OBJECTIVES: Anti-platelet therapy is recommended for patients with a history of acute coronary syndrome (ACS), including aspirin and clopidogrel or prasugrel.  Ticagrelor is a new anti-platelet agent, not yet available on the market; in clinical trials ticagrelor was associated with significantly higher rates of dyspnea than clopidogrel.  ACS patients presenting with dyspnea require additional medical attention to rule out possible heart failure which may lead to increased costs.  This study used real world data to quantify the direct medical costs of dyspnea among patients with a history of ACS. METHODS: Patients with an emergency room (ER) visit for dyspnea (ICD-9-CM 786.0x) in 2008 or 2009 were identified using the MarketScan Research Databases®.  Patients were required to have six months continuous medical enrollment prior to the ER visit, with a history of ACS (ICD-9-CM 410.xx, 411.1x).  Procedure utilization and expenditures were evaluated for the ER visit and associated outpatient services, as well as the proportion of ER visits which led to an inpatient stay.  Costs were adjusted to 2009 US dollars.  RESULTS: A total of 8,433 ER visits for dyspnea were identified.  The average cost per dyspnea episode was $6,958, of which $1,621 was outpatient costs associated with the ER visit (SD= $3,269). Along with  physician services, assessment of dyspnea often included electrocardiogram (71.3%), chest radiograph (75.9%) and, occasionally, a B-type natriuretic peptide (BNP) test (14.9%) or chest CAT scan (12.2%).  These procedures constituted 35.1% of the average outpatient costs.  Over a quarter (25.8%) of dyspnea ER visits led to an inpatient stay, with an average cost of $20,693 per patient. CONCLUSIONS: Dyspnea is a significant event associated with high medical resource utilization and hospital costs.  Considering that the increased risk of dyspnea for ticagrelor is well-documented, these costs may be important to health plan decision makers when evaluating costs associated with each anti-platelet therapy.