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Unstable complete heart block — SCE Acute Medicine MCQ

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ModerateAcute Cardiac PresentationsUnstable complete heart blockSCE Acute Medicine

An 81-year-old man collapses on the ward. ECG shows complete heart block with a ventricular rate of 28 bpm and broad QRS escape rhythm. BP is 74/42 mmHg despite atropine 500 micrograms IV. Potassium is 4.6 mmol/L and he is not taking beta-blockers. What is the most appropriate next step in management?

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Correct answer: E — Arrange urgent transcutaneous pacing while preparing transvenous pacing

Complete heart block with shock and broad QRS escape is a peri-arrest bradyarrhythmia requiring pacing when atropine is ineffective. Repeated atropine alone is insufficient when life-threatening features persist. Verapamil and flecainide can worsen conduction disease. The practical point is to treat reversible causes but not to delay pacing in unstable high-grade block.

Reference: Resuscitation Council UK bradycardia algorithm, BNF