinical studies are required to evaluate the effects of nifekalant compared with amiodarone, and to determine the optimal dose of amiodaone, for resuscitation of shock-resistant ventricular fibrillation.

A multicenter observational study of the effectiveness of antiarrhythmic agents in ventricular arrhythmias: A propensity-score adjusted analysis

Background

Ventricular tachyarrhythmias (VTs) are life-threatening events that result in hemodynamic compromise. Recurrence is common and may worsen a patient׳s clinical course despite appropriate treatment. This study aimed to examine the effectiveness of antiarrhythmic drugs for suppression of VTs.

Methods

In this cohort study, eligible patients were those who were admitted to one of the nine cardiovascular care centers and treated with continuous infusion of an antiarrhythmic drug for at least 1 h to prevent recurrence of VTs after return of spontaneous circulation. To adjust for differences in baseline characteristics among treatment groups, propensity scores for administered agents were generated and used as covariates in regression analyses.

Results

Seventy-two patients were enrolled and 67 patients were included in the final analysis. Amiodarone (n=21, 31.3%), nifekalant (n=24, 35.8%), and lidocaine (n=22, 32.8%) were administered as first-line therapy for suppression of VTs. In the adjusted analyses, the odds ratio (OR) of switching to a different drug was significantly higher in the lidocaine group (OR 37.6, 95% CI 5.1–279, p<0.001) than in the amiodarone group, but not in the nifekalant group (OR 4.1, 95% CI 0.72–23.2, p=0.11). There was no significant difference in mortality rate in the lidocaine group (OR 1.67, 95% CI 0.40–6.95, p=0.48) or the nifekalant group (OR 1.11, 95% CI 0.15–4.85, p=0.89) compared with the amiodarone group.

Conclusion

Amiodarone and nifekalant are similarly effective in preventing VT recurrence, but their impact on survival rate is minimal. These data indicate that both nifekalant and amiodarone can be used for treatment of refractory VT.

Comparison of nifekalant and amiodarone for resuscitation of out-of-hospital cardiopulmonary arrest resulting from shock-resistant ventricular fibrillation

Purpose

Nifekalant is a pure potassium channel blocker that has been used to treat ventricular tachyarrhythmias since 1999 in Japan. Intravenous amiodarone was approved later than nifekalant in Japan, and it is still unclear which of the two agents is superior. The aim of this study was to compare the efficacy of nifekalant and amiodarone for resuscitation of out-of-hospital cardiopulmonary arrest caused by shock-resistant ventricular fibrillation.

Methods

From December 2005 to January 2011, ambulance services transported 283 out-of-hospital cardiopulmonary arrest patients to our hospital. Of these, 25 patients were treated with nifekalant or amiodarone in response to ventricular fibrillation that was resistant to two or more shocks. We undertook a retrospective analysis of these 25 patients.

Results

We enrolled 20 men and 5 women with a mean age (± standard deviation) of 61.1 ± 16.4 years. All 25 patients were treated with tracheal intubation and intravenous epinephrine. Fourteen patients received nifekalant and 11 patients received amiodarone. The rates of return of spontaneous circulation (ROSC) (nifekalant, 5/14, versus amiodarone, 4/11; P = 0.97) and survival to discharge (nifekalant, 4/14, versus amiodarone, 2/11; P = 0.89) were not significantly different between the two groups. The time from nifekalant or amiodarone administration to ROSC was 6.0 ± 6.6 and 20.3 ± 10.0 min, respectively, which was significantly different (P < 0.05).

Conclusion

In this small sample size study, nifekalant, compared with amiodarone, is equally effective for ROSC and survival to discharge after shock-resistant ventricular fibrillation and can achieve ROSC more quickly. Further prospective studies are needed to confirm our results.

Antiarrhythmia drugs for cardiac arrest: a systemic review and meta-analysis

INTRODUCTION

Antiarrhythmia agents have been used in the treatment of cardiac arrest, and we aimed to review the relevant clinical controlled trials to assess the effects of antiarrhythmics during cardiopulmonary resuscitation.

METHODS

We searched databases including Cochrane Central Register of Controlled Trials; MEDLINE, and EMBASE. Clinical controlled trials that addressed the effects of antiarrhythmics (including amiodarone, lidocaine, magnesium, and other new potassium-channel blockers) on the outcomes of cardiac arrest were included. Data were collected independently by two authors. The risk ratio of each outcome was collected, and meta-analysis was used for data synthesis if appropriate. Heterogeneity was assessed with the χ² test and the I² test.

RESULTS

Ten randomized controlled trials and seven observational trials were identified. Amiodarone (relative risk (RR), 0.82; 95% confidence interval (CI), 0.54 to 1.24), lidocaine (RR, 2.26; 95% CI, 0.93 to 5.52), magnesium (RR, 0.82; 95% CI, 0.54 to 1.24) and nifekalant were not shown to improve the survival to hospital discharge compared with placebo, but amiodarone, lidocaine, and nifekalant were shown to be beneficial to initial resuscitation, assessed by the rate of return of spontaneous circulation and survival to hospital admission, with amiodarone being superior to lidocaine (RR, 1.28; 95% CI, 0.57 to 2.86) and nifekalant (RR, 0.50; 95% CI, 0.19 to 1.31). Bretylium and sotalol were not shown to be beneficial.

CONCLUSIONS

Our review suggests that when administered during resuscitation, antiarrhythmia agents might not improve the survival to hospital discharge, but they might be beneficial to initial resuscitation. This is consistent with the AHA 2010 guidelines for resuscitation and cardiovascular emergency, but more studies with good methodologic quality and large numbers of patients are still needed to make further assessment.

Nifekalant in the treatment of life-threatening ventricular tachyarrhythmias

The aim of the present study is to review the literature and discuss nifekalant's potential use as a first aid drug in an emergency care setting. The PubMed database was used to identify papers, using keywords nifekalant, MS-551, amiodarone and lidocaine. Nifekalant hydrochloride, formally known as MS-551, is a class III antiarrhythmic agent which acts only by increasing the time course of myocardial repolarization. It was developed and is currently being used only in Japan for the treatment of ventricular tachyarrhythmias. It is a non-selective K(+) channel blocker without any β-blocking actions. Administration of nifekalant suppressed sustained ventricular tachyarrhythmias in acute coronary syndrome patients, and in cardiac arrest victims as well as during or after cardiac surgery. The major adverse effect of nifekalant is QT interval prolongation and occurrence of torsades de pointes which requires frequent monitoring of the QT interval during nifekalant infusion with adequate dose adjustment. Nifekalant is a possible effective antiarrhythmic agent for refractory ventricular tachyarrhythmias. Further clinical studies are required before nifekalant is routinely used in the emergency care setting.

Comparative study of nifekalant versus amiodarone for shock-resistant ventricular fibrillation in out-of-hospital cardiopulmonary arrest patients

BACKGROUND

In Japan, intravenous nifekalant (NIF) was often used for direct current cardioversion-resistant ventricular fibrillation (VF), until the use of intravenous amiodarone (AMD) was approved in 2007. The defibrillatory efficacy of NIF and AMD has thus far not been compared for resuscitation.

METHODS AND RESULTS

Between August 2007 and April 2009, 403 consecutive out-of-hospital patients with cardiopulmonary arrest were transferred to the Emergency Medical Service of Tokai University. Of these, 30 patients with first defibrillation failure or VF recurrence were enrolled for this NIF/AMD study. The final defibrillation success (and hospital survival rate) was 67% (10/15) in the AMD and 47% (7/15) in the NIF group. The discharge survival rate was 53% (8/15) in the AMD and 21% (4/15) in the NIF group (P = 0.06). Notably, all 4 survivors in the NIF group could take up normal daily life again, whereas this was restricted to only 2 patients from the 11 survivors in the AMD group. The difference is probably partly attributable to longer time from AMD administration to defibrillation success compared with NIF. In the cases of defibrillation failure, VF continued in 4/8 by NIF, however, asystole or pulseless electrical activity occurred in 4/5 patients by AMD.

CONCLUSIONS

AMD may be borderline superior over NIF to facilitate defibrillation in out-of-hospital patients with cardiopulmonary arrest. However, from the view point of preservation of brain function, NIF is not inferior to AMD for CPR.

Comparison of the efficacy of nifekalant and amiodarone in a porcine model of cardiac arrest

OBJECTIVE

To compare the efficacy of nifekalant and amiodarone in the treatment of cardiac arrest in a porcine model.

METHODS

After 4min of untreated ventricular fibrillation, animals were randomly treated with nifekalant (2mgkg(-1)), amiodarone (5mgkg(-1)) or saline placebo (n=12 pigs per group). Precordial compression and ventilation were initiated after drug administration and defibrillation was attempted 2min later. Hemodynamics were continuously measured for 6h after successful resuscitation.

RESULTS

Compared with saline, nifekalant and amiodarone equally decreased the number of electric shocks, defibrillation energy, epinephrine dose, and duration of cardiopulmonary resuscitation required for successful resuscitation (P<0.01). The incidence of restoration of spontaneous circulation (ROSC) and the 24-h survival rate were higher in both antiarrhythmic drug groups (P<0.05) vs. the saline group. Furthermore, post-resuscitation myocardial dysfunction at 4-6h after successful resuscitation was improved in animals given antiarrhythmic drugs as compared with the saline group (P<0.05). There were no differences between nifekalant and amiodarone for any of these parameters.

CONCLUSION

The effect of nifekalant was similar to that of amiodarone for improving defibrillation efficacy and for the treatment of cardiac arrest. Administration of either nifekalant or amiodarone before defibrillation increased the ROSC and 24-h survival rates and improved post-resuscitation cardiac function in this porcine model.