The relationship between aspirin resistance and endothelial dysfunction in patients with stable coronary artery disease

OBJECTIVES
Endothelial dysfunction may enhance platelet aggregation despite regular aspirin therapy. We investigated the relationship between aspirin-resistant platelet aggregation and endothelial dysfunction in patients with stable coronary artery disease.

STUDY DESIGN
The study included 98 patients (60 males, 38 females; mean age 62±8 years) receiving medical treatment for stable coronary artery disease. Platelet function assays were performed with the Platelet Function Analyzer (PFA)-100 with collagen and epinephrine (Col/Epi) and collagen and adenosine diphosphate cartridges. Aspirin resistance was defined as a closure time of less than 186 seconds with Col/Epi cartridges despite regular aspirin therapy. Endothelial function was assessed via measurement of flow-mediated dilatation by brachial artery ultrasonography.

RESULTS
Twenty patients (20.4%) were found to be aspirin-resistant by the PFA-100. There were no significant differences between patients with and without aspirin resistance with respect to the mean aspirin dose administered and other medications. The mean basal diameter of the brachial artery was 4.11 mm and the mean flow-mediated dilatation (percentage change from basal diameter) was 4.7% in patients with aspirin resistance. The corresponding figures were 4.14 mm and 5.3% in the absence of aspirin resistance (p>0.05).

CONCLUSION
In our study, endothelial dysfunction was found in all the patients with stable coronary artery disease, without any association of its presence and severity with aspirin resistance.