Cryptogenic stroke (CS) represents 10%–40% of ischemic strokes and is associated with significant morbidity and mortality and high risk of recurrence. Undetected atrial fibrillation is an important consideration in these patients. Tools for electrocardiographic monitoring range from 12-lead electrocardiogram to implantable loop recorders (ILRs). ILRs have become an important tool for long-term electrocardiogram monitoring in CS patients. Advancements in ILR technology are needed to ensure more robust connectivity and to help triage incoming data. An unresolved issue is what duration of AF indicates that the CS patient is at high risk for recurrent stroke and thus would benefit from initiation of anticoagulation.