title: Association between clinical presentations before myocardial infarction and coronary mortality: a prospective population-based study using linked electronic records.
abstract: BACKGROUND
  Ischaemia in different arterial territories before acute myocardial infarction (AMI) may influence post-AMI outcomes. No studies have evaluated prospectively collected information on ischaemia and its effect on short- and long-term coronary mortality. The objective of this study was to compare patients with and without prospectively measured ischaemic presentations before AMI in terms of infarct characteristics and coronary mortality.
  
  
  RESULTS
  As part of the CALIBER programme, we linked data from primary care, hospital admissions, the national acute coronary syndrome registry and cause-specific mortality to identify patients with first AMI (n = 16,439). We analysed time from AMI to coronary mortality (n = 5283 deaths) using Cox regression (median 2.6 years follow-up), comparing patients with and without recent ischaemic presentations. Patients with ischaemic presentations in the 90 days before AMI experienced lower coronary mortality in the first 7 days after AMI compared with those with no prior ischaemic presentations, after adjusting for age, sex, smoking, diabetes, blood pressure and cardiovascular medications [HR: 0.64 (95% CI: 0.57-0.73) P < 0.001], but subsequent mortality was higher [HR: 1.42 (1.13-1.77) P = 0.001]. Patients with ischaemic presentations closer in time to AMI had the lowest seven day mortality (P-trend = 0.001).
  
  
  CONCLUSIONS
  In the first large prospective study of ischaemic presentations prior to AMI, we have shown that those occurring closest to AMI are associated with lower short-term coronary mortality following AMI, which could represent a natural ischaemic preconditioning effect, observed in a clinical setting.
  
  
  BACKGROUND
  Clinicaltrials.gov identifier NCT01604486.
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK emily.herrett@lshtm.ac.uk.
authors.forename: Emily
authors.initials: E
authors.lastname: Herrett
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Bhaskaran
authors.affiliation: Barts and the London School of Medicine and Dentistry, London, UK Farr Institute of Health Informatics Research, London, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Timmis
authors.affiliation: University College London, London, UK Farr Institute of Health Informatics Research, London, UK.
authors.forename: Spiros
authors.initials: S
authors.lastname: Denaxas
authors.affiliation: University College London, London, UK Farr Institute of Health Informatics Research, London, UK.
authors.forename: Harry
authors.initials: H
authors.lastname: Hemingway
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK Farr Institute of Health Informatics Research, London, UK.
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000787:Angina Pectoris / Q000150:complications / Q000401:mortality; D050197:Atherosclerosis / Q000150:complications / Q000401:mortality; D002317:Cardiovascular Agents / Q000627:therapeutic use; D002561:Cerebrovascular Disorders / Q000150:complications / Q000401:mortality; D057286:Electronic Health Records; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007511:Ischemia / Q000150:complications / Q000401:mortality*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality*; D058729:Peripheral Arterial Disease / Q000150:complications / Q000401:mortality; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D002317:Cardiovascular Agents
keywords: Epidemiology; Ischaemia; Myocardial infarction