title: Importance of hospital entry: walk-in STEMI and primary percutaneous coronary intervention.
abstract: BACKGROUND
  Patients with ST elevation myocardial infarction (STEMI) require rapid identification and triage to initiate reperfusion therapy. Walk-in STEMI patients have longer treatment times compared to emergency medical service (EMS) transported patients. While effective triage of large numbers of critically ill patients in the emergency department is often cited as the reason for treatment delays, additional factors have not been explored. The purpose of this study was to evaluate baseline demographic and clinical differences between walk-in and EMS-transported STEMI patients and identify factors associated with prolonged door to balloon (D2B) time in walk-in STEMI patients.
  
  
  METHODS
  We performed a retrospective review of 136 STEMI patients presenting to an urban academic teaching center from January 2009 through December 2010. Baseline demographics, mode of hospital entry (walk-in versus EMS transport), treatment times, angiographic findings, procedures performed and in-hospital clinical events were collected. We compared walk-in and EMS-transported STEMI patients and identified independent factors of prolonged D2B time for walk-in patients using stepwise logistic regression analysis.
  
  
  RESULTS
  Walk-in patients (n=51) were more likely to be Latino and presented with a higher heart rate, higher systolic blood pressure, prior history of diabetes mellitus and were more likely to have an elevated initial troponin value, compared to EMS-transported patients. EMS-transported patients (n=64) were more likely to be white and had a higher prevalence of left main coronary artery disease, compared to walk-in patients. Door to electrocardiogram (ECG), ECG to catheterization laboratory (CL) activation and D2B times were significantly longer for walk-in patients. Walk-in patients were more likely to have D2B time >90 minutes, compared to EMS- transported patients; odds ratio 3.53 (95% CI 1.03, 12.07), p=0.04. Stepwise logistic regression identified hospital entry mode as the only independent predictor for prolonged D2B time.
  
  
  CONCLUSIONS
  Baseline differences exist between walk-in and EMS-transported STEMI patients undergoing primary percutaneous coronary intervention (PCI). Hospital entry mode was the most important predictor for prolonged treatment times for primary PCI, independent of age, Latino ethnicity, heart rate, systolic blood pressure and initial troponin value. Prolonged door to ECG and ECG to CL activation times are modifiable factors associated with prolonged treatment times in walk-in STEMI patients. In addition to promoting the use of EMS transport, efforts are needed to rapidly identify and expedite the triage of walk-in STEMI patients.
authors.affiliation: Division of Cardiovascular Medicine, University of Southern California, Los Angeles, California.
authors.forename: Eric
authors.initials: E
authors.lastname: Bansal
authors.affiliation: Division of Cardiovascular Medicine, University of Southern California, Los Angeles, California.
authors.forename: Rahul
authors.initials: R
authors.lastname: Dhawan
authors.affiliation: Office of Biostatistics and Outcomes Assessment, Los Angeles County + University of Southern California Medical Center, Los Angeles, California.
authors.forename: Brittany
authors.initials: B
authors.lastname: Wagman
authors.affiliation: Office of Biostatistics and Outcomes Assessment, Los Angeles County + University of Southern California Medical Center, Los Angeles, California.
authors.forename: Garren
authors.initials: G
authors.lastname: Low
authors.affiliation: Department of Neurology, University of Southern California, Los Angeles, California.
authors.forename: Ling
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Office of Biostatistics and Outcomes Assessment, Los Angeles County + University of Southern California Medical Center, Los Angeles, California.
authors.forename: Linda
authors.initials: L
authors.lastname: Chan
authors.affiliation: Department of Emergency Medicine, University of Southern California, Los Angeles, California.
authors.forename: Kim
authors.initials: K
authors.lastname: Newton
authors.affiliation: Department of Emergency Medicine, University of Southern California, Los Angeles, California.
authors.forename: Stuart P
authors.initials: SP
authors.lastname: Swadron
authors.affiliation: Department of Emergency Medicine, University of Southern California, Los Angeles, California.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Testa
authors.affiliation: Division of Cardiovascular Medicine, University of Southern California, Los Angeles, California.
authors.forename: David M
authors.initials: DM
authors.lastname: Shavelle
mesh_terms: D000552:Ambulances / Q000706:statistics & numerical data; D006328:Cardiac Catheterization / Q000706:statistics & numerical data; D004562:Electrocardiography / Q000706:statistics & numerical data; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000601:surgery*; D062645:Percutaneous Coronary Intervention / Q000706:statistics & numerical data*; D013997:Time Factors