Clinical features

• any nausea or vomiting before collapse ^a

Why?

Lack of nausea and vomiting increases the risk of an arrhythmia

Patient	Prognostic Factor	Outcome	CER	RR (95% CI)	NNF+ (95% CI)
unexplained syncope a	absence of nausea or vomiting before syncope independent	syncope due to cardiac arrhythmia at 12 months	20%	7.1 (1.6 to 33.3)	2 (1 to 12)