All of the following used in the treatment of cardiac arrest following ventricular fibrillation , except

Ref Harrison 19 th ed pg 1768 Atropine is no longer considered effective for asystole or PEA, but can be used for bradyarrhythmias. External pacing devices are used to attempt to establish a regular rhythm when atropine fails for a bradyarrhythmia, but chronotropic agents given intravenously are now recognized as an equally effective alternative.