Antiarrhythmic Medication Use in Cardiac Arrest

Introduction to Guidelines

• The American Heart Association guidelines establish that amiodarone and lidocaine are alternative therapies, not complementary, for the treatment of ventricular fibrillation/pulseless ventricular tachycardia (VF/VT) refractory to shock and cardiopulmonary resuscitation (CPR) 1

Fundamentals of Clinical Guidelines

• Amiodarone may be considered for VF/VT refractory to CPR, defibrillation, and vasopressors, with a Class IIb recommendation 1
• Lidocaine may be considered as an alternative to amiodarone for the same indication, with a Class IIb recommendation 1
• The key principle is to use one or the other, never both simultaneously, due to the lack of evidence demonstrating benefit and the increased risk of adverse cardiovascular effects 2

Reasons for Not Combining Amiodarone and Lidocaine

Absence of Evidence of Benefit

• No antiarrhythmic has been shown to increase survival or improve neurological outcome after cardiac arrest 1

Risk of Toxicity

• Amiodarone can cause hypotension in approximately 16% of patients due to vasodilation 3
• Lidocaine can cause myocardial and circulatory depression, especially in patients with low cardiac output 4
• Both medications can prolong the QT interval, increasing the risk of torsades de pointes 4

Decision Algorithm During Cardiac Arrest

For VF/VT Refractory to Shock

• Step 1: High-quality CPR, defibrillation, and epinephrine 1
• Step 2: If VF/VT persists after 3 shocks and epinephrine, choose one of the following: amiodarone 300 mg IV/IO or lidocaine 1-1.5 mg/kg IV/IO 1

Safety Considerations

• Amiodarone IV requires special monitoring due to the risk of hypotension, bradycardia, and cardiac block 3
• Lidocaine has a lower profile of adverse hemodynamic effects but can cause central nervous system toxicity, especially in patients with compromised liver or renal function 4