Treatment of prehospital refractory ventricular fibrillation with bretylium tosylate

Bretylium, a Class III Antiarrhythmic, Returns to the Market

Bretylium, with an extensive pharmacologic and medicinal history, was approved by the United States Food and Drug Administration in 1986 for "short-term prevention and treatment of ventricular fibrillation (VF) and treatment of life-threatening ventricular arrhythmias and ventricular tachycardia (VT) unresponsive to adequate doses of a first-line antiarrhythmic agent, such as lidocaine." The NDA sponsor withdrew bretylium from the market in 2011, largely due to unavailability of raw materials required for its production; prior to this, bretylium was removed from the 2000 ACLS Guidelines algorithm for VF/pulseless VT given the challenges obtaining raw materials for drug manufacture. Recently, bretylium has been reintroduced into the US market by a generic pharmaceutical company with the same indications as before. This article provides a history of the salient trials evaluating the efficacy and safety of bretylium and looks to the future as bretylium finds its place in the modern day management of ventricular arrhythmia.

What is New in Pharmacologic Therapy for Cardiac Resuscitation?

Antiarrhythmic therapy can be a critical component of cardiac resuscitation. Therapies in this area have seen little advance in the last decade. Bretylium, a very old drug, has been reintroduced for ventricular tachycardia/ventricular fibrillation (VT/VF) therapy. There are still important questions to be addressed with bretylium: when to administer (first- or second-line) and at which dose. These questions and the development of newer agents will be areas of future research.

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.

Assessment of the EMT-P Medications Used by Baltimore County Fire Department EMS Supervisors/EMT-Ps

Many authorities in EMS have cited the lack of data concerning the efficacy of medications administered by prehospital providers. This paper reports the results of a prospective assessment of the efficacy and safety of certain medications used by emergency medical technician-paramedics (EMT-Ps) in a three-tiered response system. Data were collected for six months using forms that were completed by the EMT-P at the conclusion of an incident. Medication efficacy was measured for: bretylium tosylate, 14 patients/3 conversions to a sustaining rhythm (21 %); diazepam, 20 patients/17 stopped seizing or converted to focal motor seizure (85 %); dopamine hydrochloride, 14 patients/9 experiencing increase of blood pressure (64%); furosemide, 49 patients/28 instances of decreased respiratory distress (57%); and terbutaline sulfate, 46 patients/34 instances of decreased respiratory distress (74%). Serious side effects were rare and well managed by the EMT-Ps. These data indicate that these medications are effective and safe when used in the prehospital environment. Analysis of more data from different delivery profiles is necessary prior to drawing appropriate scientific conclusions. Data collected should include patient follow-up through hospital discharge.

Prevention of Ventricular Fibrillation, Acute Myocardial Infarction (Myocardial Necrosis), Heart Failure, and Mortality by Bretylium

It is widely, but mistakenly, believed that ischemic heart disease (IsHD) and its complications are the sole and direct result of reduced coronary blood flow by obstructive coronary artery disease (CAD). However, cardiac angina, acute myocardial infarction (AMI), and sudden cardiac death (SCD) occur in 15%-20% of patients with anatomically unobstructed and grossly normal coronaries. Moreover, severe obstructive coronary disease often occurs without associated pathologic myocardiopathy or prior symptoms, ie, unexpected sudden death, silent myocardial infarction, or the insidious appearance of congestive heart failure (CHF). The fact that catecholamines explosively augment oxidative metabolism much more than cardiac work is generally underappreciated. Thus, adrenergic actions alone are likely to be more prone to cause cardiac ischemia than reduced coronary blood flow per se. The autonomic etiology of IsHD raises contradictions to the traditional concept of anatomically obstructive CAD as the lone cause of cardiac ischemia and AMI. Actually, all the signs and symptoms of IsHD reflect autonomic nervous system imbalance, particularly adrenergic hyperactivity, which may by itself cause ischemia as in rest angina. Adrenergic activity causing ischemia signals cardiac pain to pain centers via sympathetic efferent pathways and tend to induce arrhythmogenic and necrotizing ischemic actions on the cardiovascular system. This may result in ischemia induced metabolic myocardiopathy not unlike that caused by anatomic or spasmogenic coronary obstruction. The clinical study and review presented herein suggest that adrenergic hyperactivity alone without CAD can be a primary cause of IsHD. Thus, adrenergic heart disease (AdHD), or actually adrenergic cardiovascular heart disease (ACVHD), appears to be a distinct entity, most commonly but not necessarily occurring in parallel with CAD. CAD certainly contributes to vulnerability as well as the progression of IsHD. This vicious cycle, which explains the frequent parallel occurrence of arteriosclerosis and IHD, an association that appears to be linked by the same cause, comprises a common vulnerability to deleterious adrenergic actions on the myocardium, lipid metabolism, and vascular system alike, rather than viewing CAD and IsHD as having a putative cause and effect relationship as commonly thought. Adrenergic actions can also cause the abnormal lipid metabolism that is associated with CAD and IsHD by catecholamine-induced metabolic actions on lipid mobilization by activation of phospholipases. This may also be part of toxic catecholamine hypermetabolic actions by enhancing deleterious cholesterol and lipid actions in damaging coronary vessels by plaque formation as well as inducing obstructive coronary spasm and platelet aggregation. This may also cause direct toxic necrosis on the myocardium as well as atherosclerosis in blood vessels. In fact, drugs that inhibit adrenergic actions like propranolol, reserpine, and guanethidine all inhibit arteriosclerosis induced by hypercholesterolemia in experimental animals and prevent carotid vascular disease (associated with stroke) in humans. The concomitant development of myocardiopathy and coronary vascular lesions or coronary and carotid artery intimal medial thickening by catecholamine toxicity is reflected by the frequent primary presentation of patients with catecholamine-secreting pheochromocytoma with cardiovascular disease, ie, hypertension arrhythmias, AMI, SCD, CHF, and vascular disease, which represents a clear example of the primary deleterious impact of catecholamines on the entire cardiovascular system causing adrenergic cardiovascular disease. Thus, like myocardiopathy, CAD and atherosclerosis in general may be the consequences of or a complication of catecholamine actions rather than its putative cause. This report shows how prophylactic bretylium not only prevents arrhythmias but prevents myocardial necrosis, shock, CHF, maintains or restores normal contractility, and lowers mortality in AMI patients by inducing adrenergic blockade.

Do advanced cardiac life support drugs increase resuscitation rates from in-hospital cardiac arrest? The OTAC Study Group

STUDY OBJECTIVE

The benefit of Advanced Cardiac Life Support (ACLS) medications during cardiac resuscitation is uncertain. The objective of this study was to determine whether the use of these medications increased resuscitation from in-hospital cardiac arrest.

METHODS

A prospective cohort of patients undergoing cardiac arrest in 1 of 5 academic hospitals was studied. Patient and arrest factors related to resuscitation outcome were recorded. We determined the association of the administration of ACLS drugs (epinephrine, atropine, bicarbonate, calcium, lidocaine, and bretylium) with survival at 1 hour after resuscitation.

RESULTS

Seven hundred seventy-three patients underwent cardiac resuscitation, with 269 (34. 8%) surviving for 1 hour. Use of epinephrine, atropine, bicarbonate, calcium, and lidocaine was associated with a decreased chance of successful resuscitation (P <.001 for all except lidocaine, P <.01). While controlling for significant patient factors (age, gender, and previous cardiac or respiratory disease) and arrest factors (initial cardiac rhythm, and cause of arrest), multivariate logistic regression demonstrated a significant association between unsuccessful resuscitation and the use of epinephrine (odds ratio . 08 [95% confidence interval .04-.14]), atropine (.24 [.17-.35]), bicarbonate (.31 [.21-.44]), calcium (.32 [.18-.55]), and lidocaine (.48 [.33-.71]). Drug effects did not improve when patients were grouped by their initial cardiac rhythm. Cox proportional hazards models that controlled for significant confounders demonstrated that survivors were significantly less likely to receive epinephrine (P <. 001) or atropine (P <.001) throughout the arrest.

CONCLUSION

We found no association between standard ACLS medications and improved resuscitation from in-hospital cardiac arrest. Randomized clinical trials are needed to determine whether other therapies can improve resuscitation from cardiac arrest when compared with the presently used ACLS drugs.

Cardiac arrest

This article reviews the critical resuscitations necessary during prehospital and emergency department treatment of cardiac arrest. Standard therapy for cardiac arrest rhythms is presented. Novel pharmacologic agents, types of cardiopulmonary resuscitation, and circulatory-assist devices are discussed.

Antifibrillatory drugs: the case for bretylium tosylate

The preferred treatment for ventricular fibrillation (VF) refractory to maximal electrical defibrillation remains controversial, as evidenced by recent changes in the American Heart Association's treatment algorithm. To date there have been no published studies conclusively proving one mode of therapy to be superior to another. There is, however, an abundance of animal and clinical data suggesting that bretylium tosylate (BT) is the drug of choice in this setting. In animal studies BT has been shown to lower the canine defibrillation threshold, to facilitate conversion of hypothermia-induced ventricular fibrillation, and to effect spontaneous defibrillation. In 15 years of clinical use as a drug of last resort, and more recently as a first-line drug, BT has developed an impressive track record. Most of the clinical reports are uncontrolled and/or retrospective, but they share a central theme: BT is effective in the treatment of VF refractory to standard therapy. Several small studies have reported successful conversion of VF to a stable rhythm with BT after failure of standard electrical and pharmacologic therapy. Recent studies suggest that earlier use of BT may be associated with improved outcome. Finally, as in animal studies, spontaneous defibrillation has been reported. It is important to note that no drug currently used in the treatment of countershock-refractory VF has been proven effective. The use of some of these drugs is based on tradition rather than scientific evidence. The bulk of currently available scientific data indicates that BT is superior to other commonly used antiarrhythmics in the treatment of VF resistant to countershock.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of ventricular dysrhythmias in the prehospital and emergency department setting

Each year approximately 1,500,000 people experience acute myocardial infarction. About 40% of them die, half before they reach the hospital. Ventricular fibrillation (VF) is a major cause of cardiac arrest, and delay in administering antiarrhythmic agents contributes to the incidence of out-of-hospital deaths. The 3 antiarrhythmic drugs currently used by paramedics for cardiac arrest are bretylium, lidocaine, and procainamide. The early use of bretylium tosylate is stressed in Advanced Cardiac Life Support protocols because of the agent's antifibrillatory properties, that is, its ability to increase the VF threshold and to block reentry. Evidence indicates that early, aggressive use of bretylium tosylate as a first-line agent improves the likelihood of successful resuscitation. Preliminary data are presented from an ongoing comparative study of prehospital use of bretylium tosylate and lidocaine for VF. One hundred seventeen cardiac arrests have occurred, 55 of which were associated with VF and are included in the study. Resuscitation was not attempted in 3 of the 55 patients at the request of the family and physician. Of the remaining 52 patients, 17 received bretylium tosylate plus lidocaine, 12 lidocaine alone, and 7 only bretylium tosylate. There were 16 patients who did not receive medications. According to the study protocol, the choice of antiarrhythmic agents was determined by the paramedic shift during which arrest occurred. Of the 52 patients treated, 16 (30%) survived. It is too soon to draw any conclusions.