CASE: A 63-year-old man has an unwitnessed cardiac arrest. EMS arrives to find him in ventricular fibrillation. They quickly begin resuscitation efforts, including defibrillation that does terminate the dysrhythmia. They give amiodarone as part of their protocol but wonder if it will make a meaningful difference.

CLINICAL QUESTION: Are adult out-of-hospital cardiac arrest (OHCA) patients with refractory ventricular fibrillation or pulseless ventricular tachycardia who receive amiodarone or lidocaine more likely to survive to hospital discharge with good neurologic outcome?

BACKGROUND: Both lidocaine and amiodarone may be considered for the treatment of ventricular fibrillation or pulseless ventricular tachycardia that is unresponsive to defibrillation.¹

There are two randomized control trials demonstrating that the use of amiodarone led to more patients with a return of spontaneous circulation at the time of hospital arrival when compared to lidocaine or placebo.^2,3 However, these early benefits did not translate into a benefit in survival to hospital discharge or neurologically intact survival.

In adult OHCA patients with refractory ventricular fibrillation or pulseless ventricular tachycardia, amiodarone or lidocaine is unlikely to provide a clinically important benefit.

REFERENCE: Kudenchuk RJ, Brown SP, Daya M, et al. Amiodarone, lidocaine, or placebo in out-of-hospital cardiac arrest. N Engl J Med. 2016;374(18):1711-1722.

• Population: Adult patients with nontraumatic OHCA and shock-refractory ventricular fibrillation or pulseless ventricular tachycardia after one or more shocks anytime during resuscitation.
  • Exclusions: Patients who had already received open-label intravenous lidocaine or amiodarone during resuscitation or had known hypersensitivity to these drugs.
• Intervention: Rapid bolus of amiodarone or lidocaine.
• Comparison: Placebo.
• Outcome:
  • Primary: Survival to hospital discharge.
  • Secondary: Favorable neurologic function at discharge (modified Rankin Scale of 3 or less).

AUTHORS’ CONCLUSIONS: Overall, neither amiodarone nor lidocaine resulted in a significantly higher rate of survival or favorable neurologic outcome than the rate with placebo among patients with OHCA due to initial shock-refractory ventricular fibrillation or pulseless ventricular tachycardia.

KEY RESULTS: There were 7,051/37,889 (18.6 percent) of patients with nontraumatic OHCA that had shock-refractory ventricular fibrillation or pulseless ventricular tachycardia. The intention-to-treat population consisted of 4,653 patients, and the per-protocol population consisted of 3,026 patients.

There was no statistical difference in the primary outcome of survival to hospital (amiodarone 24.4 percent, lidocaine 23.7 percent, and placebo 21.0 percent).

• Absolute difference: amiodarone versus placebo 3.2 percent (95 percent CI, -0.4 to 7.0; P=0.08)
• Absolute difference: lidocaine versus placebo 2.6 percent (95 percent CI, -1.0 to 6.3; P=0.16)

There was also no statistical difference in the secondary outcome of favorable neurologic function at discharge (amiodarone 18.8 percent, lidocaine 17.5 percent, and placebo 16.6 percent).