Use of Beta-Blockers to Treat Patients with Ventricular Fibrillation

Ventricular fibrillation (VF) is the presenting cardiac rhythm in up to 40% of out-of hospital cardiac arrests. VF that does not respond to the first few defibrillation attempts is associated with high morality rates of up to 97%. ACLS guidelines recommend treating cardiac arrest patients with refractory VF with epinephrine, and amiodarone or lidocaine.  However these guidelines are often unsuccessful in achieving and maintaining return of spontaneous circulation (ROSC). Although not part of ACLS guidelines, some literature supports considering double sequence defibrillation as well as administering beta-blockers for VF refractory after standard ACLS protocol has been initiated.

Mechanism:

 

Refractory ventricular fibrillation is a severe form of electrical storm, defined as a clustering of destabilizing episodes of VF in a short period of time that does not respond to multiple defibrillation attempts. Cardiac arrest patients have high levels of catecholamines due to endogenous release and exogenous administration of epinephrine. Beneficial effects of these catecholamines are seen in the activation in of a1 receptors which cause vasoconstriction and increased coronary perfusion pressure. Adverse effects of epinephrine are seen through the activation of b1 and b2 receptors, which increase myocardial oxygen demand, worsen ischemic injury, lower VF threshold, and worsening post-resuscitation myocardial function. The use of beta-blockers is predicted to help terminate electrical storm and help prevent patients from re-entering into VF.

Evidence:

 

A small retrospective study (n=25) performed by Driver et al. (2014) demonstrated that the use of esmolol in refractory VF given after receiving at least three unsuccessful attempts at defibrillation, epinephrine 3 mg, and amiodarone 300mg. Esmolol was administered in a 500 mcg/kg bolus and followed by a drip of 0-100mcg/kg/min. Results showed that administration of esmolol was associated with higher rates of temporary ROSC, sustained ROSC, survival to hospital discharge, and discharge with favorable neurologic outcomes. Beta-blockers in refractory VF have been studied in animal and human models since the 1960’s. Though the existing literature supports a beneficial effect of beta-blockade in patients with VF/VT, high quality human trials are still lacking. Most studies have been evaluating the utility of propranolol or esmolol.

Interestingly, the ARREST and ALIVE trials showed that while amiodarone is associated with increased survival to hospital admission, it was not associated with a survival to discharge. However, in Driver et al. (2014) esmolol was associated with a survival benefit.

Conclusion:

 

            Beta-blockade should be considered in patients with refractory VF prior to the cessation of resuscitative efforts. 

References:

1.         Bourque, Daniel et al. B-Blockers for the treatment of cardiac arrest from ventricular fibrillation. Resuscitation 2007; 75:434-444.

2.        Carvalho de Oliveira, Felipe et al. Use of beta blockers for the treatement of cariac arrest due to ventricular fibrillation/pulseless ventricular tachycardia: A systemic review. Resuscitation 2012; 83: 674-683.

3.        Driver, Brian et al. Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation. Resuscitation 2014; 85: 1337-1341.