“…Sympathetic activation by isoproterenol or epinephrine has been demonstrated to reverse the pharmacologic effects of several antiarrhythmic drugs, including verapamil, quinidine, procainamide, and flecainide 8–13 . Because amiodarone is a β‐adrenergic antagonist, 14 its electrophysiologic effects in the ventricle have been found to be more resistant to sympathetic activation than the effects of other drugs 15,16 .…”