The Association of Antiplatelet Aggregation Effect of Aspirin and Platelet Count. Possible Dosage Implications

Hernán Cohen Arazi, Mariana Carnevalini, Estela Falconi, Rodrigo Ovejero, Mariano Giorgi, Christian Caroli, Carlos Nojek, Juan J. Badimon

Abstract


Background

Thirty percent of patients do not achieve an adequate antiplatelet

effect despite therapy with aspirin (ASA) 100 mg/d

after coronary artery bypass-graft surgery (CABGS), probably

due to reduced inhibitory effect of ASA, increased platelet

activation and increased platelet turnover secondary to the

surgical procedure.

Objectives

To evaluate the relation between platelet count and lower

antiplatelet effect and to determine if antiaggregation improves

by dividing the dose of ASA.

Material and Methods

A total of 50 patients undergoing CABGS (with an average

of 2.95 grafts per surgery) were randomly assigned to three

groups depending on the dose of ASA indicated: G100 (100

mg/d, n=18 patients), G300 (300 mg/d, n=14) and G100×3

(100 mg TID, n=18). All the patients received 100 mg/d before

surgery. Platelet reactivity was assessed by whole blood

impedance using arachidonic acid before surgery (T0), 24 h

(T1), 72 h (T2), 7 days (T3), and one month post-CABG (T4).

Results

Before surgery, all patients had optimal values of antiaggregation

(0 W). During the postoperative period, antiaggregation

values were better in patients from G100×3 (p <0.05). No

patients in G100×3 had values ≥ W, which correspond to

those of healthy subjects who do not receive ASA. This value 

was observed in 5 patients (28%) from G100 and 4 patients

(29%) from G300. The association between antiaggregation

and platelet turnover was statistically significant (R2=0.57;

p=0.001). A daily turnover >20% was related with values of

platelet aggregation ≥6 W; OR=2.1 (CI 1.8-4.21; p=0.0028).

Conclusions

In patients undergoing CABGS, the lowest antiplatelet effect

of ASA was associated with the highest platelet turnover. A

better antiaggregation might be achieved by dividing therapy

in low dose of ASA.


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Revista argentina de cardiología. ISSN en línea 1850-3748. Argentine journal of cardiology (English ed. Online ISSN 2314-2286) Sociedad Argentina de Cardiología. Azcuénaga 980 (C1115AAD),Ciudad Autónoma de Buenos Aires, República Argentina. Tel. (54 11) 4961-6027/8/9 Fax: 4961-6020 www.sac.org.ar revista@sac.org.ar