These AHA documents cover the broad expanse of clinical circumstances and con- siderations of mechanisms.S6-1,S6-37 2. Paramedic administration of amiodarone after at least 3 failed shocks and administration of epi- nephrine improved hospital admission rates when compared with placeboS6-6 or 1.5 mg/kg lido- in RCTs in adults with out-of-hospital cardiac arrest due to refractory VF or polymorphic VT, although survival to hospital discharge and survival with favorable neurologic outcome were not improved with amiodarone or lidocaine.S6-5 However, in the subset of patients with witnessed cardiac arrest due to initial shock-refractory VF or pulseless VT, survival to hospital discharge after amiodarone administration was higher than with The administration of procainamide in out-of-hospital cardiac arrest due to VF or pulse- less VT has been associated with more shocks, more pharmacologic interventions, longer resus- citation times, and lower survival.S6-38 3. VA with hemodynamic instability, including VF and pulseless monomorphic or polymorphic VT, causes loss of consciousness and leads to death if untreated. A short time to direct current car- dioversion is the major determinant of sur- vival, and defibrillation should be performed as quickly as possible. CPR is used until a perfusing rhythm is restored. If defibrillation is unsuccess- ful in returning spontaneous circulation, respond- ers follow advanced cardiovascular life support 4. 