[Intra-individual variability of the platelet anti-aggregation effect of aspirin in coronary patients].
Several studies have reported a biochemical resistance to aspirin in 5 to 10% of coronary patients. However, the stability of the platelet anti-aggregation effect with aspirin over time remains poorly understood.


OBJECTIVE
To study the intra-individual variability at 6 months of the anti-platelet action of aspirin in coronary patients.


METHODS
Prospective study including 40 consecutive patients with acute coronary syndrome and taking regular aspirin (250 mg a day). The biochemical impact of aspirin was determined by measuring the time to occlusion (TO) on a collagen/epinephrine cartridge with PFA-100. The determination of the TO was performed 2 months (TO1) and then 8 months (TO2) after starting aspirin. In our population, a resistance to aspirin was defined as a TO < or =125 sec.


RESULTS
The median value for TO was generally stable over the two periods, at 158 sec for TO1 and 179 sec for TO2 (p = 0.29). Among the 9 initially resistant patients (22.5%), 4 became sensitive to aspirin without changing the dosage, while only one of the 31 initially sensitive patients became biochemically resistant.


CONCLUSIONS
the existence of a medium term intra-individual variability in the antiplatelet response to aspirin in coronary patients underlines the importance of biochemical surveillance in these high vascular risk patients.
Addad
F
F
Service de cardiologie, CHU Fattouma Bourguiba, Tunisie. faouzi.addad@rns.tn
Hassine
M
M
Ben Farhat
M
M
Abderrazak
F
F
Chakroun
T
T
Gamra
H
H
Hamdi
S
S
Betbout
F
F
Samama
M
M
Elalamy
I
I
D000208:Acute Disease; D000328:Adult; D000368:Aged; D001241:Aspirin / Q000627:therapeutic use*; D003327:Coronary Disease / Q000188:drug therapy*; D004351:Drug Resistance; D006801:Humans; D008875:Middle Aged; D015588:Observer Variation; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D015203:Reproducibility of Results
D010975:Platelet Aggregation Inhibitors; D001241:Aspirin