Previous studies and Rationale: A small randomized study with the old technology that required patient activation for arrhythmia capture found higher diagnostic yield than holter; but the utility was limited due to patients' inability to activate the device after symptoms. Two small studies of unselected syncope patients, one prospective (n=48) and another registry analysis (n=92) found a diagnostic yield 30 - 38% with prolonged monitoring for 7-33 days. The diagnostic yield of holter is 1-20% based on the risk of enrolled patients. The role of prolonged cardiac monitoring among ED syncope patients has not been well studied. Only holter monitoring is being currently used, but inconsistently and is applied a few days later. With the technological advances, the investigators hypothesize that 15-day monitoring will lead to higher diagnostic yield than holter and plan to apply the devices before disposition for high-risk patients discharged home.