What is the preferred medication between amiodarone and procainamide (Procanbid (procainamide)) for treating ventricular tachycardia (VT)?

Procainamide vs Amiodarone for Ventricular Tachycardia

Procainamide is the preferred first-line medication for hemodynamically stable monomorphic ventricular tachycardia (VT) in patients without severe congestive heart failure or acute myocardial infarction, while amiodarone is recommended for patients with VT who have severe heart failure or acute myocardial infarction. 1

Treatment Algorithm for VT

Step 1: Assess Hemodynamic Stability

• Unstable VT (hypotension, altered mental status, chest pain, heart failure)

  • Immediate synchronized electrical cardioversion is the first-line treatment 1
  • After cardioversion, IV amiodarone should be initiated to prevent recurrence

• Stable VT

  • Proceed to medication therapy based on cardiac function and comorbidities

Step 2: Choose Medication Based on Cardiac Function

For Stable Monomorphic VT:

• Without severe heart failure or acute MI:

  • First choice: IV Procainamide (10 mg/kg over 20 min) 1
  • Higher efficacy rate (67% vs 38% for amiodarone) 2
  • Fewer major cardiac adverse events (9% vs 41% for amiodarone) 2

• With severe heart failure or acute MI:

  • First choice: IV Amiodarone (150 mg over 10 min, followed by infusion) 1, 3
  • Safer in patients with poor left ventricular function 4
  • FDA approved for hemodynamically unstable VT 3

For Polymorphic VT:

• With long QT syndrome:
  • IV magnesium, pacing, and beta-blockers 1
• Without long QT syndrome:
  • IV beta-blockers (if ischemia suspected)
  • IV amiodarone loading 1

Dosing and Administration

Procainamide

• Dose: 10 mg/kg IV over 20 minutes 1
• Monitor for hypotension and QT prolongation
• Contraindicated in severe heart failure and acute MI

Amiodarone

• Loading dose: 150 mg IV over 10 minutes
• Followed by: 1 mg/min for 6 hours
• Then: 0.5 mg/min thereafter 3
• For breakthrough VT episodes, repeat loading dose 3

Evidence Strength and Considerations

The 2017 PROCAMIO study provides the strongest recent evidence, showing procainamide to be superior to amiodarone for stable VT with:

• Higher termination rates (67% vs 38%)
• Fewer adverse events (9% vs 41%)
• Better outcomes even in patients with structural heart disease 2

However, amiodarone remains the drug of choice for patients with:

• Severely reduced left ventricular function (LVEF ≤20%) 4
• Acute myocardial infarction 1
• Hemodynamically unstable VT 3

Important Caveats and Pitfalls

1. Do not use calcium channel blockers (verapamil, diltiazem) for wide-complex tachycardias of unknown origin, especially in patients with myocardial dysfunction 1

2. Continuous cardiac monitoring is essential during administration of both medications

3. Hypotension risk:

   • Procainamide: 19% of patients may experience significant hypotension 5
   • Amiodarone: 6% of patients may experience significant hypotension 5

4. QT prolongation: Both drugs can prolong QT interval; avoid using them in combination 1

5. Always have defibrillator immediately available during administration of either medication 1

6. Correct electrolyte abnormalities (particularly potassium and magnesium) to prevent recurrence of VT 4

In summary, while both medications are effective for treating VT, procainamide shows superior efficacy and safety for hemodynamically stable monomorphic VT in patients without severe heart failure or acute MI, while amiodarone remains the preferred choice for patients with these conditions.