What is the role of Ventricular Tachycardia (Vt) in Structural Heart Disease?

From the Guidelines

Ventricular tachycardia (VT) in structural heart disease is a life-threatening arrhythmia that necessitates prompt evaluation and management, with implantable cardioverter-defibrillators (ICDs) being the cornerstone of treatment for patients with sustained VT and reduced ejection fraction (<35%). The role of VT in structural heart disease is complex and multifaceted, involving reentry circuits around myocardial scar tissue, creating a substrate for arrhythmia 1.

Key Considerations

• The mechanism of VT in structural heart disease typically involves reentry circuits around myocardial scar tissue, creating a substrate for arrhythmia 1.
• Antiarrhythmic medications, such as amiodarone, are typically used as adjunctive therapy, with a loading dose of 400-600mg daily for 1-2 weeks, then 200mg daily, despite its side effect profile 1.
• Beta-blockers, like metoprolol (25-200mg daily) or carvedilol (3.125-25mg twice daily), should be used in all patients if tolerated.
• For recurrent VT despite medical therapy, catheter ablation is recommended, particularly for scar-related VT in post-infarction patients 1.
• Acute management of hemodynamically unstable VT requires immediate electrical cardioversion at 100-200J, while stable VT may be treated with IV amiodarone (150mg over 10 minutes, followed by 1mg/min for 6 hours, then 0.5mg/min) 1.

Risk Stratification

• Risk stratification should include assessment of left ventricular function, heart failure status, and electrolyte abnormalities, with correction of any reversible causes such as ischemia or electrolyte disturbances 1.
• Patients with ventricular tachyarrhythmias following MI are at risk of catastrophic events such as cardiac arrest or sudden death, and that the risk is highest within the first 30–60 days following MI 1.
• Implantation of an ICD in this population is reasonable in selected patients in the absence of opportunities for revascularization 1.

Treatment Approach

• The treatment approach should prioritize ICD implantation for patients with sustained VT and reduced ejection fraction (<35%), particularly in those with prior myocardial infarction or non-ischemic cardiomyopathy.
• Catheter ablation may be effective in treating VT, particularly in patients with idiopathic VT or bundle branch reentry 1.
• Revascularization options should be implemented as an initial strategy before committing the patient to ICD therapy, especially when there is evidence of reversible ischemia responsible for the ventricular tachyarrhythmia 1.

From the FDA Drug Label

The DIAMOND trials were intended to determine whether TIKOSYN could reduce the risk of sudden death in patients with structural heart disease. The trials did not demonstrate a reduction in mortality; however, they provide reassurance that, when initiated carefully, in a hospital or equivalent setting, TIKOSYN did not increase mortality in patients with structural heart disease, an important finding because other antiarrhythmics [notably the Class IC antiarrhythmics studied in the Cardiac Arrhythmia Suppression Trial (CAST) and a pure Class III antiarrhythmic, d-sotalol (SWORD)] have increased mortality in post-infarction populations. Torsade de Pointes occurred in 25/762 patients (3.3%) receiving TIKOSYN in the DIAMOND CHF study and in 7/749 patients (0.9%) in the DIAMOND MI study.

The role of Ventricular Tachycardia (Vt) in Structural Heart Disease is not directly supported by the provided drug labels. However, the labels do discuss the risk of Torsade de Pointes, a type of ventricular tachycardia, in patients with structural heart disease taking dofetilide. The DIAMOND trials provide evidence that dofetilide does not increase mortality in patients with structural heart disease, but they do not specifically address the role of ventricular tachycardia in these patients 2.

From the Research

Role of Ventricular Tachycardia in Structural Heart Disease

• Ventricular Tachycardia (VT) in patients with structural heart disease carries an elevated risk for sudden cardiac death (SCD) 3.
• Implantable cardioverter-defibrillators (ICDs) are the mainstay of therapy for VT in structural heart disease, but catheter ablation may be used as adjunctive therapy to treat or prevent repetitive ICD therapies 3, 4.
• The goal of catheter ablation is to reduce VT recurrence and ICD shocks, and in some cases, improve left ventricular function and decrease the risk of SCD 3, 5.

Management of Ventricular Tachycardia

• The management of VT in patients with structural heart disease is multifaceted and often requires a combination of therapeutic techniques 4.
• Antiarrhythmic drugs can help reduce episodes of VT, but have not been shown to decrease mortality in this patient population 4.
• Catheter ablation is an effective treatment option for patients with VT in the setting of structural heart disease, and can reduce the number of ICD shocks 5, 6.

Long-term Outcomes and Recommendations

• The long-term outcomes of VT ablation in patients with different types of structural heart disease are variable, and the approach to mapping and ablation depends on the underlying heart disease etiology, VT inducibility, and hemodynamic stability 5, 6.
• The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society position statement provides recommendations for the management of VT and fibrillation in patients with structural heart disease, including initial evaluation, acute therapy, and chronic suppressive therapy 7.