Variable response to antiplatelet therapy: what does it mean to clinicians?

Abstract

REVIEW ■ ABSTRACTEx vivo tests of platelet function show that platelet function and the response to antiplatelet therapy vary markedly from person to person. But just how clinically significant are ex vivo measurements of platelet function, and will changes we make based on such information translate into improved outcomes for patients? The authors summarize what is known and not known about the impact and clinical significance of variable response to antiplatelet therapy.

Aspirin nonresponse in patients with arterial causes of ischemic stroke: Considerations in detection and management

“…A decreased IPA in patients taking aspirin may also be caused by other means of platelet activation, including accelerated platelet turnover; erythrocyte-, isoprostane-, and catecholamine-mediated platelet activation; and increased platelet sensitivity to collagen [16,18]. For example, the transient decrease in aspirin response observed following coronary artery bypass grafting (CABG) [42] has been attributed to the increased platelet turnover that occurs following cardiopulmonary bypass (CPB).…”

“…It is well documented that platelet response to aspirin, as measured by ex vivo tests of platelet aggregation (Table 1) varies among individuals and ranges from hypo-to hypersensitivity [16][17][18]. A number of factors have been identified as possible contributors to the variability of platelet response to aspirin, only a few of which are modifiable ( Table 2).…”

“…Factors associated with variable patient response to aspirin[16,18] • Patient noncompliance • Underdosing • Non-Cox-1-mediated pathways of platelet activation • Accelerated platelet turnover • Increased platelet sensitivity to collagen…”

Epidemiology of Atherothrombotic Disease and the Effectiveness and Risks of Antiplatelet Therapy

“…This lack of consensus makes it difficult to draw meaningful conclusions concerning the relationship between ex vivo response variability and clinical outcomes. 52 Clinical outcomes are driven by multiple modifiable and nonmodifiable variables. Patient ethnicity is a nonmodifiable variable affecting clinical outcomes to some extent.…”