What is the treatment for ventricular tachycardia (VT) using Amiodarone (Cordarone)?

Amiodarone (Cordarone) for Ventricular Tachycardia

Amiodarone is recommended for hemodynamically stable monomorphic VT with or without heart failure or acute MI, and for hemodynamically unstable VT that is refractory to electrical cardioversion or recurrent despite other therapies, but it is relatively ineffective (only 20-40% conversion rate) for acute termination of VT. 1

Clinical Decision Algorithm

Step 1: Assess Hemodynamic Stability

Hemodynamically unstable VT (hypotension, altered mental status, chest pain, pulmonary edema):

• Immediate synchronized electrical cardioversion is the treatment of choice 1
• If VT is refractory to cardioversion or recurs despite electrical therapy, then proceed to amiodarone 1

Hemodynamically stable monomorphic VT:

• Procainamide is the preferred first-line agent if the patient does NOT have severe heart failure or acute MI 1
• Amiodarone is the preferred first-line agent if the patient HAS severe heart failure or acute MI 1

Step 2: Amiodarone Dosing Protocol

For life-threatening ventricular arrhythmias (FDA-approved dosing): 2

• Initial loading dose: 150 mg IV over 10 minutes (in 100 mL D5W)
• Maintenance infusion: 1 mg/min for 6 hours
• Subsequent infusion: 0.5 mg/min for remaining 18 hours (total ~1000 mg over first 24 hours)
• For breakthrough VT/VF: Repeat the 150 mg bolus over 10 minutes 1, 2

Alternative dosing from guidelines: 1

• Some protocols use up to 300 mg IV bolus, but this increases hypotension risk

Step 3: Critical Monitoring Requirements

Mandatory continuous monitoring during IV administration: 1, 3

• ECG monitoring: Watch for bradycardia (occurs in 4.9% of patients), AV block, QT prolongation 3, 2
• Blood pressure: Hypotension occurs in 16% of patients; slow infusion rate if BP drops 1, 3, 2
• Heart rate: If HR decreases by ≥10 bpm, reduce infusion rate immediately 3

Absolute contraindications to IV amiodarone: 3, 2

• Second- or third-degree AV block without functioning pacemaker
• Marked sinus bradycardia
• Cardiogenic shock
• Known hypersensitivity to amiodarone or iodine

Step 4: Understanding Amiodarone's Limitations for Acute VT Termination

Amiodarone has poor acute termination rates for VT: 1, 4

• Only 20-40% conversion rate when used for acute termination of monomorphic VT 1
• One study showed only 29% (8 of 28 patients) successful termination within 20 minutes 4
• The class III effect (prolongation of repolarization) develops slowly, limiting acute efficacy 5, 4

Amiodarone's primary role is preventing recurrence, not acute termination: 1

• Two RCTs demonstrated that amiodarone reduces the number of life-threatening arrhythmias, required shocks, and episodes of symptomatic sustained VT in patients with recurrent refractory ventricular arrhythmias 1
• Most effective when used for 48-96 hours to stabilize patients 2

Step 5: Special Populations and Long-Term Considerations

Patients with ICDs and recurrent VT (electrical storm): 6

• First-line: ICD implantation for high-risk patients 6
• Second-line: Catheter ablation should be considered before long-term amiodarone 6
• Third-line: Beta-blockers combined with amiodarone reduce ICD shocks 6
• Fourth-line: Amiodarone monotherapy only if not candidates for ICD or ablation 6

Patients with heart failure and low ejection fraction: 6

• Amiodarone is hemodynamically well-tolerated in acute heart failure with ventricular arrhythmias 6
• However, the SCD-HeFT trial showed no survival benefit for empiric amiodarone in heart failure patients with LVEF ≤35% 6
• Overall neutral effects on survival in this population 6

Common Pitfalls and How to Avoid Them

Pitfall 1: Using amiodarone as first-line for stable monomorphic VT without heart failure

• Procainamide has superior efficacy (better reversion rates) in this setting 1
• Reserve amiodarone for patients with heart failure or acute MI 1

Pitfall 2: Expecting rapid VT termination with amiodarone

• Amiodarone's onset for class III effects is slow (2-24 hours for maximal effect) 5
• If immediate termination is needed, use electrical cardioversion 1
• Amiodarone works best for preventing recurrence after initial conversion 1

Pitfall 3: Administering amiodarone too rapidly

• Rapid bolus causes significant hypotension and bradycardia 1, 7
• Always infuse 150 mg over full 10 minutes, not faster 2
• Have vasopressors available if hypotension develops 2

Pitfall 4: Using amiodarone in patients with pre-existing bradycardia

• Drug-related bradycardia occurs in 4.9% of patients regardless of dose 3
• Relative contraindication if HR <60 bpm without pacemaker 3
• Only use if immediately life-threatening and no safer alternatives exist 3

Pitfall 5: Failing to adjust concomitant medications

• Reduce digoxin dose by 50% when starting amiodarone (digoxin levels double) 3
• Monitor INR weekly for first 6 weeks if on warfarin (amiodarone increases anticoagulation) 3
• Avoid grapefruit juice (inhibits metabolism and increases amiodarone levels) 3

Pitfall 6: Using calcium channel blockers for wide-complex tachycardia of unknown origin

• Verapamil and diltiazem should NOT be used for undifferentiated wide-complex tachycardia, especially with history of myocardial dysfunction 1
• Can cause hemodynamic collapse if the rhythm is actually VT 1

Administration Technique

Preferred route: 1

• Central venous catheter whenever possible
• Peripheral vein phlebitis occurs frequently with concentrations >2 mg/mL
• Use in-line filter during administration 1

If hypotension develops: 2

• Slow the infusion rate
• Add vasopressor drugs if needed
• Consider positive inotropic agents
• Provide volume expansion as appropriate