skip to main content

Device-detected atrial fibrillation in hypertrophic cardiomyopathy with stable coronary artery disease — ABIM

Instant feedback + full explanation. One question, done properly.

Hard2019Device-detected atrial fibrillation in hypertrophic cardiomyopathy with stable coronary artery diseaseABIM Board

A 67-year-old man with hypertrophic cardiomyopathy undergoes routine interrogation of his dual-chamber implantable cardioverter-defibrillator. The device recorded a 27-hour episode of atrial fibrillation 2 weeks ago; electrograms confirm the diagnosis. He had no symptoms and has no previously recognized atrial fibrillation. His left ventricular ejection fraction is 65%, and he has no mitral stenosis or mechanical heart valve. Three years ago, he underwent drug-eluting stent placement for a non–ST-elevation myocardial infarction. He has had no recurrent ischemic symptoms, repeat coronary intervention, or stent thrombosis and currently takes aspirin and atorvastatin. He has no history of stroke, hypertension, diabetes mellitus, or clinically significant bleeding. His weight is 178 lbs (81 kg), and serum creatinine is 1.1 mg/dL. Which of the following is the most appropriate antithrombotic strategy?

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

Reveal the answer and explanation

Correct answer: A — Discontinue aspirin and start apixaban 5 mg twice daily

Explanation lettering: C = shown as A · A = shown as B · E = shown as C · B = shown as E

This patient should receive full-dose apixaban monotherapy. Hypertrophic cardiomyopathy confers substantial thromboembolic risk from atrial fibrillation that is not adequately represented by the CHA2DS2-VASc score. In patients with HCM, a device-detected atrial fibrillation episode lasting more than 24 hours warrants anticoagulation irrespective of that score, with a direct oral anticoagulant preferred over warfarin. He meets none of the apixaban dose-reduction criteria; reduction to 2.5 mg twice daily requires at least two of age 80 years or older, weight 132 lbs (60 kg) or less, and serum creatinine 1.5 mg/dL or greater. Aspirin alone (A) does not provide adequate prevention of atrial fibrillation–related embolism. Monitoring without treatment (B) is inappropriate because the episode exceeded the 24-hour threshold; shorter device-detected episodes would permit more individualized decision-making. Adding apixaban while continuing aspirin (D) is unnecessary because his coronary disease is stable more than 1 year after PCI and he has no history of stent thrombosis; anticoagulant monotherapy reduces bleeding compared with combined therapy. Warfarin (E) is an effective second-line anticoagulant but is not preferred when a direct oral anticoagulant can be used and there is no mechanical valve or clinically significant mitral stenosis.

Reference: 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy Slide Set (2024) — https://www.heart.org/-/media/PHD-Files-2/Science-News/2/2024/2024-Guideline-for-HCM-Slide-Set.pdf 2023 Guideline for Diagnosis and Management of Atrial Fibrillation: Key Perspectives (2023) — https://www.acc.org/latest-in-cardiology/ten-points-to-remember/2023/11/27/19/46/2023-acc-guideline-for-af-gl-af ELIQUIS (apixaban) Prescribing Information (2026) — https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/220073s001lbl.pdf