High On-Treatment Platelet Reactivity to Both Aspirin and Clopidogrel Is Associated With The Highest Risk of Adverse Events Following Percutaneous Coronary Intervention

Jul 08, 2011
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Authors:
Breet NJ, van Werkum JW, Bouman HJ, et al.
Citation:
Heart 2011;97:983-990.
Summary By:
Debabrata Mukherjee, MD, FACC

Study Questions:

What is the incidence of dual high on-treatment platelet reactivity (DAPR) and its impact on clinical outcome?

Methods:

On-treatment platelet reactivity was measured in parallel by ADP- and arachidonic acid-induced light transmittance aggregometry (LTA) (n = 921) and the point-of-care VerifyNow system (P2Y12 and aspirin) (n = 422) in patients on dual antiplatelet therapy undergoing elective stent implantation. High on-clopidogrel platelet reactivity (HCPR) and high on-aspirin platelet reactivity (HAPR) were established by receiver-operator characteristic curve analysis. The primary endpoint was a composite of all-cause death, nonfatal acute myocardial infarction, stent thrombosis, and ischemic stroke at 1-year follow-up.

Results:

The incidence of DAPR varied between 14.7% and 26.9% depending on the platelet function test used. DAPR, assessed by LTA and the VerifyNow system, was highly associated with an adverse clinical outcome. At 1-year follow-up, the primary endpoint occurred more frequently in patients with isolated HCPR (11.7%), isolated HAPR (9.6%), or DAPR (10.7%) compared with patients without high on-treatment platelet reactivity (4.2%, all p < 0.01) when platelet function was evaluated with LTA. Using the VerifyNow system, patients exhibiting DAPR had the highest risk for the primary endpoint (17.7% vs. 4.1% in patients without high on-treatment platelet reactivity, p = 0.001).

Conclusions:

The authors concluded that in patients undergoing elective percutaneous coronary intervention (PCI), DAPR to aspirin and clopidogrel is present in one in five patients and is associated with a high risk for atherothrombotic events.

Perspective:

The study reports that DAPR occurs with varying prevalence and may occur in one in five patients undergoing elective PCI. Furthermore, DAPR is associated with the occurrence of atherothrombotic events and appears to be a better predictor of an adverse outcome than isolated HCPR or HAPR. The concept of tailored platelet therapy based on platelet function testing, while promising, needs prospective randomized evaluation.

Keywords: Incidence, Myocardial Infarction, Stroke, Follow-Up Studies, Platelet Aggregation Inhibitors, Blood Platelets, Platelet Activation, Percutaneous Coronary Intervention


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