<keypoints>
- **Cardiac red flags** are the most critical: syncope during exertion, while supine, with palpitations or chest pain, or family history of sudden cardiac death
- **Historical red flags**: age >65, known structural/coronary heart disease, known arrhythmia, severe anaemia, sudden onset headache, known AAA
- **Clinical red flags**: altered consciousness, persistent hypotension, cardiac arrhythmia, abdominal distension/rigidity, suspected PE or GI bleed, head injury
- High-risk patients should be admitted for further evaluation; low-risk patients with a single episode can often be reassured
</keypoints>
Historical Red Flags
The NSW ACI ECAT protocol identifies the following historical red flags:
- Age >65 years
- Structural or coronary heart disease
- Known abdominal aortic aneurysm (AAA)
- Syncope during exertion, while supine or sitting
- Palpitations prior to syncope
- Family history of sudden cardiac death
- Severe anaemia
- Known cardiac arrhythmia or cardiac history
- Sudden onset headache
The 2017 ACC/AHA/HRS guideline adds:
- Male sex
- Brief or absent prodrome (sudden loss of consciousness without warning)
- Low number of episodes (1 or 2, suggesting a new cardiac cause)
- Reduced ventricular function
- Family history of inheritable conditions or premature sudden cardiac death (<50 years of age)
- Known congenital heart disease