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Unstable atrial fibrillation — SCE Acute Medicine MCQ

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EasyAcute Cardiac PresentationsUnstable atrial fibrillationSCE Acute Medicine

A 68-year-old man develops sudden palpitations and severe breathlessness on the AMU. ECG shows atrial fibrillation at 168/min. Blood pressure is 78/50 mmHg, he is clammy and oxygen saturation is 91% on air. He has no known anticoagulation and symptom onset was one hour ago. What is the most important immediate action?

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Correct answer: B — Synchronised electrical cardioversion

Atrial fibrillation with shock is an unstable tachyarrhythmia requiring urgent synchronised DC cardioversion. Rate-control drugs such as beta-blockers or verapamil can worsen hypotension in this setting. Anticoagulation should be considered, but instability takes priority. The teaching point is that haemodynamic status determines immediate arrhythmia management.

Reference: Resuscitation Council UK ALS; NICE NG196