You have a patient in cardiac arrest getting high quality CPR with an initial rhythm of pulseless VT that has been defibrillated three times and received a total of 3 mg of epinephrine and a loading dose of 300 mg of amiodarone. As you continue ACLS, the patient remains in VT. Are there alternative treatments to consider? 

The 2015 ACLS guidelines recommend high quality CPR, defibrillation, followed by epinephrine every 3 to 5 minutes, and amiodarone or lidocaine for refractory VF/VT (1). Refractory VF/VT, also known as electrical storm, refers to three or more episodes of sustained VT or VF within 24 hours. This definition is a consensus among the experts as what constitutes electrical storm is being continuously debated (2,3). 

Refractory VF/VT induces myocardial ischemia, worsens oxygen-demand mismatch and increases intracellular calcium. In addition, augmented sympathetic activity from endogenous and exogenous (epinephrine) catecholamines lowers the VF threshold, making it more difficult to treat (4).  

This brings us back to management of our patient with electrical storm: consider beta blockade with esmolol. 

Driver et al. conducted a retrospective review of patients with refractory VF after having received three defibrillation attempts, 3 mg of epinephrine and 300 mg of amiodarone presenting to the Hennepin County Medical Center emergency department (4). Patients either continued to receive standard ACLS or were administered a 0.5 mg/kg loading dose of esmolol followed by an infusion at 0-100 mcg/kg/min. Patients in the esmolol group had higher rates of temporary (<20 mins) and sustained ROSC (>20 mins) as well as favorable neurologic outcome defined as CPC of 1 to 2. Unfortunately, these results are not statistically significant due to the small sample size.

Another study from an emergency department in Korea by Lee et al. modeled after the Hennepin study showed a statistically significant increase in the sustained ROSC group that received esmolol (5). Survival and good neurologic outcome were also higher in the esmolol group, although these results did not reach statistical significance. 

Both studies are retrospective with small sample size, but the important takeaway is that the patients had a poor prognosis with long resuscitations and were not responding to ACLS measures at the time of esmolol loading. Patients that achieved ROSC were able to make it to definitive therapy such as emergent cardiac catheterization (4).

In summary, when you have a patient in electrical storm after multiple failed defibrillation attempts and standard ACLS, it is unlikely that you are going to break the cycle with more electricity. The physiologic changes and sympathetic drive are making it more difficult to terminate the longer the patient is in refractory VF/VT. Patients receiving esmolol in the studies described had very poor prognosis with CPR duration up to one hour without ROSC. When you have a patient in electrical storm and have exhausted the standard therapy, esmolol is an additional treatment that can be considered.

References:

1. Panchal, A., Berg, K., Kudenchuk, P., Rios, M., Hirsch, K., Link, M., Kurz, M., Chan, P., Cabañas, J., Morley, P., Hazinski, M., Donnino, M.(2018). 2018 American Heart Association Focused Update on Advanced Cardiovascular Life Support Use of Antiarrhythmic Drugs During and Immediately After Cardiac Arrest: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Circulation 138(23)
   

2.       Gao, D., Sapp, J.(2013). Electrical storm Current Opinion in Cardiology 28(1)72-79. 

3.        Nademanee, K., Taylor, R., Bailey, W., Rieders, D., Kosar, E.(2000). Treating Electrical Storm Circulation 102(7),742-747. 

4.         Driver, B., Debaty, G., Plummer, D., Smith, S.(2014). Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation Resuscitation 85(10),1337-1341. 

5.         Lee, Y., Lee, K., Min, Y., Ahn, H., Sohn, Y., Lee, W., Oh, Y., Cho, G., Seo, J., Shin, D., Park, S., Park, S.(2016). Refractory ventricular fibrillation treated with esmolol Resuscitation 107,150-155.