title: Time-dependent effect of preinfarction angina pectoris and intermittent claudication on mortality following myocardial infarction: A Danish nationwide cohort study.
abstract: BACKGROUND
  As proxies for local and remote ischemic preconditioning, we examined whether preinfarction angina pectoris and intermittent claudication influenced mortality following myocardial infarction.
  
  
  METHODS
  Using medical registries, we conducted a nationwide population-based cohort study of all first-time myocardial infarction patients in Denmark during 2004-2012 (n=70,458). We computed all-cause and coronary mortality rate ratios (MRRs). We categorized time between angina/claudication presentation and subsequent myocardial infarction as 0-14, 15-30, 31-90, and > 90 days. We adjusted for age, sex, coronary intervention, comorbidities, and medication use.
  
  
  RESULTS
  Among all myocardial infarction patients, 18.4% had prior angina and 3.8% had prior intermittent claudication. Compared to patients without prior angina, the adjusted 30-day coronary MRR was 0.85 (95% confidence interval (CI): 0.80-0.92) for stable and 0.68 (95% CI: 0.58-0.79) for unstable angina patients. The mortality reduction increased when angina presented close to myocardial infarction and was higher for unstable than for stable angina. Thus, the 30-day coronary MRR was 0.72 (95% CI: 0.51-1.02) for stable angina and 0.35 (95% CI: 0.17-0.73) for unstable angina presenting within 14 days before MI. The results were robust for all-cause mortality and in numerous subgroups, including women, diabetics, patients treated with PCI, and patients treated with and without cardioprotective drugs. Preinfarction intermittent claudication was associated with higher short- and long-term mortality compared to patients without intermittent claudication.
  
  
  CONCLUSIONS
  Preinfarction angina reduced 30-day mortality, particularly when unstable angina closely preceded MI. Preinfarction intermittent claudication was associated with increased short- and long-term mortality.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark; Department of Cardiology, Aarhus University Hospital, Skejby, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark. Electronic address: morten.schmidt@clin.au.dk.
authors.forename: Morten
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark.
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Horváth-Puhó
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark.
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark.
authors.forename: Hans Erik
authors.initials: HE
authors.lastname: Bøtker
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060050:Angina, Stable / Q000150:complications / Q000401:mortality; D000789:Angina, Unstable / Q000150:complications / Q000401:mortality*; D015331:Cohort Studies; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000150:complications / Q000401:mortality; D003718:Denmark / Q000453:epidemiology; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007383:Intermittent Claudication / Q000150:complications* / Q000401:mortality*; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods; D008297:Male; D008875:Middle Aged; D009026:Mortality; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality*; D012042:Registries
keywords: Angina pectoris; Intermittent claudication; Ischemic preconditioning; Mortality; Myocardial infarction