Impact of body mass index on platelet aggregation after administration of a high loading dose of 600 mg of clopidogrel before percutaneous coronary intervention.

This study assessed the effect of body mass index (BMI) on platelet aggregation after administration of a high loading dose of clopidogrel 600 mg. Blood samples of 402 patients before percutaneous coronary intervention were collected >or=2 hours after administration of clopidogrel 600 mg. Platelet aggregation was measured in response to adenosine diphosphate (ADP; 5 and 20 microM). Patients were categorized as normal weight (BMI <25 kg/m(2)) or overweight (BMI >or=25 kg/m(2)). ADP-induced platelet aggregation was significantly higher in overweight patients than in normal-weight patients (46.0 +/- 21.8% vs 38.2 +/- 19.3% for ADP 5 microM, p = 0.0007; 55.1 +/- 22.7% vs 45.2 +/- 21.7% for ADP 20 microM, p <0.0001). Multivariate analyses demonstrated high BMI as the only independent predictor for increased ADP-induced platelet aggregation (p <or=0.005). In conclusion, administration of a single high loading dose of clopidogrel 600 mg does not inhibit platelet aggregation in overweight patients to the same extent as in normal-weight patients.