Flowcytometric evidence of platelet activation in patients on aspirin following myocardial infarction.
BACKGROUND
Following a myocardial infarction, patients are usually started on long term antiplatelet therapy with aspirin in a dose of 80-150 mg/day. However, there are no quick and easy methods to assess the efficacy of the antiplatelet activity of aspirin.


METHODS
We studied 60 consecutive patients (men, < 40 years of age) 8-10 weeks after they had had acute myocardial infarction. These patients were receiving 100 mg aspirin daily orally with or without b-blockers. We measured P-selectin expression and fibrinogen binding by flowcytometry at least 3 times over a period of 2 years in all the patients. We also studied 100 age- and sex-matched controls.


RESULTS
Of the 60 patients, 30 (50%) showed both increased P-selectin and fibrinogen binding by platelets, suggesting platelet activation. Fourteen other patients had increased fibrinogen binding but normal P-selectin expression. Sixteen patients and all the controls had normal results of both tests.


CONCLUSIONS
Our data show evidence of platelet activation in at least 50% of patients receiving 100 mg of aspirin daily. Flowcytometry for P-selectin expression and fibrinogen binding to platelets can be used to monitor antiplatelet therapy with aspirin following acute myocardial infarction.
Ghosh
K
K
Institute of Immunohaematology (ICMR), 13th floor, New Building, K.E.M. Hospital, Parel, Mumbai 400012, Maharashtra. kanjakshaghosh@hotmail.com
Khare
A
A
Shetty
S
S
Nair
S
S
Kulkarni
B
B
Mohanty
D
D
D000208:Acute Disease; D000328:Adult; D001241:Aspirin / Q000008:administration & dosage / Q000627:therapeutic use*; D050197:Atherosclerosis / Q000517:prevention & control; D016022:Case-Control Studies; D016861:Cyclooxygenase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D016903:Drug Monitoring; D005260:Female; D005340:Fibrinogen / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000503:physiopathology; D019007:P-Selectin / Q000187:drug effects; D015539:Platelet Activation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D011446:Prospective Studies; D012307:Risk Factors
D016861:Cyclooxygenase Inhibitors; D019007:P-Selectin; D010975:Platelet Aggregation Inhibitors; D005340:Fibrinogen; D001241:Aspirin