Score < 0 associated with < 2% risk of serious adverse event at 30 days.
Externally validated per data presented at SAEM 2018 and only 0.3% 30 day adverse events for very low risk patients in 2020 Jama study 
1.4% of patients who are rule-negative will have a 7-day serious outcome
10% of patients meeting the below criteria will have a 7-day serious outcome
CHF History
Hct < 30%
ECG Abnormality
SOB history
SBP < 90mmHg at triage
Performed poorly on external validation
External validation of San Francisco<unk>  Rule showed sensitivity 90% but only specificity of 33%
Syncope
Cardiovascular-mediated syncope
Laryngospasm
Dysrhythmias:
Chest pain 
WPW 
Sedation 
Long QT Syndrome/QT prolongation