The well established importance of regular administration of antiplatelet drugs stands on firm grounds, as large meta-analyses have shown these therapies to significantly reduce the risk of death. Plavix® (clopidogrel) is widely used following coronary angioplasty, to reduce the risk of periprocedural thrombotic complications, for up to one year. As the current recommendations suggest clopidogrel use for no longer than one year, the drug is normally discontinued within that period. In the limited state of knowledge on antiplatelet drug withdrawal, an early sound of alarm has risen from early thromboembolic complications reported after the interruption of antiplatelet treatment used in prevention of ischemic vascular disease. Although little information is available, discontinuation of thienopyridines has been associated with increased thromboembolic complications, mainly acute stent thrombosis. These complications may signal a platelet sensitization effect to aggregating stimuli by antiplatelet drugs taken chronically.

The current study aims to evaluate the impact of clopidogrel discontinuation on platelet function, in order to shed light on underlying mechanisms leading to increased risk of acute thrombo-occlusive events.

Inclusion Criteria:

• Group 1: Patients suffering from stable CAD scheduled to discontinue clopidogrel therapy at least one month after stent implantation
• Group 2: Stable clopidogrel-naïve CAD patients
• Patients willing to participate in the study and to sign the informed consent form

Exclusion Criteria:

• Acute coronary syndrome or revascularization in the last 3 months prior to enrolment
• Concurrent ingestion of nonsteroidal anti-inflammatory drugs (NSAIDs, including COX-2 selective anti-inflammatory drugs), ticlopidine, dipyridamole, warfarin or acenocoumarol
• Major surgical procedure within 1 month before enrolment
• Platelet count outside the 100 000 to 450 000/μL range
• Hematocrit < 25% or haemoglobin < 100 g/L
• Patient undergoing dialysis for chronic renal failure

Patients with stable coronary artery disease