What is the treatment for wide complex tachycardia (WCT)?

Treatment of Wide Complex Tachycardia

For wide complex tachycardia (WCT), treatment should be based on hemodynamic stability, with immediate synchronized cardioversion for unstable patients and appropriate pharmacological therapy for stable patients based on the specific type of WCT.

Initial Assessment and Management

Unstable Patient

• Immediate synchronized cardioversion is the first-line treatment for hemodynamically unstable patients with WCT (Class I, LOE B) 1, 2
• If defibrillator is not immediately available, consider precordial thump (Class IIb, LOE C) 1, 2
• Signs of instability include:
  • Hypotension
  • Altered mental status
  • Signs of shock
  • Acute heart failure
  • Chest pain

Stable Patient

1. Obtain 12-lead ECG to help determine the etiology of the WCT
2. Assess regularity of rhythm:
   • Regular WCT: Likely ventricular tachycardia (VT) or supraventricular tachycardia (SVT) with aberrancy
   • Irregular WCT: Consider atrial fibrillation with aberrancy, pre-excited atrial fibrillation, or polymorphic VT/torsades de pointes

Pharmacological Management for Stable WCT

Regular Monomorphic WCT

• First-line: IV procainamide (1.5 mg/kg over 5 minutes) (Class IIa, LOE B) 1, 2

  • Avoid in patients with prolonged QT interval or severe heart failure

• Alternative: IV amiodarone (150 mg over 10 minutes) (Class IIa, LOE B) 1, 2, 3

  • Preferred in patients with impaired left ventricular function or heart failure
  • Maximum dose: 2.2 g IV per 24 hours

• For diagnostic purposes: IV adenosine may be considered for regular monomorphic WCT of uncertain origin (Class IIb, LOE B) 1, 2

  • Use with caution as it may precipitate ventricular fibrillation in patients with coronary artery disease
  • Contraindicated in irregular or polymorphic WCT

• Additional option: Sotalol 1.5 mg/kg IV over 5 minutes (Class IIb, LOE B) 1

  • Avoid in patients with prolonged QT interval

Polymorphic WCT

• With long QT syndrome:

  • IV magnesium
  • Cardiac pacing
  • β-blockers (avoid isoproterenol) 1, 2

• Without long QT syndrome:

  • IV β-blockers for ischemic VT or catecholaminergic VT
  • Consider isoproterenol in other cases 1, 2

• For torsades de pointes:

  • Withdraw offending drugs
  • Correct electrolyte abnormalities (Class I, LOE A) 2

Important Contraindications and Precautions

• Never use calcium channel blockers (verapamil, diltiazem) for WCT of unknown origin due to risk of catastrophic hemodynamic collapse if the rhythm is VT (Class III, LOE C) 2

• Avoid concomitant use of IV calcium-channel blockers and beta blockers due to potential hypotensive and bradycardic effects 2

• Do not administer multiple antiarrhythmic agents without expert consultation (Class III, LOE B) 1

Post-Conversion Management

• After successful termination of VT, patients should be referred to an arrhythmia specialist for further evaluation 2

• Consider long-term management options including catheter ablation or chronic drug therapy 2

• Continuously monitor for deterioration in hemodynamic status and be prepared to immediately perform synchronized cardioversion if the patient becomes unstable 2

Diagnostic Considerations

When the diagnosis is uncertain, consider these features suggestive of VT:

• RS interval >100 ms in any precordial lead
• Negative concordance in precordial leads
• Presence of ventricular fusion beats
• QR complexes (present in ~40% of post-MI VT)
• History of previous myocardial infarction 2

Remember that most wide complex tachycardias are ventricular in origin, and when in doubt, it is safer to treat as VT rather than SVT with aberrancy 4.