The symptom-disease pair analysis of diagnostic error approach, or SPADE approach, measures diagnostic errors resulting in adverse events using two analytic pathways – the ‘look back’ analysis identifies symptoms associated with adverse events and identifies the symptom-specific harm rate per hospitalization and the ‘look forward’ analysis measures the disease-specific harm rate per symptomatic discharge. Using data from 2009 to 2017, this retrospective analysis looked at Emergency Department (ED) visits within 30 days of a hospitalization for acute myocardial infarction (AMI) to identify symptoms linked to probable missed diagnoses. Within 30 days of a subsequent hospitalization for AMI, common ED discharge diagnoses included chest pain and dyspnea, representing 574 probable missed AMIs. The authors estimate that these results correspond to approximately 10,000 potentially-preventable harms annually in the United States.