What is the initial management of ventricular tachycardia, including treatment for hemodynamically stable and unstable patients?

Initial Management of Ventricular Tachycardia

For hemodynamically unstable VT, perform immediate synchronized cardioversion without delay; for hemodynamically stable monomorphic VT, procainamide is the first-line pharmacologic agent, while amiodarone is preferred when severe heart failure or acute MI is present. 1

Hemodynamically Unstable VT

Immediate electrical cardioversion is mandatory for any patient with VT causing hypotension, altered mental status, shock, chest pain, or acute heart failure. 1

• Presume any unstable wide-complex tachycardia is VT and proceed directly to cardioversion 1
• Administer sedation to conscious patients immediately before cardioversion, but do not delay the procedure 1, 2
• Use synchronized cardioversion at maximum output initially 1
• A precordial thump may be considered only for witnessed, monitored unstable VT if a defibrillator is not immediately available (Class IIb) 1
• If the rhythm deteriorates to ventricular fibrillation or polymorphic VT, switch to unsynchronized defibrillation 1

Hemodynamically Stable Monomorphic VT

Initial Assessment and Monitoring

• Obtain a 12-lead ECG immediately to evaluate rhythm characteristics and guide therapy 1, 2
• Ensure continuous cardiac monitoring, oxygen administration, and secure IV/IO access 1, 2
• Consider expert consultation for all stable wide-complex tachycardias 1

Pharmacologic Management Algorithm

For stable monomorphic VT without severe heart failure or acute MI:

• Procainamide is the first-line agent with maximum dose of 10 mg/kg at 50-100 mg/min IV over 10-20 minutes 1, 3
• Monitor blood pressure and ECG continuously during infusion 3
• Procainamide demonstrates the greatest efficacy among antiarrhythmic options (Class IIa recommendation) 1, 3

For stable monomorphic VT with severe heart failure or acute MI:

• Amiodarone is the preferred agent: 150 mg IV over 10 minutes, may repeat dosing 1, 2
• Amiodarone is recommended for all patients with stable monomorphic VT when heart failure or ischemia is present or suspected 1, 2

Alternative agents (less preferred):

• Sotalol 1.5 mg/kg IV over 5 minutes may be considered for stable sustained monomorphic VT, including patients with acute MI 1
• Avoid sotalol in patients with prolonged QT interval 1
• Lidocaine is only moderately effective and should not be first-line 1

Special Consideration: Undifferentiated Regular Wide-Complex Tachycardia

• If unable to definitively distinguish VT from SVT with aberrancy, treat as VT 1
• IV adenosine may be considered for diagnostic and therapeutic purposes if the rhythm is regular and QRS is monomorphic (Class IIb) 1
• Critical pitfall: Never give adenosine for unstable, irregular, or polymorphic wide-complex tachycardia 1

Polymorphic VT Management

Polymorphic VT requires immediate assessment for QT interval and underlying cause:

• With prolonged QT (acquired): IV magnesium is first-line; consider pacing or IV isoproterenol if bradycardia or pause-dependent 1
• With prolonged QT (familial long QT syndrome): IV magnesium, pacing, and beta-blockers; avoid isoproterenol 1
• Without long QT syndrome: May respond to IV beta-blockers (ischemic or catecholaminergic VT) or isoproterenol 1
• Proceed to immediate cardioversion if hemodynamically unstable 1

Critical Pitfalls to Avoid

• Never use verapamil, diltiazem, or other AV nodal blocking agents for wide-complex tachycardia of uncertain etiology—these can cause hemodynamic collapse in VT 1, 2
• Do not use adenosine in unclear diagnoses with coronary disease risk—may precipitate ventricular fibrillation or accelerate ventricular rates in pre-excited atrial fibrillation 1, 2
• Do not delay cardioversion in unstable patients to attempt pharmacologic conversion 1, 2
• Avoid combining antiarrhythmic agents (particularly amiodarone and procainamide) due to additive toxicity 1
• Correct electrolyte abnormalities (potassium, magnesium, calcium) before or during antiarrhythmic therapy to reduce proarrhythmic risk 2

Post-Conversion Management

• Maintain continuous monitoring for recurrence 1, 2
• If VT recurs despite initial successful termination, consider IV amiodarone to prevent further episodes 1, 2
• Urgent catheter ablation is recommended for patients with scar-related heart disease presenting with incessant VT or electrical storm 1
• Evaluate and treat reversible causes including acute ischemia, electrolyte disturbances, and drug toxicity 2, 4