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Atrial fibrillation with instability — ABEM Board MCQ

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EasyCardiovascular emergenciesAtrial fibrillation with instabilityABEM Board

A 72-year-old woman arrives with palpitations, chest pressure, and near-syncope. Triage acuity is ESI 1; BP 78/46 mm Hg, HR 168/min irregularly irregular, RR 24/min. She is pale and confused, with cool extremities and no signs of trauma. ECG shows atrial fibrillation with rapid ventricular response. Which of the following is the most appropriate initial action?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Perform immediate synchronized cardioversion

Unstable tachyarrhythmia with hypotension and altered mental status requires synchronized cardioversion rather than rate-control medication.

Reference: AHA ACLS 2025 tachycardia algorithm