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Life-threatening haemodynamic instability caused by new-onset atrial fibrillation — MRCEM SBA MCQ

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HardCardiovascular emergenciesLife-threatening haemodynamic instability caused by new-onset atrial fibrillationMRCEM SBA

A 68-year-old man presents with palpitations that began approximately 72 hours ago and worsening breathlessness. An ECG recorded last week showed sinus rhythm. He is now confused, with a blood pressure of 76/48 mmHg, a heart rate of 184/min and bilateral pulmonary crackles. The current ECG shows atrial fibrillation with narrow QRS complexes and no acute ischaemic changes. There is no evidence of sepsis or bleeding. Monitoring, intravenous access, defibrillator pads and resuscitation are in place. He takes no anticoagulant. Which immediate management plan is most appropriate?

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

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Correct answer: C — Perform emergency synchronised electrical cardioversion without delaying for anticoagulation, then continue anticoagulation assessment and monitored care.

The new-onset atrial fibrillation is accompanied by life-threatening haemodynamic instability: profound hypotension, confusion and pulmonary oedema. Emergency synchronised electrical cardioversion takes priority. Although the arrhythmia has lasted more than 48 hours and he is not anticoagulated, NICE specifies that cardioversion must not be delayed to achieve anticoagulation in this situation. Heparin should be offered at initial presentation if there is no contraindication, without postponing the shock; ongoing antithrombotic treatment requires stroke- and bleeding-risk assessment. He needs continued monitoring and assessment after resuscitation. ([nice.org.uk](https://www.nice.org.uk/guidance/ng196/resources/atrial-fibrillation-diagnosis-and-management-pdf-66142085507269)) A applies the three-week anticoagulation requirement for *non-emergency* cardioversion to a patient in shock. B uses a reasonable pathway for selected elective cardioversions after more than 48 hours of AF, but transoesophageal echocardiography would delay treatment of his current instability. D makes pharmacological rhythm control the first intervention despite a need for immediate electrical cardioversion. E treats rate control as the immediate priority; digoxin does not replace emergency cardioversion in life-threatening instability. The distinction is not whether anticoagulation matters, but whether it may delay treatment of shock. ([nice.org.uk](https://www.nice.org.uk/guidance/NG196/chapter/recommendations))

Reference: Atrial fibrillation: diagnosis and management — recommendations (Last updated 30 June 2021) — https://www.nice.org.uk/guidance/NG196/chapter/recommendations Atrial fibrillation: diagnosis and management (NG196) (Guideline last updated 30 June 2021) — https://www.nice.org.uk/guidance/ng196/resources/atrial-fibrillation-diagnosis-and-management-pdf-66142085507269