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Hyperkalemia ECG changes — USMLE Step 3 MCQ

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HardEmergency MedicineHyperkalemia ECG changesUSMLE Step 3

A 76-year-old man with hypertension and a prior transient ischemic attack has a dual-chamber pacemaker. Interrogation confirms an 11-hour atrial high-rate episode consistent with atrial fibrillation; no episode has reached 24 hours, and he has never had atrial fibrillation on a surface ECG. He has no major bleeding risk. Which approach best reflects current guideline guidance?

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Correct answer: B — Use shared decision-making to consider starting a direct oral anticoagulant now

The best answer is “Use shared decision-making to consider starting a direct oral anticoagulant now”. The confirmed episode lasts between 5 minutes and 24 hours, and the CHA2DS2-VASc score is 5. The 2023 ACC/AHA/ACCP/HRS guideline states that anticoagulation may be reasonable in this duration range when the score is at least 3, within shared decision-making that accounts for episode duration, stroke risk, bleeding risk, and uncertainty. A 24-hour minimum and surface-ECG confirmation are not required, but the conditional recommendation should not be presented as mandatory.

Reference: 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: https://professional.heart.org/-/media/Files/Professional/Quality-Improvement/Get-With-the-Guidelines/Get-With-The-Guidelines-AFIB/AFib-Month/joglaretal20232023areportofaccahaaccphrsguidelineforthediagnosisandmanagementofatrialfibrillation.pdf