What is the role of lignocaine (lidocaine) in the management of ventricular tachycardia?

Lignocaine (Lidocaine) in Ventricular Tachycardia

Lidocaine is a second-line antiarrhythmic agent for ventricular tachycardia, inferior in efficacy to procainamide, amiodarone, and sotalol, and should be reserved for refractory cases or when first-line agents are contraindicated or unavailable. 1

Evidence for Limited Efficacy

The evidence consistently demonstrates lidocaine's poor performance compared to alternative agents:

• Lidocaine was significantly less effective than procainamide in terminating hemodynamically stable monomorphic VT, with procainamide achieving termination in 12 of 15 patients versus only 3 of 14 with lidocaine (p <0.01). 2

• Lidocaine was less effective than sotalol (LOE 1), procainamide (LOE 2), and amiodarone (LOE 2) in multiple comparative studies. 1

• Retrospective analyses showed lidocaine was poorly effective when given to patients with or without myocardial infarction history with spontaneous sustained stable VT in the hospital setting. 1

• In a prospective evaluation of 128 patients with stable VT, only 10 (8%) had termination after lidocaine therapy, demonstrating its ineffectiveness in terminating stable VT not associated with acute myocardial infarction. 3

Current Guideline Recommendations

When to Consider Lidocaine

Lidocaine should be considered as a second-line agent for stable monomorphic VT when first-line therapies (procainamide, amiodarone) have failed or are contraindicated. 1, 4

• The European Society of Cardiology recommends intravenous lidocaine for recurrent sustained VT or VF not responding to beta-blockers or amiodarone, or when contraindications to amiodarone exist. 4

• Lidocaine may be particularly useful when VT is associated with acute myocardial ischemia or infarction, as it increases the ventricular fibrillatory threshold in ischemic tissue. 4, 5

When NOT to Use Lidocaine

• The American College of Cardiology does not recommend lidocaine as prophylactic treatment in patients with uncomplicated acute myocardial infarction, as trials failed to demonstrate mortality benefit and showed increased incidence of asystole. 1, 4

• Lidocaine should not be used for hemodynamically unstable VT—immediate synchronized DC cardioversion is indicated instead. 1, 6

Dosing Protocol

Initial Bolus Dosing

• Administer 1 mg/kg IV bolus (not exceeding 100 mg) over 2 minutes as the initial dose. 1, 4, 6

• Additional bolus injections of 0.5 mg/kg can be given every 8-10 minutes if necessary, to a maximum total of 4 mg/kg or 200 mg total. 1, 4, 6

Maintenance Infusion

• Start maintenance infusion at 20-50 μg/kg/min (1.4-3.5 mg/min in a 70 kg patient) or simplified as 2-4 mg/min. 1, 4, 6, 7

• Patients requiring more than one bolus dose may need higher maintenance doses up to 40-50 μg/kg/min. 1, 4

• Target therapeutic blood levels of up to 5 μg/ml. 1, 4

Critical Dosage Adjustments

Elderly Patients

• Reduce infusion rate in elderly patients due to increased risk of toxicity. 4

Heart Failure

• Reduce dosage significantly in heart failure patients, as the half-life increases to >4 hours (compared to 1-2 hours in normal subjects). 4

Cardiogenic Shock

• Significant reduction is needed in cardiogenic shock, as the half-life can exceed 20 hours. 4

Hepatic Dysfunction

• Reduce dosage in hepatic dysfunction, as lidocaine is primarily metabolized by the liver. 4

After 24-48 Hours

• Reduce infusion rate after 24-48 hours as the half-life of lidocaine increases over time. 6

Monitoring Requirements

• Monitor blood pressure and cardiovascular status closely, especially in patients with heart failure or hypotension. 4

• Consider measuring serum levels with prolonged or high infusion rates or if there are changes in neurologic condition. 4

• Watch for signs of toxicity including CNS symptoms: nausea, drowsiness, perioral numbness, dizziness, confusion, slurred speech, and more severe symptoms like muscle twitching, seizures, and respiratory depression. 6

• Lidocaine depresses myocardial contractility, requiring careful monitoring especially in hemodynamically compromised patients. 6

Treatment Algorithm for VT

Hemodynamically Unstable VT (Systolic BP ≤90 mmHg)

1. Immediate synchronized DC cardioversion (100J, 200J, 360J) with sedation if conscious. 1, 6
2. Do not delay cardioversion for drug administration. 1

Hemodynamically Stable Monomorphic VT

1. First-line: Procainamide (10 mg/kg at 100 mg/min) for patients without severe CHF or acute MI. 1
2. First-line: Amiodarone (150 mg over 10 minutes) for patients with or without severe CHF or acute MI. 1
3. Second-line: Lidocaine (1 mg/kg bolus, then maintenance infusion) if first-line agents fail or are contraindicated. 1, 4, 6

Refractory VT/VT Storm

1. Beta-blockers plus amiodarone as first-line therapy. 4, 7
2. Lidocaine as alternative or adjunct particularly when VT is related to myocardial ischemia. 7
3. Consider advanced strategies: overdrive pacing, general anesthesia, or spinal cord modulation for frequently recurring or incessant VT. 7

Common Pitfalls to Avoid

• Do not use lidocaine prophylactically in uncomplicated MI—it increases asystole risk without mortality benefit. 1, 4

• Do not persist with multiple antiarrhythmic drugs if the first agent fails—proceed to electrical cardioversion instead. 8

• Do not use standard doses in elderly, heart failure, or hepatic dysfunction patients—toxicity risk is substantially increased. 4, 6

• Do not confuse lidocaine's historical prominence with current evidence—it has been de-emphasized due to inefficacy and safety concerns. 9, 8