Effect of Clopidogrel Loading and Risk of PCI
Effect of Clopidogrel Loading and Risk of PCI
This study is a prospective, single-center evaluation of the impact of the variability in
 platelet response after loading with clopidogrel on the peri-interventional risk of patients
 undergoing PCI.
Background: Platelet responses after loading with clopidogrel are highly variable. The impact
 of this variability on the peri-interventional risk of patients undergoing PCI has not been
 investigated prospectively.

 Objectives: Our prospective study test the hypothesis that the 30-day clinical outcome of
 elective percutaneous catheter intervention (PCI) differs between strata defined by quartiles
 of platelet aggregation after loading with 600mg of clopidogrel. Further on we will
 investigate impact of the variability in platelet response on long-term outcome after PCI.

 Methods: Our study will include consecutive patients undergoing elective coronary stent
 placement. Before PCI, patients receive a loading dose of 600mg of clopidogrel followed by
 75mg daily. Primary end point is the 30-day composite of death, myocardial infarction and
 target lesion revascularization (MACE). Platelet aggregation was assessed immediately before
 PCI by optical aggregometry (5µmol/L ADP).

 Sample size calculation was based on ISAR-REACT which comprised a cohort with similar
 selection criteria and treatment strategy. Thus, we assume an incidence of the primary end
 point of 4.2%. We design our study to test the hypothesis that the incidence of the primary
 end point differed by quartiles of ADP-induced platelet aggregation. We intend to have a
 power of 0.80 to detect an effect size of 0.015 (for example 3-fold risk in 4th quartile)
 with a 2-sided P-value less than 0.05. With these assumptions we obtain a sample size of at
 least 748 and aime for a cohort of 800.
Inclusion Criteria:

 -  Patients undergoing elective coronary stenting

 -  Pretreatment with a bolus dose of 600mg of clopidogrel prior to coronary stent
 implantation

 -  Pretreatment with aspirin ≥ 100 mg per day for at least 7 days

 -  Age > 18 years

 -  Written consent

 Exclusion Criteria:

 -  Troponin T on admission > 0.03 ng/mL

 -  Myocardial infarction or fibrinolytic therapy within the previous 14 days

 -  Cardiogenic shock

 -  Contraindication for aspirin or clopidogrel

 -  Oral anticoagulation

 -  Pretreatment with heparin or a thienopyridine within the previous 14 days

 -  Use of a GP IIb/IIIa-receptor antagonist during PCI

 -  Platelet count < 100.000/µl

 -  Severe disorders of the coagulation system

 -  Severe impairment of liver or kidney function

 -  Cancer