title: A randomized comparison of intravenous heparin with oral aspirin and dipyridamole 24 hours after recombinant tissue-type plasminogen activator for acute myocardial infarction. National Heart Foundation of Australia Coronary Thrombolysis Group.
abstract: BACKGROUND
  This study addressed the need for heparin administration to be continued for more than 24 hours after coronary thrombolysis with recombinant tissue-type plasminogen activator (rt-PA).
  
  
  RESULTS
  A total of 241 patients with acute myocardial infarction were treated with 100 mg rt-PA and a bolus of 5,000 units i.v. heparin followed by 1,000 units/hr i.v. heparin for 24 hours. At 24 hours, 202 patients were randomized to continue intravenous heparin therapy (n = 99) in full dosage or to discontinue heparin therapy and begin an oral antiplatelet regimen of aspirin (300 mg/day) and dipyridamole (300 mg/day) (n = 103). On prospective recording, there were no differences in the pattern of chest pain, reinfarction, or bleeding complications. Coronary angiography on cardiac catheterization at 7-10 days showed no differences in patency of the infarct-related artery. The proportion of patients with total occlusion (TIMI grade 0-1) of the infarct-related artery was 18.9% in the heparin group and 19.8% in the aspirin and dipyridamole group. In the patients with an incompletely occluded infarct-related artery, the lumen was reduced by 69 +/- 2% of normal in the heparin group and 67 +/- 2% in the aspirin and dipyridamole group. Left ventricular function assessed on cardiac catheterization and radionuclide study at day 2 and at 1 month showed no differences between the two groups. Left ventricular ejection fraction on radionuclide ventriculography at 1 month was 52.4 +/- 1.2% in the heparin group and 51.9 +/- 1.2% in the aspirin and dipyridamole group.
  
  
  CONCLUSIONS
  We conclude that heparin therapy can be discontinued 24 hours after rt-PA therapy and replaced with an oral antiplatelet regimen without any adverse effects on chest pain, reinfarction, coronary patency, or left ventricular function.
authors.affiliation: Sir Charles Gairdner Hospital, Perth, Australia.
authors.forename: P L
authors.initials: PL
authors.lastname: Thompson
authors.forename: P E
authors.initials: PE
authors.lastname: Aylward
authors.forename: J
authors.initials: J
authors.lastname: Federman
authors.forename: R W
authors.initials: RW
authors.lastname: Giles
authors.forename: P J
authors.initials: PJ
authors.lastname: Harris
authors.forename: R L
authors.initials: RL
authors.lastname: Hodge
authors.forename: G I
authors.initials: GI
authors.lastname: Nelson
authors.forename: A
authors.initials: A
authors.lastname: Thomson
authors.forename: A M
authors.initials: AM
authors.lastname: Tonkin
authors.forename: W F
authors.initials: WF
authors.lastname: Walsh
mesh_terms: D000284:Administration, Oral; D000925:Anticoagulants / Q000008:administration & dosage* / Q000627:therapeutic use; D001241:Aspirin / Q000008:administration & dosage / Q000627:therapeutic use; D004176:Dipyridamole / Q000008:administration & dosage / Q000627:therapeutic use; D005260:Female; D006493:Heparin / Q000008:administration & dosage* / Q000627:therapeutic use; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy*; D011994:Recombinant Proteins; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*; D014654:Vascular Patency / Q000187:drug effects
chemical_list: D000925:Anticoagulants; D011994:Recombinant Proteins; D004176:Dipyridamole; D006493:Heparin; D010959:Tissue Plasminogen Activator; D001241:Aspirin