title: Triggering of acute myocardial infarction by respiratory infection.
abstract: BACKGROUND
  Respiratory infection has been associated with an increased short-term risk of myocardial infarction (MI). However, previous studies have predominantly been conducted without angiographic confirmation of MI. The possibility can therefore not be excluded that raised troponin levels or electrocardiogram abnormalities that may be seen with respiratory infections are due to non-ischaemic causes.
  
  
  OBJECTIVE
  To investigate the association between respiratory infection and angiographically confirmed MI.
  
  
  METHODS
  Interviews were conducted within 4 days of hospitalisation in 578 patients with angiographically confirmed MI, to assess for recent exposure to respiratory infection symptoms and the usual annual frequency of these symptoms. Using case-crossover methodology, exposure to respiratory infection prior to the onset of MI was compared against the usual frequency of exposure in the past year.
  
  
  RESULTS
  Symptoms of respiratory infection were reported by 100 (17%) and 123 (21%) within 7 and 35 days, respectively, prior to MI. The relative risk (RR) for MI occurring within 1-7 days after respiratory infection symptoms was 17.0 (95% confidence interval (CI) 13.2-21.8), and declined with subsequent time periods. In a subgroup analysis, the RR tended to be lower in groups taking regular cardiac medications. For those who reported milder, upper respiratory tract infection symptoms, the RR for the 1-7-day time period was 13.5 (95% CI 10.2-17.7).
  
  
  CONCLUSIONS
  These findings confirm that respiratory infection can trigger MI. Further study is indicated to identify treatment strategies to decrease this risk, particularly in individuals who may have increased susceptibility.
authors.affiliation: Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Lorcan
authors.identifier: http://orcid.org/0000-0003-2087-8091
authors.initials: L
authors.lastname: Ruane
authors.affiliation: Sydney Nursing School, University of Sydney, Sydney, New South Wales, Australia.|Cardiology Department, Royal North Shore Hospital, Sydney, New South Wales, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Buckley
authors.affiliation: Cardiology Department, Royal North Shore Hospital, Sydney, New South Wales, Australia.
authors.forename: Soon Y S
authors.initials: SYS
authors.lastname: Hoo
authors.affiliation: Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.|Cardiology Department, Royal North Shore Hospital, Sydney, New South Wales, Australia.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hansen
authors.affiliation: Sydney Nursing School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Catherine
authors.initials: C
authors.lastname: McCormack
authors.affiliation: Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.|Cardiology Department, Royal North Shore Hospital, Sydney, New South Wales, Australia.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Shaw
authors.affiliation: Sydney Nursing School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Judith
authors.initials: J
authors.lastname: Fethney
authors.affiliation: Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.|Cardiology Department, Royal North Shore Hospital, Sydney, New South Wales, Australia.
authors.forename: Geoffrey H
authors.initials: GH
authors.lastname: Tofler
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015985:Precipitating Factors; D012141:Respiratory Tract Infections / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D012307:Risk Factors
keywords: angiography; epidemiology; infection; myocardial infarction; risk factor