[Beneficial effect of a loading dose of 600 mg of clopidogrel on platelet parameters in patients admitted for acute coronary syndrome].
BACKGROUND
Despite the beneficial effect of an aspirin-clopidogrel combination in acute coronary syndrome, the incidence of ischaemic recurrences remains significant and very probably implicates a variability in the response to anti-platelet agents.


OBJECTIVE
We sought to demonstrate the evidence for a beneficial effect, in terms of anti-platelet effect, of a higher loading dose of 600 mg of clopidogrel compared to the usual 300 mg in patients admitted to our centre with acute coronary syndrome.


METHODS
Platelet reactivity was evaluated with the ADP 10_mol test and the degree of platelet activation by the expression of P-selectin. 178 consecutive patients admitted for acute coronary syndrome received 250 mg of intravenous aspirin together with either a loading dose of 300 mg of clopidogrel (n = 104) or 600 mg (n = 74) administered 12 to 24 hours prior to coronary angiography.


RESULTS
The patients who received 600 mg of clopidogrel had an average aggregation intensity to ADP and a rate of platelet high reactivity post treatment that was significantly lower [48+20 vs 58+18, p = 0.0011 and 11 patients (15%) vs 26 patients (25%), p = 0.0003 respectively]. The degree of platelet activation evaluated with P-selectin was significantly lower in patients receiving 600mg [0.33 + 0.17 vs 0.50+0.29, p < 0.001].


CONCLUSIONS
Our study provides evidence for a beneficial effect of a loading dose of 600mg of clopidogrel compared to the usual 300 mg in terms of platelet reactivity and platelet activation post treatment.
Cuisset
T
T
Département de cardiologie interventionnelle CHU de la Timone. thomascuisset@voila.fr
Frère
C
C
Quilici
J
J
Morange
P E
PE
Saidi
L Nait
LN
Carvajal
J
J
Lambert
M
M
Mouret
J P
JP
Alessi
M C
MC
Bonnet
J L
JL
D000208:Acute Disease; D000789:Angina, Unstable / Q000097:blood / Q000188:drug therapy*; D000077144:Clopidogrel; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000188:drug therapy*; D015539:Platelet Activation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D013577:Syndrome; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*
D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine