Up until two years ago, beta blocker use for refractory ventricular fibrillation (VFib) had only been studied in animal models with sporadic human case reports. Two studies in humans have now been published and may provide some guidance in managing this difficult-to-treat condition.
First Human Study
In 2014, Dr. Steven Smith’s (@smithECGBlog) group published a retrospective evaluation of 25 patients with refractory VFib; 6 patients received esmolol during cardiac arrest and 19 patients did not.  Comparing the patients that received esmolol to those that did not: 67% and 42% had sustained return of spontaneous circulation (ROSC); 66% and 32% survived to intensive care unit admission; 50% and 16% survived to hospital discharge; and 50% and 11% survived to discharge with a favorable neurologic outcome, respectively.
New Human Study
In the October 2016 issue of Resuscitation, a new study from the Republic of Korea evaluated a similar cohort.  41 patients were included in this single center, retrospective analysis: 16 patients received esmolol and 25 patients did not. Comparing the patients that received esmolol to those that did not: 56% vs. 16% (p = 0.007) had sustained ROSC; 56% and 16% (p = 0.007) survived to ICU admission; 19% and 8% survived to 30 days, 3 months, and 6 months (p = 0.36); and 19% and 8% had a good neurologic outcome at 30 days, 3 months, and 6 months (p = 0.36), respectively.
Application to Clinical Practice
- Both studies used similar inclusion criteria: VFib that was resistant to ≥3 defibrillations, 3 mg of epinephrine, and 300 mg of amiodarone (Lee et al added no ROSC after >10 min of CPR).
- Though there are several limitations (namely single center, retrospective cohorts with small sample sizes), both studies demonstrated the potential for esmolol to increase the chance of neurologically good outcome in patients with refractory VFib.
- Not all of the comparisons reached statistical significance (small sample sizes). However, the potential clinical significance of improved neurologically intact outcomes from a relatively benign therapy (esmolol) could be profound.
- Based on these two small data sets, it may be reasonable to consider esmolol in refractory VFib cases earlier in the resuscitation (ie, before 10 minutes of CPR has transpired and before 3 doses of epinephrine).
- Driver BE, et al. Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation. Resuscitation 2014;85(10):1337-41. PMID 25033747
- Lee YH, et al. Refractory ventricular fibrillation treated with esmolol Resuscitation 2016;107:150-5. PMID 27523955