Timing continued:

• Surveys of young adults have shown that around 50% will report having at least one episode of loss of consciousness. Most of these never come to medical attention because they are isolated events. The average is three to five episodes before seeking medical care.
• Note the time intervals between episodes. A 24-hour Holter will be useless, and might show some irrelevant arrhythmia (e.g., PVCS), which could lead you in the wrong direction. In all forms of syncope but one (syncope in patients with known HCM), Holter monitoring is relatively worthless.