What is the best treatment for a patient with monomorphic Ventricular Tachycardia (VTach)?

Treatment of Monomorphic Ventricular Tachycardia

The best treatment for monomorphic VT depends entirely on hemodynamic stability: immediate direct-current cardioversion for unstable patients, and intravenous procainamide for stable patients.

Step 1: Assess Hemodynamic Stability Immediately

First, determine if the patient is hemodynamically stable or unstable by looking for:

• Hypotension 1, 2
• Altered mental status 2
• Chest pain 2
• Acute heart failure 2
• Signs of shock 2

Any wide-QRS tachycardia should be presumed to be VT if the diagnosis is unclear 1.

Step 2A: If Hemodynamically UNSTABLE

Perform immediate direct-current cardioversion with appropriate sedation 1, 2. This is a Class I recommendation from the European Society of Cardiology 2.

• Provide sedation if the patient is conscious but hypotensive before cardioversion 2
• This can be done at any point in the treatment cascade 1

If VT Recurs After Cardioversion:

Administer intravenous amiodarone 1, 3:

• Loading dose: 150 mg over 10 minutes 1
• Followed by maintenance infusion 1
• FDA-approved for hemodynamically unstable VT refractory to other therapy 3
• For breakthrough VT/VF, give additional 150 mg supplemental infusions over 10 minutes 3

Step 2B: If Hemodynamically STABLE

Administer intravenous procainamide as first-line pharmacologic therapy 1, 2, 4. This has a Class IIa recommendation with Level B evidence from both the European Society of Cardiology and American Heart Association 1, 2.

Procainamide Dosing:

• 10 mg/kg at 50-100 mg/min intravenously over 10-20 minutes 1, 2, 4
• Monitor blood pressure and ECG continuously during administration 4
• Procainamide demonstrates the greatest efficacy among antiarrhythmic drugs 4

Contraindications to Procainamide:

• Severe heart failure 2
• Acute myocardial infarction 2

If Procainamide Fails or is Contraindicated:

Use intravenous amiodarone 1:

• Recommended for VT refractory to conversion with countershock or recurrent despite procainamide 1
• Has a Class IIb recommendation (weaker than procainamide) 4
• Initial dose: approximately 1000 mg over first 24 hours 3
• Maintenance infusion: 0.5 mg/min (720 mg per 24 hours) 3

Special Circumstances

VT Associated with Acute Myocardial Ischemia/Infarction:

Use intravenous lidocaine 1, 2:

• Initial bolus: 1 mg/kg 1, 2
• Additional boluses: 0.5 mg/kg every 8-10 minutes if needed 1, 2
• Consider urgent coronary angiography with revascularization 1

LV Fascicular VT (RBBB morphology with left axis deviation):

Use intravenous verapamil or beta-blockers 2 instead of standard VT medications.

Critical Pitfalls to Avoid

Never use calcium channel blockers (verapamil, diltiazem) for wide-QRS-complex tachycardia of unknown origin, especially with history of myocardial dysfunction 1. This is only appropriate for the specific subset of LV fascicular VT 2.

Amiodarone Administration Warnings:

• Must use volumetric infusion pump, not drop counter sets (which can underdose by 30%) 3
• Concentrations >2 mg/mL require central venous catheter 3
• Concentrations >3 mg/mL cause high incidence of peripheral vein phlebitis 3
• Loading infusions at much higher concentrations than recommended have resulted in hepatocellular necrosis, acute renal failure, and death 3

For Refractory Cases:

If standard cardioversion fails, consider double sequential synchronized cardioversion before adding medications that may worsen hypotension 5. Combination therapy with amiodarone, beta-blockers, and procainamide may be considered for repetitive monomorphic VT 1.