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Cryptogenic Stroke – ILR-Detected AF — SCE Neurology MCQ

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ModerateCerebrovascular DiseaseCryptogenic Stroke – ILR-Detected AFSCE Neurology

A 65-year-old man with a cryptogenic ischaemic stroke undergoes extended cardiac monitoring with an implantable loop recorder (ILR). After 12 months, atrial fibrillation is detected on 3 separate occasions, each lasting >30 seconds. What is the clinical significance?

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Correct answer: D — Subclinical AF detected by prolonged monitoring after cryptogenic stroke justifies anticoagulation for secondary prevention

The CRYSTAL-AF trial demonstrated that prolonged cardiac monitoring with ILR detects significantly more AF than conventional monitoring in cryptogenic stroke patients. Detection of AF (typically defined as episodes >30 seconds to 2 minutes, though definitions vary) after cryptogenic stroke justifies anticoagulation for secondary prevention, as the AF is presumed to be the stroke mechanism. DOACs are preferred over warfarin. A: Even short episodes of AF can cause cardioembolism. C: Modern ILRs have high AF detection accuracy. D: AF has been detected — treatment should not be delayed. E: Shorter episodes are now considered clinically relevant.

Reference: CRYSTAL-AF Trial (2014); NICE NG128; ESC AF Guidelines (2024)