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Outcomes of after-hours versus regular working hours primary percutaneous coronary intervention for acute myocardial infarction
  1. Michelle M Graham1,
  2. William A Ghali2,3,4,
  3. Danielle A Southern4,
  4. Mouhieddin Traboulsi2,5,
  5. Merril L Knudtson2,5,
  6. for the APPROACH Investigators
  1. 1Department of Medicine, University of Alberta, Edmonton, Canada
  2. 2Department of Medicine, University of Calgary, Calgary, Canada
  3. 3Department of Community Health Sciences, University of Calgary, Calgary, Canada
  4. 4Centre for Health and Policy Studies, University of Calgary, Calgary, Canada
  5. 5Libin Cardiovascular Institute, University of Calgary, Calgary, Canada
  1. Correspondence to Dr Michelle M Graham, Division of Cardiology, University of Alberta Hospital, 8440-112 Street, Edmonton, Alberta T6G 2R7, Canada; mmg2{at}


Background Primary percutaneous coronary intervention (PCI) is a proven therapy for acute ST-segment elevation myocardial infarction. However, outcomes associated with primary PCI may differ depending on time of day.

Methods and results Using the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease, a clinical data-collection initiative capturing all cardiac catheterisation patients in Alberta, Canada, the authors described and compared crude and risk-adjusted survival for ST-segment elevation myocardial infarction patients undergoing primary PCI after-hours versus regular working hours. From 1 January 1999 to 31 March 2006, 1664 primary PCI procedures were performed (54.4% after-hours). Mortalities at 30 days were 3.6% for regular hours procedures and 5.0% for after-hours procedures (p=0.16). 1-year mortalities were 6.2% and 7.3% in the regular hours and after-hours groups, respectively (p=0.35). After adjusting for baseline risk factor differences, HRs for after-hours mortality were 1.26 (95% CI 0.78 to 2.02) for survival to 30 days and 1.08 (0.73 to 1.59) for survival to 1 year. A meta-analysis of our after-hours HR point estimate with other published risk estimates for after hours primary PCI outcomes yielded an RR of 1.23 (1.00 to 1.51) for shorter-term outcomes.

Conclusions After-hours primary PCI was not associated with a statistically significant increase in mortality. However, a meta-analysis of this study with other published after-hours outcome studies yields an RR that leaves some questions about unexplored factors that may influence after-hours primary PCI care.

  • Infarction
  • mortality
  • angioplasty
  • stents
  • adverse event
  • morbidity and mortality
  • patient outcomes

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  • APPROACH Clinical Steering Committee: Edmonton—R Tsuyuki (chair), M Graham, A Koshal; Calgary—M Curtis, WA Ghali, ML Knudtson, A Maitland, L Brent Mitchell and M Traboulsi.

  • Funding The research and creation of this paper were supported by a grant from the Canadian Institutes of Health Research (CIHR). MLK receives partial support from the Libin Trust Fund. WAG is a Senior Health Scholar of the Alberta Heritage Foundation for Medical Research and also supported by a government of Canada Research Chair in Health Services Research and by a Health Scholar Award from the Alberta Heritage Foundation for Medical Research, Edmonton, Alberta. APPROACH was funded in 1995 by the Weston Foundation, with ongoing support from the Canadian Cardiovascular Outcomes Research Team (CCORT), a CIHR Team Grant and the Province-Wide Services Committee of Alberta Health and Wellness. The initiative has also received unrestricted support from Merck Frosst Canada, Monsanto Canada—Searle, Eli Lilly Canada, Guidant Corporation, Boston Scientific, Hoffmann-La Roche and Johnson & Johnson Inc—Cordis.

  • Competing interests None.

  • Ethics approval Ethics approval was provided by the University of Calgary and University of Alberta.

  • Provenance and peer review Not commissioned; externally peer reviewed.