What is the treatment for a patient presenting with ventricular tachycardia (VT)?

Treatment for Ventricular Tachycardia

For hemodynamically unstable VT, perform immediate synchronized direct current cardioversion without delay; for stable monomorphic VT, procainamide is the first-line pharmacological agent, while amiodarone is preferred in patients with heart failure or suspected ischemia. 1, 2

Immediate Assessment of Hemodynamic Stability

The first critical decision point is determining whether the patient is hemodynamically stable or unstable. 2, 3

Unstable VT is defined by:

• Hypotension 2, 3
• Altered mental status or loss of consciousness 2, 4
• Signs of shock 4
• Chest pain or heart failure 3
• Heart rate ≥150 beats/min 3

Key principle: When the diagnosis between VT and supraventricular tachycardia with aberrancy is unclear, always presume and treat as VT. 1, 2, 4

Treatment Algorithm for Hemodynamically Unstable VT

Immediate synchronized DC cardioversion is the treatment of choice without any delay for pharmacological therapy. 1, 2

Cardioversion Protocol:

• If patient is conscious but unstable: Provide immediate sedation before cardioversion 1, 2, 3
• For monomorphic VT: Start with 100J synchronized discharge, escalating to 200J then 360J if needed 3, 4
• For polymorphic VT resembling VF: Use unsynchronized discharge of 200J 4
• For pulseless VT: Follow VF protocol with immediate defibrillation 3

Post-Cardioversion Management:

If VT recurs after successful cardioversion, initiate antiarrhythmic drug therapy to prevent acute reinitiation. 4 The preferred agents are intravenous amiodarone or procainamide. 4

Treatment Algorithm for Hemodynamically Stable Monomorphic VT

First-Line Pharmacological Treatment: Procainamide

Procainamide is the preferred first-line agent for stable monomorphic VT, demonstrating the greatest efficacy for rhythm conversion. 1, 2, 5

Dosing regimen:

• 10 mg/kg IV at 50-100 mg/min over 10-20 minutes 1, 2, 3
• Maximum dose: 10-20 mg/kg 3, 4
• Monitor closely: Blood pressure for hypotension and ECG for QRS widening during administration 3, 4

Important caveat: Procainamide is specifically recommended for patients without severe heart failure or acute MI. 2, 4

Alternative Agent: Amiodarone

Amiodarone is the preferred agent over procainamide in specific clinical contexts: 2, 4

• Patients with heart failure 2, 4
• Suspected myocardial ischemia 2, 4
• Impaired left ventricular function 4
• When VT is hemodynamically unstable, refractory to cardioversion, or recurrent despite other agents 1

Dosing regimen for amiodarone: 4, 6

• Loading dose: 150 mg IV over 10 minutes 4
• Followed by maintenance infusion: 1 mg/min for 6 hours, then 0.5 mg/min 6
• For breakthrough VT/VF: Additional 150 mg boluses over 10 minutes 6
• First 24-hour dose approximately 1000 mg 6

Critical limitation: Amiodarone's antiarrhythmic effect may take up to 30 minutes, making it less suitable for emergent situations requiring rapid conversion. 3 It is indicated for initiation of treatment in frequently recurring VF and hemodynamically unstable VT refractory to other therapy. 6

Other Pharmacological Options:

Sotalol: May be considered for hemodynamically stable sustained monomorphic VT, including post-MI patients. 1, 2

Lidocaine: Only moderately effective and less effective than procainamide, sotalol, or amiodarone; should be considered second-line. 2, 3, 4 It may be reasonable specifically for VT associated with acute myocardial ischemia or infarction. 1

Treatment of Polymorphic VT

With Normal QT Interval:

• First-line: Direct current cardioversion for hemodynamically compromised patients 1, 4
• For recurrent episodes: IV beta-blockers, especially if ischemia is suspected or cannot be excluded 1, 4
• Alternative: IV amiodarone loading for recurrent polymorphic VT in the absence of QT prolongation 1, 4
• Consider urgent revascularization when ischemia cannot be excluded 4

With Long QT (Torsades de Pointes):

• IV magnesium: 8 mmol bolus followed by 2.5 mmol/h infusion 3, 4
• Overdrive pacing: Atrial or ventricular 4
• Beta-blockers for congenital long QT syndrome 4
• Avoid isoproterenol in familial long QT syndrome 3

Long-Term Management and Special Considerations

Catheter Ablation Indications:

• Urgent catheter ablation is recommended for patients with scar-related heart disease presenting with incessant VT or electrical storm 2, 4
• Recommended for patients with ischemic heart disease and recurrent ICD shocks due to sustained VT 2, 4
• May be considered after a first episode of sustained VT in patients with ischemic heart disease and an ICD 2, 4
• May be considered for drug-refractory and poorly tolerated idiopathic VT 1

Oral Maintenance Therapy:

For idiopathic sustained VT, oral metoprolol, propranolol, or verapamil is recommended for long-term management. 1

VT Storm Management:

Beta-blockers with or without amiodarone are recommended for VT storm. 4 For recurrent or incessant VT, use IV amiodarone or procainamide followed by VT ablation. 4

Critical Pitfalls to Avoid

Never use calcium channel blockers (verapamil, diltiazem) for wide-complex tachycardia of unknown origin, especially in patients with structural heart disease or history of myocardial dysfunction, as they may precipitate hemodynamic collapse. 1, 3, 4 The only exception is when you are absolutely certain of fascicular VT diagnosis. 4

Do not delay cardioversion in unstable patients to attempt pharmacological conversion. 1, 2

Avoid assuming a wide-complex tachycardia is supraventricular - when in doubt, always treat as VT. 1, 4

Monitor for hypotension during procainamide administration and be prepared to stop infusion if significant hypotension or QRS widening >50% occurs. 3, 4

For IV amiodarone administration: Use concentrations ≤2 mg/mL for peripheral access to avoid phlebitis; higher concentrations require central venous access. 6 Administer through volumetric infusion pump, not drop counters, as surface properties may cause up to 30% underdosing. 6