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Atrial fibrillation stroke prevention — MCCQE Part 1 MCQ

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HardPalpitationsAtrial fibrillation stroke preventionMCCQE Part 1

A 32-year-old has abrupt palpitations. ECG shows a regular narrow-complex tachycardia at 184/min. BP is 122/76 mm Hg; she is alert without chest pain, heart failure, or shock. A properly performed modified Valsalva manoeuvre fails. She has no asthma and has not had a heart transplant. What should be done next?

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Correct answer: B — Give rapid intravenous adenosine with continuous monitoring and resuscitation capability

This is a stable, regular narrow-complex tachycardia. After an effective vagal manoeuvre fails, rapid intravenous adenosine is the appropriate next diagnostic and therapeutic intervention, delivered with ECG monitoring and immediate resuscitation capability. Its very short half-life means a rapid push and flush are required. Adenosine can terminate AV-nodal re-entry or transiently reveal another atrial rhythm. It can cause flushing, chest discomfort, or bronchospasm and is contraindicated in severe asthma; smaller initial doses may be appropriate after heart transplant or through a central line. If hypotension, altered mental status, ischaemic chest pain, shock, or acute heart failure develops because of the rhythm, synchronized cardioversion becomes the priority. Defibrillation and chest compressions are for pulseless or specific shockable emergencies, not this perfusing patient.

Reference: American Heart Association, 2025 Adult Advanced Life Support: https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/adult-advanced-life-support