What medications are used to treat ventricular tachycardia?

Medications for Ventricular Tachycardia

For hemodynamically stable VT, amiodarone 150 mg IV over 10 minutes followed by 1.0 mg/min infusion for 6 hours (then 0.5 mg/min) is the first-line pharmacological treatment, particularly in patients with structural heart disease or heart failure. 1, 2, 3

Critical First Step: Assess Hemodynamic Stability

Before selecting any medication, determine if the patient has a pulse and assess for adverse signs 4, 1, 2:

• Hypotension (systolic BP ≤ 90 mm Hg)
• Chest pain or acute heart failure
• Altered mental status or signs of shock
• Heart rate ≥ 150 beats/min

If pulseless or hemodynamically unstable, proceed immediately to synchronized cardioversion (100J, 200J, 360J) rather than relying on medications 4, 5, 2. Pharmacological treatment is secondary to electrical therapy in these cases 4.

First-Line Medications for Stable VT

Amiodarone (Preferred Agent)

Amiodarone is the preferred antiarrhythmic for hemodynamically stable VT, especially in patients with structural heart disease, heart failure, or when VT is refractory to other agents 1, 2, 3.

Dosing regimen 1, 2, 3:

• Loading dose: 150 mg IV over 10 minutes
• Maintenance infusion: 1.0 mg/min for 6 hours
• Then: 0.5 mg/min thereafter
• For cardiac arrest or life-threatening situations, can give over 15 minutes and repeat after one hour 4
• Additional loading of up to 900 mg over 24 hours may be given 4

Important considerations:

• Antiarrhythmic effect may take up to 30 minutes 4
• Combine with IV beta-blockers for optimal efficacy, particularly in VT storm 1, 5, 2
• Monitor closely for hypotension (most common adverse effect), bradycardia, and AV block 1, 6, 7
• Can be used safely in patients with heart failure, bundle branch block, or acute MI 8

Procainamide (Alternative with Highest Efficacy)

Procainamide demonstrates the greatest efficacy among medical options for stable monomorphic VT but is reserved for patients without severe heart failure or acute infarction 4, 5, 2, 9.

Dosing regimen 5, 2, 9:

• Loading infusion: 20-30 mg/min up to maximum 10-17 mg/kg
• Maintenance infusion: 1-4 mg/min
• Reduce infusion rates in patients with renal dysfunction 5, 2

Lidocaine (Second-Line, Ischemia-Related VT)

Lidocaine is relegated to second-line status and is particularly useful when VT is thought to be ischemia-related 1, 5, 2.

Dosing regimen 4, 1, 2:

• Initial bolus: 1.0-1.5 mg/kg IV (or 100 mg for cardiac arrest)
• Supplemental boluses: 0.5-0.75 mg/kg every 5-10 minutes to maximum 3 mg/kg total
• Maintenance infusion: 2-4 mg/min
• Can repeat 100 mg bolus after 5-10 minutes if needed 4

Important considerations:

• Reduce infusion rates in older patients and those with heart failure or hepatic dysfunction 5
• Less effective than sotalol, procainamide, and amiodarone 4
• Has no effect on supraventricular tachycardia 4
• Toxic levels can produce paresthesia, drowsiness, muscular twitching, or seizures 4

Special Situations

Torsades de Pointes (Polymorphic VT with Long QT)

Magnesium is the treatment of choice 4, 1, 5, 2:

• Dose: 8 mmol (2 grams) IV bolus immediately
• Maintenance: 2.5 mmol/hour infusion
• Particularly effective if hypomagnesemia is suspected or in setting of acute MI 4, 1

VT Storm (Recurrent/Incessant VT)

IV beta-blockers combined with amiodarone is first-line therapy 1, 5, 2:

• Beta-blockers are the single most effective therapy for polymorphic VT storm 1, 5
• Use same amiodarone dosing as above 5
• Consider catheter ablation for refractory cases 5

Refractory VT (Not Responding to Standard Agents)

Bretylium can be used for refractory VT 4:

• Dose: 5 mg/kg diluted with 100 mL dextrose
• If unsuccessful, give 10 mg/kg 4
• Antiarrhythmic effect may take up to 20 minutes 4
• Warning: Initially causes transient hypertension, then pronounced hypotension 4

Critical Medications to AVOID in VT

Never use the following in wide-complex tachycardia or VT 2:

• Calcium channel blockers (verapamil, diltiazem): Can precipitate VT/VF or profound hypotension 2
• Adenosine: Contraindicated in wide-complex tachycardia 2
• Class IC antiarrhythmics (flecainide, propafenone): Especially in patients with prior MI or structural heart disease 5

Practical Administration Pearls

Always follow these protocols 4, 1, 2:

• Administer all IV drugs through peripheral vein followed by 20 mL saline bolus to aid delivery to central circulation 4, 1
• Correct electrolytes (potassium, magnesium) before and during antiarrhythmic therapy 1, 2
• Keep cardioversion equipment immediately available when administering any antiarrhythmic 2
• Monitor continuously for hypotension, bradycardia, and AV block during administration 1, 2

Common Pitfalls to Avoid

• Do not delay cardioversion in unstable patients while attempting pharmacological therapy 4, 5
• Do not use amiodarone as first-line unless patient is clinically stable, as antiarrhythmic effect takes up to 30 minutes 4
• Do not use procainamide in patients with severe heart failure or acute MI 4, 5
• Do not combine AV nodal blocking agents with longer duration of action (e.g., calcium channel blockers with beta-blockers) as profound bradycardia can develop 4
• Do not use prophylactic antiarrhythmics other than beta-blockers, as they may be harmful 5