Haemodynamically unstable new-onset atrial fibrillation — MRCEM SBA MCQ

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EasyCardiovascular emergenciesHaemodynamically unstable new-onset atrial fibrillationMRCEM SBA

A 68-year-old woman presents to the emergency department two hours after the sudden onset of palpitations and breathlessness. She has no history of atrial fibrillation. Her ECG shows an irregular narrow-complex tachycardia at 182/min with no discernible P waves. She is now confused and clammy, with a blood pressure of 74/46 mmHg. There is no evidence of bleeding or infection. Cardiac monitoring and intravenous access are established. What is the most appropriate immediate intervention?

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Correct answer: E — Immediate synchronised electrical cardioversion

The irregular narrow-complex rhythm without discernible P waves indicates atrial fibrillation. Profound hypotension, confusion and poor peripheral perfusion indicate life-threatening haemodynamic instability attributable to the rapid arrhythmia. NICE recommends emergency electrical cardioversion in this situation **without delaying to achieve anticoagulation**; the shock is synchronised because she has a pulse. Anticoagulation and stroke-risk assessment remain important after immediate stabilisation, and she requires continued monitoring and senior review. ([nice.org.uk](https://www.nice.org.uk/guidance/NG196/chapter/recommendations)) **A** may attract candidates seeking rapid rate control, but intravenous beta-blockade is not the priority in shock and could worsen hypotension. **B** is a plausible rhythm-control treatment for selected patients without life-threatening instability, but must not delay cardioversion here. **C** reflects the anticoagulation required before *elective* cardioversion in some stable patients, particularly when atrial fibrillation has lasted more than 48 hours; it does not apply to this emergency. **D** may be considered for rate control in selected stable patients, but is not an appropriate immediate response to this degree of circulatory compromise. ([nice.org.uk](https://www.nice.org.uk/guidance/NG196/chapter/recommendations))

Reference: Atrial fibrillation: diagnosis and management, recommendations 1.8.1–1.8.8 (Last updated 30 June 2021) — https://www.nice.org.uk/guidance/NG196/chapter/recommendations Atrial fibrillation guidance: AF with Haemodynamic Compromise (Published circa 2019) — https://www.whittington.nhs.uk/document.ashx?id=6034