title: Time of day variation in door-to-balloon time for STEMI patients in Los Angeles County: does time of day make a difference?
abstract: OBJECTIVE
  Evaluate treatment times and clinical outcome in a consecutive series of ST segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI) in Los Angeles County.
  
  
  BACKGROUND
  Primary PCI for STEMI is beneficial if performed in a timely manner. Conflicting data exist regarding potential treatment delays for primary PCI performed during off hours.
  
  
  METHODS
  The Emergency Medical Services STEMI Receiving Center Database was queried from 2007 to 2009 to identify patients with a pre-hospital ECG showing STEMI who underwent PCI. On-hour PCI (On-hour Group, n = 1324) was defined as PCI occurring from 8 am to 5 pm and off-hour PCI (Off-hour Group, n = 922) was defined as occurring from 5 pm to 8 am. Treatment times, length of stay, vascular complications, achievement of TIMI 3 flow and in-hospital mortality were evaluated.
  
  
  RESULTS
  Off-hours PCI occurred in 41% of patients. Medical contact to door time was similar in the Off-hour Group compared to the On-hour Group, 20.7 ± 14.6 versus 20.3 ± 12.3 min, respectively, P = 0.47. In patients with available data (n = 1366), the door-to-catheterization laboratory (CL) activation time was significantly shorter in the On-hour Group as compared to the Off-hour Group, -4.9 ± 11.9 versus -0.2 ± 27.5 min, respectively, P < 0.0001. Door-to-balloon time was significantly longer in the Off-hour Group compared to the On-hour Group, 74 ± 35 versus 60 ± 26 min respectively, P < 0.0001. Length of stay, vascular complications, final TIMI 3 flow and in-hospital mortality were similar between both groups.
  
  
  CONCLUSIONS
  In STEMI patients receiving primary PCI in Los Angeles County, off-hour PCI was common. Short-term clinical outcomes were similar despite longer door-to-balloon time in patients receiving off-hour PCI. The longer door-to-balloon time in the off-hour PCI patients were partly explained by longer door-to-CL activation time.
authors.affiliation: Division of Cardiovascular Medicine, University of Southern California, Los Angeles, 90033, USA. shavelle@usc.edu
authors.forename: David M
authors.initials: DM
authors.lastname: Shavelle
authors.forename: Ling
authors.initials: L
authors.lastname: Zheng
authors.forename: Marcus
authors.initials: M
authors.lastname: Ottochian
authors.forename: Brittany
authors.initials: B
authors.lastname: Wagman
authors.forename: Nicholas
authors.initials: N
authors.lastname: Testa
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hall
authors.forename: William
authors.initials: W
authors.lastname: Koenig
authors.forename: Linda S
authors.initials: LS
authors.lastname: Chan
authors.forename: Ray V
authors.initials: RV
authors.lastname: Matthews
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D004562:Electrocardiography; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay; D015141:Los Angeles; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality / Q000601:surgery*; D061665:Time-to-Treatment; D016896:Treatment Outcome