Evaluation of aspirin resistance and the presence of unstable carotid plaque in patients undergoing carotid endarterectomy.

BACKGROUND

Antiplatelet therapy using low dose acetylsalicylic acid (ASA) is routinely recommended in patients undergoing surgical or endovascular treatment of carotid artery disease. Despite this treatment, a significant proportion of postoperative complications may result from inadequate response to antiplatelet therapy which may contribute to the development of unstable plaques.

AIM

Assessment of correlation between ASA resistance and the presence of unstable carotid plaque in patients after carotid endarterectomy.

METHODS

We studied 66 patients (27 women and 39 men) aged 41-80 years who were operated for carotid stenosis. All patients received ASA (75 mg once daily) in the pre- and perioperative period. Measurements of platelet reactivity were performed using the PFA-100 platelet analyser at the second day after the operation. Plaque stability was evaluated using a computer analysis system based on the greyscale median method. The patients were divided into two groups, showing good response to ASA or ASA-resistant.

RESULTS

ASA resistance was identified in 19 (32%) patients. In multivariate logistic regression analysis, unstable plaque showed a borderline correlation with ASA resistance (p = 0.051).

CONCLUSIONS

1. Prevalence of increased platelet reactivity despite ASA treatment (ASA resistance) in patients treated surgically for carotid artery disease is high, suggesting a possibility of ineffective antiplatelet therapy. 2. A modest correlation between abnormal platelet response during treatment with ASA and the presence of unstable plaques suggests that these two phenomena may coexist but we were unable to show a clear association between them.