Comparison of laboratory detection methods of aspirin resistance in coronary artery disease patients

Abstract

Aspirin reduces the prevalence of nonfatal myocardial infarction, stroke, and death by 25.0% in high risk group of patients with cardiovascular disease. Previous studies have estimated that about 5.5-56.8% of the population are aspirin resistant. The mechanisms of aspirin resistance (AR) have not been fully understood. We compared the detection methods for AR using traditional platelet aggregometry and VerifyNow system. One hundred and seventy-two coronary artery disease patients who had taken aspirin only or combinations with aspirin and clopidogrel for over 7 days were included. Of the 55 patients with aspirin only, aggregometer detected six AR (10.9%) and VerifyNow identified 10 AR (18.2%) cases. Among 117 patients with combined therapy, none (0.0%) and 10 (8.5%) of AR were detected by aggregometer and VerifyNow, respectively. There were six (3.4%) patients of AR defined by both methods and they all received aspirin monotherapy. Although the correlation between the aggregometry and VerifyNow was low, with defined criteria both methods gave 91.9% agreement to find AR. VerifyNow showed a higher sensitivity to detect AR. Further studies are required to biologically define AR and to alter therapy based on platelet function tests.

Impaired Endogenous Thrombolysis in Acute Coronary Syndrome Patients Predicts Cardiovascular Death and Nonfatal Myocardial Infarction

“…Nonresponsiveness to antiplatelet drugs remains a major limitation in the prevention of future thrombotic episodes in patients who experience acute coronary syndrome (ACS). Previous studies estimated that 5.5% to 56.8% of the population are aspirin resistant (1), and the prevalence of clopidogrel nonresponsiveness was 21% (2). Although fewer published data are available for dual (aspirin and clopidogrel) nonresponsiveness, the incidence in a recent study involving 746 patients was only 6% (3).…”

Biochemical aspirin resistance in acute stroke patients and its association with clinical factors: a prospective pilot study

“…The prevalence of aspirin resistance varies from study to study, ranging from about 5% to 60% [9,15,28]. A meta-analysis of 52 full-text studies covering 8364 ischemic stroke/TIA patients on aspirin or clopidogrel revealed that the prevalence of high ontreatment of platelet reactivity to aspirin is 23% [8].…”

Aspirin Effects on Platelets Using Whole Blood Tested by Platelet Aggregometry: A Comparative Study for Test Validation in a Clinical Hemostasis Laboratory

“…A recent paper also discussed findings along these same lines; the researchers concluded that the prevalence of aspirin resistance depends on the type of test and agonist used. 13 In this study, aspirin effects on platelets using WB tested on conventional aggregometry (Chrono-Log aggregometer) could be determined by the absence of aggregation with AA, reduced ATP release with AA, and reduced aggregation with ADP and ristocetin. Although qualitative changes (ie, saw-tooth appearance) on ristocetin tracing did not yield significant findings, an association with platelet response to aspirin was observed.…”