Sustained increase in platelet aggregation after the cessation of clopidogrel

Area of Science:

• Cardiology
• Pharmacology
• Hematology

Background:

• Clopidogrel is a P2Y12 inhibitor commonly used after coronary stent implantation.
• The long-term effects of clopidogrel cessation on platelet function are not fully understood.
• Platelet hyperaggregability post-cessation may influence thrombotic risk.

Purpose of the Study:

• To investigate the impact of abrupt, one-year clopidogrel cessation on thrombotic events.
• To explore the causes of sustained increases in platelet aggregability after clopidogrel withdrawal.
• To assess the relationship between rebound platelet aggregation and response to other agonists.

Main Methods:

• Prospective, multicentre study of 200 patients with coronary stents on aspirin + clopidogrel.
• Platelet aggregation measured using ADP + PGE1 (ADPHS), thrombin receptor activating peptide (TRAP), and arachidonic acid (ASPI).
• Analysis of platelet aggregation at 10, 45, and 90 days post-clopidogrel cessation, stratified by ADPHS response.

Main Results:

• Abrupt cessation of one-year clopidogrel treatment was not associated with thrombotic events.
• Platelet aggregation stimulated by ADP + PGE1 significantly increased 10-90 days after clopidogrel cessation.
• Patients with early pronounced rebound phenomena showed long-term increased platelet aggregation to TRAP and ASPI.

Conclusions:

• One-year clopidogrel cessation appears safe regarding thrombotic events in this cohort.
• Early rebound hyperaggregability to ADP predicts sustained increased platelet reactivity to other agonists.
• Complex interactions between various agonists influence platelet function following clopidogrel withdrawal.