Fascicular Ventricular Tachycardia (Fascicular VT)

Introduction

Fascicular ventricular tachycardia (Fascicular VT) is a specific type of idiopathic VT, meaning it occurs in the absence of structural heart disease. It is typically seen in young adults and has a relatively benign prognosis compared to other forms of VT. This arrhythmia originates in the fascicles of the left bundle branch of the heart’s conduction system.

Key Characteristics

• Common in young patients (often males, 15-40 years old) without structural heart disease.
• Originates from the left fascicles, usually the posterior fascicle.
• Responds well to verapamil, making it different from other ventricular arrhythmias.
• Typically presents with a right bundle branch block (RBBB) pattern and left axis deviation on ECG.

Clinical Presentation

Patients with fascicular VT may experience: - Palpitations (rapid heartbeat sensation) - Dizziness - Syncope (fainting) in rare cases - Symptoms often triggered by exercise or stress

Diagnosis

The diagnosis is made using: - Electrocardiogram (ECG): - RBBB pattern with left axis deviation (posterior fascicular VT) - Narrower QRS complexes (compared to other types of VT) - Electrophysiology Study: Helps confirm the diagnosis and guide catheter ablation. - Echocardiography and MRI: To rule out structural heart disease.

Treatment

Acute Treatment

• Intravenous Verapamil (first-line treatment as this VT is dependent on calcium channels).
• Beta-blockers in some cases.
• Cardioversion if the patient is hemodynamically unstable.

Long-term Management

• Catheter Ablation: This is often curative and is preferred for symptomatic or recurrent cases.
• Medications: Verapamil or beta-blockers can be used for less frequent episodes.
• Lifestyle Modification: Avoiding triggers such as exercise or stress in susceptible individuals.

Prognosis

Fascicular VT is generally not life-threatening, and most patients have an excellent prognosis, especially after successful catheter ablation.

Conclusion

Fascicular VT is an important differential diagnosis in young patients presenting with VT. It has a unique presentation and responds well to verapamil. Catheter ablation is often curative, making it a manageable condition with a good prognosis.

Source recommendations

1. 2022 American Heart Association (AHA) Guidelines on Ventricular Arrhythmias

1. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001193
2. https://www.sciencedirect.com/science/article/pii/S2405500X22010945
3. https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/algorithms
4. https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/ventricular-fibrillation
5. https://www.jacc.org/doi/10.1016/j.jacc.2024.02.014

2. 2022 European Society of Cardiology (ESC) Guidelines for the Management of Ventricular Arrhythmias

1. https://pubmed.ncbi.nlm.nih.gov/36017572/
2. https://academic.oup.com/eurheartj/article/43/40/3997/6675633
3. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Ventricular-Arrhythmias-and-the-Prevention-of-Sudden-Cardiac-Death
4. https://www.acc.org/Latest-in-Cardiology/ten-points-to-remember/2022/09/02/14/23/2022-ESC-Guidelines-for-VAs-ESC-2022
5. https://www.jacc.org/doi/10.1016/j.jacep.2022.12.008