A patient with Brugada syndrome has recurrent ventricular fibrillation episodes. Current guidelines indicate he should receive an ICD. Which drug, used in the setting of recurrent ICD shocks in Brugada syndrome, acts by blocking transient outward current (Ito) and has demonstrated efficacy in suppressing electrical storms?
- A Amiodarone
- B Flecainide
- C Quinidine ✓
- D Propranolol
Correct answer: C. Quinidine
Explanation
In Brugada syndrome, the pathophysiology involves reduced sodium channel current (SCN5A mutations) with unopposed transient outward current (Ito) causing phase 2 re-entry and VF. Quinidine, which blocks Ito in addition to INa, is the only pharmacological agent with evidence for reducing arrhythmia burden and treating electrical storms in Brugada syndrome; it is a Class IIa recommendation for symptomatic patients or electrical storm. Flecainide, a sodium channel blocker, can paradoxically worsen Brugada. Amiodarone has no proven efficacy. Propranolol is not effective.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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