What is the treatment for scar-related ventricular tachycardia (VT)?

Treatment of Scar-Related Ventricular Tachycardia

Urgent catheter ablation is the recommended first-line treatment for patients with scar-related heart disease presenting with incessant VT or electrical storm, while ICD implantation with antiarrhythmic medication therapy is recommended for recurrent episodes of VT. 1

Initial Assessment and Management

• For hemodynamically unstable VT:

  • Immediate electrical cardioversion (synchronized at 100J for monomorphic VT, unsynchronized 200J for polymorphic VT) 2
  • Treat reversible causes (ischemia, electrolyte abnormalities, heart failure)

• For hemodynamically stable VT:

  • Pharmacological management while preparing for definitive treatment
  • Continuous cardiac monitoring and regular blood pressure assessment

Definitive Treatment Options

1. Catheter Ablation

Catheter ablation has evolved into a crucial treatment option for scar-related VT with strong evidence supporting its use:

• Primary indications 1, 2:

  • Incessant VT or electrical storm (Class I, Level B recommendation)
  • Recurrent ICD shocks due to sustained VT (Class I, Level B recommendation)
  • After first episode of sustained VT in patients with ischemic heart disease and an ICD (Class IIa, Level B)

• Ablation techniques 1, 3:

  • Scar dechanneling: Targets the exit site of the re-entry circuit
  • Linear lesion sets
  • Ablation of local abnormal ventricular activity (scar homogenization)
  • Substrate mapping during sinus rhythm for hemodynamically unstable VT

• Efficacy: Scar dechanneling alone can render 54.5% of patients non-inducible, with complete elimination of conducting channels being the strongest predictor of success 3

• Considerations:

  • Epicardial mapping and ablation are more often required in patients with dilated cardiomyopathy 1
  • Pre-procedural cardiac MRI can help identify the arrhythmogenic substrate 1, 4
  • Complications include damage to coronary vasculature, phrenic nerve palsy, or pericardial tamponade 1

2. Implantable Cardioverter Defibrillator (ICD)

• Indications:

  • Secondary prevention in survivors of VT/VF (31% reduction in mortality compared to amiodarone) 1
  • Primary prevention in high-risk patients with severely impaired left ventricular function 1

• Benefits:

  • Effectively terminates VT episodes but does not prevent recurrence 1
  • Improves survival in appropriately selected patients 1

• Limitations:

  • ICD shocks are associated with higher mortality and impaired quality of life 1
  • Psychological impact: anxiety (8-63%) and depression (5-41%) are common 1

3. Antiarrhythmic Medications

• Amiodarone 2, 5, 6:

  • Most effective pharmacological option for preventing VT recurrence
  • Loading: 300mg IV bolus, followed by 1mg/min for 6 hours, then 0.5mg/min
  • Maintenance: 200-400mg daily orally
  • Reduces ICD shocks when combined with beta-blockers
  • Side effects include neurologic toxicity (38% develop ataxia/tremor) 6

• Beta-blockers 2:

  • First-line for polymorphic VT storm
  • Metoprolol: 2.5-5.0mg IV every 2-5 minutes (maximum 15mg)

• Other options 2:

  • Procainamide: 20-30mg/min up to 12-17mg/kg, followed by 1-4mg/min
  • Lidocaine: useful for ischemia-related VT (1.0-1.5mg/kg bolus)
  • Sotalol: second-line option for stable sustained monomorphic VT

4. Surgical Ablation

• Indications 1, 7:

  • VT refractory to antiarrhythmic drug therapy after failure of catheter ablation (Class I, Level B)
  • Can be considered during cardiac surgery (bypass or valve) in patients with documented VT/VF (Class IIb, Level C)

• Approach: Surgical ablation guided by preoperative and intraoperative electrophysiological mapping 1

Treatment Algorithm

1. Assess hemodynamic stability:

   • If unstable → immediate electrical cardioversion
   • If stable → proceed with medical management while preparing for definitive treatment

2. Acute management:

   • Correct reversible causes (ischemia, electrolytes, drugs)
   • Initiate antiarrhythmic therapy (amiodarone preferred)

3. Definitive treatment:

   • For incessant VT/electrical storm → urgent catheter ablation
   • For recurrent episodes → ICD implantation + catheter ablation
   • For refractory cases after failed catheter ablation → consider surgical ablation

4. Long-term management:

   • Optimize heart failure therapy
   • Consider antiarrhythmic drugs to reduce ICD shocks
   • Regular monitoring for arrhythmia recurrence and device function

Special Considerations

• Concomitant amiodarone and ablation: Patients on amiodarone require less extensive ablation but may have higher VT recurrence rates if amiodarone is discontinued post-procedure 8

• Epicardial vs. endocardial approach: Some re-entry circuits involve both layers and may require comprehensive mapping of both surfaces for successful ablation 4

• Quality of life: Discussion of quality-of-life issues is recommended before ICD implantation and during disease progression (Class I, Level C) 1

• Psychological support: Assessment of psychological status and treatment of distress are recommended in patients with recurrent inappropriate shocks (Class I, Level C) 1