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Pre-excited AF Management — EECC MCQ

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HardArrhythmia & ElectrophysiologyPre-excited AF ManagementEECC

A 40-year-old man with WPW syndrome (pre-excitation on resting ECG) has an episode of AF with rapid ventricular response via the accessory pathway (pre-excited AF) with minimum RR interval of 190 ms. He is haemodynamically stable. What is the appropriate acute management?

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Correct answer: D — IV procainamide or IV flecainide to block the accessory pathway; AV nodal blocking agents (adenosine, beta-blockers, verapamil, digoxin) are CONTRAINDICATED as they may paradoxically accelerate conduction down the bypass tract causing VF

Pre-excited AF (AF conducting via an accessory pathway) is a life-threatening arrhythmia. The irregular, rapid wide-complex tachycardia can degenerate into VF. AV nodal blocking agents are ABSOLUTELY CONTRAINDICATED because: (1) they do not block the accessory pathway; (2) by blocking AV nodal conduction, they may paradoxically increase conduction exclusively via the bypass tract → faster ventricular rates → VF. CONTRAINDICATED: adenosine, verapamil, diltiazem, beta-blockers, digoxin. APPROPRIATE: (1) IV procainamide (slows accessory pathway conduction — Class I); (2) IV flecainide (blocks accessory pathway); (3) IV amiodarone (mixed effects, may be used with caution); (4) DC cardioversion if haemodynamically unstable or uncertain. DEFINITIVE: catheter ablation of the accessory pathway (curative, >95% success, Class I). The minimum pre-excited RR interval <250 ms (this patient: 190 ms) indicates a high-risk pathway with rapid conduction capability.

Reference: ESC (2019): SVT Guidelines; ESC (2024): AF Guidelines