The effect of different antithrombotic regimens on platelet aggregation after myocardial infarction.
Platelet aggregate ratio (PAR) was measured according to the method of Wu & Hoak in 143 patients after acute myocardial infarction (AMI) and in 54 controls. A PAR < 1 expresses the presence of platelet aggregates. The patients were randomized to aspirin 160 mg/d, or warfarin, or aspirin 75 mg/d + warfarin. In patients on aspirin, PAR was measured 24 h after aspirin intake, and in 76 patients also 2 h after aspirin. The median PAR in patients on warfarin was 0.85, on warfarin + aspirin 0.91 and on aspirin alone 0.94, all significantly lower than the median PAR of 0.97 in the controls. In 14 patients on aspirin the PARs were below a cut-off point of 0.82 (secondary aspirin non-responders). PAR increase significantly 2 h after aspirin intake. In two patients, however, PAR remained low (primary aspirin non-responders). It is concluded that some patients do not seem to respond to aspirin, the clinical implication of which has yet to be determined.
Hurlen
M
M
Department of Cardiology, Ullevål University Hospital, Oslo, Norway.
Seljeflot
I
I
Arnesen
H
H
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000925:Anticoagulants / Q000008:administration & dosage*; D001241:Aspirin / Q000008:administration & dosage*; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D012044:Regression Analysis; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage*
D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014859:Warfarin; D001241:Aspirin