What are the causes and treatment options for recurrent ventricular tachycardia (VT)?

Causes and Management of Recurrent Ventricular Tachycardia

Primary Causes of Recurrent VT

The most common cause of recurrent monomorphic VT is myocardial scar from prior infarction in patients with structural heart disease, while acute coronary ischemia is the primary trigger for ventricular fibrillation. 1

Structural Heart Disease Etiologies

• Coronary artery disease with prior MI represents the predominant substrate, accounting for 73-83% of patients with recurrent VT, typically with reduced LVEF (32-45%) 2
• Nonischemic dilated cardiomyopathy carries high risk for recurrent cardiac arrest after initial VT/VF episode 2
• Hypertrophic cardiomyopathy is the most common cause of cardiac arrest in individuals younger than 40 years, often triggered by exertion 2
• Other cardiomyopathies including arrhythmogenic right ventricular cardiomyopathy, sarcoidosis, Chagas disease, and repaired congenital heart disease 3

Acute Triggers and Reversible Causes

• Ongoing myocardial ischemia or incomplete revascularization - recurrent polymorphic VT or VF may indicate incomplete reperfusion or recurrent acute ischemia 2
• Electrolyte imbalances require immediate correction 2
• PVCs arising from partially injured Purkinje fibers can trigger recurrent VF episodes, particularly in the setting of acute coronary syndromes 2

Treatment Algorithm for Recurrent VT

Immediate Management

For hemodynamically unstable recurrent VT, immediate direct-current cardioversion with appropriate sedation is mandatory at any point in the treatment cascade. 4

• Beta-blockers should be administered early (possibly IV) to prevent recurrent arrhythmias 2
• Deep sedation may help reduce episodes of VT or VF 2
• Amiodarone (150-300 mg IV bolus) should be considered only if episodes are frequent and cannot be controlled by successive cardioversion 2
• Intravenous lidocaine may be considered for recurrent sustained VT or VF not responding to beta-blockers or amiodarone 2

Addressing Underlying Substrate

Prompt and complete coronary revascularization is the primary therapy when ischemia directly implicates the VT, and this must be evaluated urgently with coronary angiography. 2

• Immediate coronary angiography should be considered in recurrent polymorphic VT degenerating into VF 2
• If coronary revascularization is not possible and significant LV dysfunction exists, ICD becomes primary therapy 2
• Correction of electrolyte imbalances is mandatory 2

Catheter Ablation Strategy

Radiofrequency catheter ablation at a specialized center followed by ICD implantation should be considered for recurrent VT, VF, or electrical storms despite optimal medical treatment. 2

• Early referral to specialized ablation centers is critical for patients with VT/VF storms 2
• Catheter ablation has been proven in two prospective randomized trials to decrease subsequent ICD shocks and prevent recurrent VT episodes in ischemic heart disease 2
• For VF triggered by PVCs from injured Purkinje fibers, catheter ablation is very effective and should be considered 2
• Epicardial mapping and ablation are more frequently required in dilated cardiomyopathy or ARVC 2

Device Therapy

ICD is the preferred treatment for secondary prevention in patients resuscitated from VT/VF, as it has demonstrated superior survival benefit compared to antiarrhythmic drugs alone. 2

• ICD is superior to amiodarone for secondary prevention, with benefit demonstrated in both ischemic and nonischemic cardiomyopathy 2
• Patients with reduced LV function experience greater benefit with ICD therapy 2
• Implantation of LV assist device or extracorporeal life support should be considered in hemodynamically unstable patients with recurrent VT/VF despite optimal therapy 2

Antiarrhythmic Drug Therapy

Beta-blockers in combination with amiodarone reduce the number of ICD shocks, though side effects may result in discontinuation. 2

• Prophylactic antiarrhythmic drugs (other than beta-blockers) are not recommended as they have not proven beneficial and may be harmful 2
• Amiodarone remains the safest antiarrhythmic when drug therapy is necessary, with neutral effects on survival in reduced ejection fraction 5
• Transvenous catheter overdrive stimulation should be considered if VT is frequently recurrent despite antiarrhythmic drugs and catheter ablation is not possible 2

Surgical Ablation

Surgical ablation guided by electrophysiological mapping is recommended in patients with VT refractory to antiarrhythmic drugs after failure of catheter ablation by experienced electrophysiologists. 2

Critical Pitfalls to Avoid

• Never use calcium channel blockers (verapamil, diltiazem) to terminate wide-QRS-complex tachycardia of unknown origin, especially with myocardial dysfunction 4, 5
• Do not assume new MI caused the VT when sustained VT/VF is accompanied by modest cardiac enzyme elevations - prolonged VT episodes can elevate troponin due to supply-demand mismatch 2
• Avoid class IC antiarrhythmic drugs (flecainide, propafenone) in structural heart disease or prior MI due to increased mortality risk 5
• Do not delay revascularization - incomplete reperfusion is a common reversible cause that must be addressed urgently 2