COR LOE Recommendations I A CPR should be performed in patients in cardiac arrest according to published basic and advanced cardiovascular life support I A In patients with hemodynamically unstable VA that persist or recur after a maximal energy shock, intravenous amiodarone should be administered to attempt to achieve a stable rhythm after further CLINICAL STATEMENTS AND GUIDELINES I A Patients presenting with VA with hemodynamic instability should undergo direct current cardioversion.S6-1 S6-3 I B-NR In patients with polymorphic VT or VF with ST-elevation MI, angiography with emergency revascularization is recommended.S6-7 S6-10 I C-EO Patients with a wide-QRS tachycardia should be presumed to have VT if the diagnosis is unclear. IIa A In patients with hemodynamically stable VT, administration of intravenous procainamide can be useful to attempt to IIa B-R In patients with a witnessed cardiac arrest due to VF or polymorphic VT that is unresponsive to CPR, defibrillation, and vasopressor therapy, intravenous lidocaine can be beneficial.S6-1,S6-4,S6-5,S6-14,S6-15 IIa B-R In patients with polymorphic VT due to myocardial ischemia, intravenous beta blockers can be useful.S6-16,S6-17 IIa B-NR In patients with a recent MI who have VT/VF that repeatedly recurs despite direct current cardioversion and antiarrhythmic medications (VT/VF storm), an intravenous beta blocker can be useful.S6-17,S6-18 IIb A In patients in cardiac arrest, administration of epinephrine (1 mg every 3 to 5 minutes) during CPR may be reasonable.S6-1,S6-19 S6-24 IIb B-R In patients with hemodynamically stable VT, administration of intravenous amiodarone or sotalol may be considered to attempt to III: No Benefit A In patients with cardiac arrest, administration of high-dose epinephrine (>1 mg boluses) compared with standard doses is not III: No Benefit A In patients with refractory VF not related to torsades de pointes, administration of intravenous magnesium is not beneficial.S6- III: Harm B-R In patients with suspected AMI, prophylactic administration of lidocaine or high-dose amiodarone for the prevention of VT is III: Harm C-LD In patients with a wide QRS complex tachycardia of unknown origin, calcium channel blockers (eg, verapamil and diltiazem) are potentially harmful.S6-30,S6-31 Recommendation-Specific Supportive Text 1. 