title: TIMI risk index and the benefit of enoxaparin in patients with ST-elevation myocardial infarction.
abstract: OBJECTIVE
  The purpose of the study was to evaluate the cause of death, risk of nonfatal complications, and relative outcomes with an enoxaparin versus unfractionated heparin strategy in ST-elevation myocardial infarction stratified using the Thrombolysis in Myocardial Infarction (TIMI) Risk Index (TRI).
  
  
  METHODS
  We evaluated 30-day outcomes in 19,941 patients with ST-elevation myocardial infarction treated with fibrinolysis and unfractionated heparin or enoxaparin. Patients were categorized on the basis of prespecified ranges of the TRI [heart rate x (age/10)2/systolic blood pressure].
  
  
  RESULTS
  There was a strongly graded increase in 30-day mortality with increasing TRI (1.2%-20.7%, P<.0001). The proportion of deaths due to mechanical causes (congestive heart failure, shock, and myocardial rupture) increased progressively with the TRI. There also was a significant positively graded association between the TRI and nonfatal heart failure or shock (0.4%-4.4%, P<.0001). In contrast, death resulting from recurrent ischemic events predominated in the lowest TRI group. The relative reduction in death/myocardial infarction with the enoxaparin strategy appeared inversely graded with the TRI. There was a 38% reduction in the lowest risk group (relative risk 0.62, 95% confidence interval 0.45-0.86) and a decrease in the relative benefit of enoxaparin with increasing risk index.
  
  
  CONCLUSIONS
  The TRI was a strong predictor of all-cause mortality in a broad population, with a positive association with the risk of death due to mechanical complications and an inverse association with deaths due to recurrent ischemia. The enoxaparin strategy was superior to unfractionated heparin in a majority of patients with ST-elevation myocardial infarction, except for the group at the highest risk for severe mechanical complications, in whom the 2 anticoagulant strategies showed similar results.
authors.affiliation: TIMI Study Group, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass 02115, USA. cruff@partners.org
authors.forename: Christian T
authors.initials: CT
authors.lastname: Ruff
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Wiviott
authors.forename: David A
authors.initials: DA
authors.lastname: Morrow
authors.forename: Satishkumar
authors.initials: S
authors.lastname: Mohanavelu
authors.forename: Sabina A
authors.initials: SA
authors.lastname: Murphy
authors.forename: Elliott M
authors.initials: EM
authors.lastname: Antman
authors.forename: Eugene
authors.initials: E
authors.lastname: Braunwald
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac; D002423:Cause of Death; D017984:Enoxaparin / Q000008:administration & dosage / Q000627:therapeutic use*; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006470:Hemorrhage; D006493:Heparin / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy*; D012307:Risk Factors
chemical_list: D017984:Enoxaparin; D005343:Fibrinolytic Agents; D006493:Heparin