A 58-year-old man with a history of anterior wall myocardial infarction presents with recurrent episodes of palpitations. His 12-lead ECG shows wide QRS complexes (120 ms) with a left bundle branch block pattern and AV dissociation. Regarding the mechanisms and management of ventricular arrhythmias, all of the following statements are correct EXCEPT:

Question

A 58-year-old man with a history of anterior wall myocardial infarction presents with recurrent episodes of palpitations. His 12-lead ECG shows wide QRS complexes (>120 ms) with a left bundle branch block pattern and AV dissociation. Regarding the mechanisms and management of ventricular arrhythmias, all of the following statements are correct EXCEPT:

Accepted Answer

D. Amiodarone is the first-line antiarrhythmic agent for acute termination of hemodynamically unstable ventricular fibrillation in the absence of a defibrillator. ## Analysis of Ventricular Arrhythmia Management

### Correct Statements (Options 0, 1, 2)

**Key Point:** AV dissociation is a hallmark finding in ventricular tachycardia, confirming independent atrial and ventricular rhythms and proving ventricular origin of the arrhythmia.

**Key Point:** Brugada syndrome is an autosomal-dominant channelopathy (SCN5A mutation) presenting with characteristic ECG findings (coved ST elevation in V1–V3) and high sudden cardiac death risk despite structurally normal hearts.

**Key Point:** Long QT syndrome (both congenital and acquired) causes QT prolongation and predisposes to Torsades de Pointes, a polymorphic VT often triggered by auditory stimuli (Jervell and Lange-Nielsen syndrome) or emotional/physical stress.

### Incorrect Statement (Option 3 — Correct Answer)

**High-Yield:** In acute ventricular fibrillation, **unsynchronized electrical defibrillation (not antiarrhythmic drugs) is the definitive first-line treatment**. Amiodarone is used as an *adjunct* after failed defibrillation attempts (per ACLS guidelines), not as the primary intervention. Immediate defibrillation within 3–5 minutes is critical for survival.

**Clinical Pearl:** The hierarchy for VF is: (1) Immediate CPR, (2) Defibrillation (first shock), (3) Amiodarone only if VF persists after 2–3 defibrillation attempts.

### Summary Table

| Feature | Brugada | Long QT | Catecholaminergic CPVT |
|---------|---------|---------|------------------------|
| ECG Finding | ST ↑ V1–V3 | QT ↑ | Normal at rest |
| Trigger | Fever, rest | Auditory, emotion | Exercise, emotion |
| Arrhythmia | VF | Torsades | Bidirectional VT |
| Genetics | SCN5A (Na^+^) | KCNQ1, KCNH2 (K^+^) | RYR2, CASQ2 (Ca^2+^) |

Answer

A. Ventricular tachycardia with AV dissociation is pathognomonic for a ventricular origin of the arrhythmia

Answer

B. Long QT syndrome predisposes to polymorphic ventricular tachycardia (Torsades de Pointes) triggered by sudden auditory stimuli or emotional stress

Answer

C. Brugada syndrome is characterized by spontaneous ST-segment elevation in leads V1–V3 and an increased risk of sudden cardiac death in structurally normal hearts

Explanation

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