What is the appropriate treatment for ventricular tachycardia?

Treatment for Ventricular Tachycardia

For hemodynamically unstable VT (systolic BP <90 mmHg, altered mental status, shock, acute heart failure, or chest pain), perform immediate synchronized DC cardioversion starting at 100J for monomorphic VT or 200J unsynchronized for polymorphic VT, escalating as needed—this is the definitive first-line treatment. 1, 2

Initial Assessment: Determining Stability

Hemodynamic instability is defined by any of the following 1, 2:

• Systolic blood pressure <90 mmHg
• Altered mental status or loss of consciousness
• Clinical signs of shock (cold extremities, poor perfusion)
• Acute heart failure (pulmonary edema, severe dyspnea)
• Ongoing chest pain suggesting ischemia
• Heart rate ≥150 bpm with symptoms

If any of these are present, proceed directly to electrical cardioversion without delay. 1, 2

Hemodynamically Unstable VT: Electrical Cardioversion Protocol

Synchronized cardioversion is the only appropriate initial treatment for unstable VT. 3, 1, 2

Energy Settings:

• Monomorphic VT with rate >150 bpm: Start with 100J synchronized shock 1, 2
• Polymorphic VT resembling VF: Use 200J unsynchronized defibrillation 1, 2
• If initial shock fails: Escalate to 200J, then 360J 1

Key Points:

• Sedate the conscious but unstable patient immediately before cardioversion 3, 1
• A precordial thump may be attempted in witnessed, monitored VT while equipment is prepared 2
• Never delay cardioversion for pharmacologic therapy in unstable patients 2

Hemodynamically Stable Monomorphic VT: Treatment Algorithm

Even in stable patients, synchronized electrical cardioversion remains the most effective first-line therapy and may be used immediately. 2, 4 However, pharmacologic options are reasonable when cardioversion is not preferred or available.

Pharmacologic Management Based on Cardiac Function:

Patients WITHOUT heart failure, acute MI, or LVEF >40%:

Procainamide is the preferred first-line agent, demonstrating the greatest efficacy for rhythm conversion. 3, 1, 2, 4

• Dosing: 10 mg/kg IV at 50-100 mg/min over 10-20 minutes (maximum 10-20 mg/kg) 3, 1
• Monitoring: Closely monitor blood pressure and ECG during infusion 2
• Alternative: IV flecainide may be considered 2

Patients WITH heart failure, suspected ischemia, or LVEF ≤40%:

Amiodarone is preferred over procainamide due to better tolerability in these settings. 3, 1, 2

• Dosing: 150 mg (5 mg/kg) IV over 10 minutes, then 1 mg/min infusion for 6 hours, then 0.5 mg/min 1, 5
• Important limitation: Amiodarone's class III effect has a slow onset (20-30 minutes) and is not ideal for early conversion 2
• FDA indication: Approved for frequently recurring VF and hemodynamically unstable VT refractory to other therapy 5

Second-Line Agents:

• Sotalol: May be considered for stable sustained monomorphic VT, including post-MI patients 6, 3, 2
• Lidocaine: Only moderately effective and less effective than procainamide, sotalol, or amiodarone—reserve as second-line 6, 3, 2

Special Case: Left Ventricular Fascicular VT

For fascicular VT (RBBB morphology with left axis deviation), use IV verapamil or beta-blockers as first-line agents. 2 This is the only scenario where calcium channel blockers are safe in VT. 2

Polymorphic VT: Specific Management

Polymorphic VT with Normal QT (Likely Ischemia-Related):

• Treat underlying ischemia aggressively 1
• Consider IV beta-blockers 1
• Urgent revascularization when ischemia cannot be excluded 2

Polymorphic VT with Prolonged QT (Torsades de Pointes):

• IV magnesium sulfate: 8 mmol bolus followed by 2.5 mmol/h infusion 1
• Overdrive pacing (atrial or ventricular) 2
• Beta-blockers for congenital long QT syndrome 6, 2
• Avoid isoproterenol in familial long QT 6

Polymorphic VT with Bradycardia or Pause-Dependent:

• Consider pacing or IV isoproterenol 6

Critical Contraindications and Pitfalls

NEVER Use Calcium Channel Blockers (Verapamil, Diltiazem) for VT with Structural Heart Disease:

These agents can precipitate ventricular fibrillation and hemodynamic collapse. 3, 2 The only exception is confirmed fascicular VT. 2

When in Doubt, Treat as VT:

Always assume wide-complex tachycardia is VT unless proven otherwise—never assume it is supraventricular. 2 The risk of undertreating VT far exceeds the risk of treating SVT as VT. 2

Avoid AV Nodal Blocking Agents:

Do not use adenosine, digoxin, or other AV nodal blockers for wide-complex tachycardia unless supraventricular origin is certain. 2

After Amiodarone Loading:

If VT persists after full amiodarone loading, proceed immediately to synchronized cardioversion rather than waiting for drug effect. 2 The therapeutic effect requires 20-30 minutes and further delay increases risk of hemodynamic collapse. 2

Long-Term Management and Catheter Ablation

Urgent Catheter Ablation Indications (Class I):

• Scar-related heart disease with incessant VT or electrical storm 3, 1, 2
• Ischemic heart disease with recurrent ICD shocks due to sustained VT 3, 1, 2

Consider Catheter Ablation (Class IIa):

• After first episode of sustained VT in patients with ischemic heart disease and an ICD 3, 1, 2

ICD Implantation (Class I):

• Survivors of cardiac arrest with documented VT/VF not due to reversible cause 2
• Sustained VT with severe hemodynamic compromise (syncope, near-syncope, heart failure, shock, angina) 2

Do NOT Implant ICD (Class III):

• VT/VF occurring within 48 hours of acute MI (transient/reversible cause) 2
• Incessant VT where ablation is preferred first 2
• Terminal illness with life expectancy <6 months 2

Recurrent or Refractory VT

For recurrent VT after cardioversion, use IV antiarrhythmic drugs (procainamide or amiodarone) to prevent acute reinitiation, followed by consideration of VT ablation. 6, 2

For VT storm, use beta-blockers with or without amiodarone, and proceed to urgent catheter ablation. 2