What is the comparison between procainamide and lidocaine for converting ventricular tachycardia (VT) with a pulse?

Procainamide vs Lidocaine for Converting VT with a Pulse

Procainamide is superior to lidocaine for converting hemodynamically stable ventricular tachycardia with a pulse, demonstrating significantly higher conversion rates (80% vs 21%) in head-to-head comparison. 1

Evidence-Based Comparison

Efficacy Data

Procainamide demonstrates markedly superior conversion rates compared to lidocaine:

• In the definitive randomized trial, procainamide (10 mg/kg) terminated VT in 12 of 15 patients (80%) versus lidocaine (1.5 mg/kg) which terminated only 3 of 14 patients (21%), p<0.01 1
• When analyzing total VT episodes, procainamide converted 20 of 26 episodes (77%) compared to lidocaine's 4 of 15 episodes (27%), p<0.01 1
• Procainamide successfully terminated 8 of 11 VTs that failed to respond to lidocaine, while lidocaine only terminated 1 of 1 VT that failed procainamide 1
• International consensus guidelines confirm lidocaine was less effective than procainamide (LOE 2) in terminating VT 2

Guideline Recommendations

Current guidelines clearly favor procainamide for stable monomorphic VT:

• Procainamide is recommended for patients with hemodynamically stable monomorphic VT who do not have severe congestive heart failure or acute myocardial infarction 2
• Lidocaine is considered second-line antiarrhythmic therapy for monomorphic VT, with conversion effectiveness of only approximately 20% 2, 3
• The 2010 International Consensus explicitly states procainamide demonstrated improved reversion rates over lidocaine in hemodynamically stable monomorphic VT 2

Clinical Algorithm for Drug Selection

Choose Procainamide When:

• Patient has hemodynamically stable monomorphic VT with pulse 2
• No severe congestive heart failure present 2
• No acute myocardial infarction in progress 2
• Normal renal function (procainamide requires dose adjustment in renal insufficiency) 2

Choose Lidocaine When:

• VT occurs in the setting of acute myocardial infarction 2
• Procainamide is contraindicated 2
• Patient has severe heart failure (procainamide has negative inotropic effects) 2
• Rapid administration needed (lidocaine bolus faster than procainamide infusion) 2

Immediate Cardioversion Instead When:

• Patient is hemodynamically unstable (hypotension, altered mental status, chest pain, heart failure) 4, 5
• Systolic blood pressure ≤90 mmHg 5

Dosing Regimens

Procainamide Dosing:

• Loading infusion: 10-15 mg/kg (500-1250 mg) at 20-50 mg/min 2
• Alternative: 10 mg/kg at 100 mg/min 1
• Maintenance infusion: 1-4 mg/min 2
• Stop infusion if: arrhythmia suppressed, hypotension develops, QRS widens >50%, or maximum dose reached 2

Lidocaine Dosing:

• Initial bolus: 1.0-1.5 mg/kg (75-100 mg) 2
• Additional boluses: 0.5-0.75 mg/kg every 5-10 minutes up to total 3 mg/kg 2
• Maintenance infusion: 1-4 mg/min (30-50 mcg/kg/min) 2

Critical Safety Considerations

Procainamide Warnings:

• May cause proarrhythmia including torsades de pointes 2
• Hypotension and negative inotropic effects require monitoring 2
• Reduce dose in renal insufficiency due to NAPA accumulation 2
• Significantly prolongs QRS width and QT interval 1
• Contraindicated in severe heart failure 2

Lidocaine Warnings:

• Volume of distribution and clearance reduced in heart failure 2
• Reduce infusion rate in elderly, heart failure, or hepatic dysfunction 4
• Generally well tolerated except in shock states 2
• Monitor for CNS toxicity (confusion, seizures) 5

Mechanism of Superior Efficacy

Procainamide's superior performance relates to its electrophysiologic effects:

• Procainamide significantly prolongs effective refractory period of ventricle, HV interval, and QRS duration 6
• Lidocaine does not significantly affect these parameters 6
• Procainamide's Class Ia sodium channel blockade with intermediate kinetics provides more sustained antiarrhythmic effect 2
• Procainamide's metabolite NAPA adds Class III antiarrhythmic activity 2

Common Pitfalls to Avoid

• Do not use lidocaine as first-line for stable VT outside the acute MI setting—procainamide is more effective 2, 1
• Do not give procainamide in severe heart failure or acute MI—use amiodarone instead 2
• Do not delay cardioversion if patient becomes hemodynamically unstable during drug infusion 4, 5
• Do not use verapamil or diltiazem for wide-complex tachycardia—may precipitate cardiovascular collapse 5
• Do not ignore renal function when dosing procainamide—NAPA accumulation increases torsades risk 2