Obesity and antiplatelet effects of acetylsalicylic acid and clopidogrel in patients with stable angina pectoris after percutaneous coronary intervention.

Introduction: Obesity is a cluster of medical conditions affecting several pathophysiological processes, including platelet (PLT) function.
Objectives: We evaluated the association between obesity and PLT response to dual antiplatelet therapy over 1 month in patients with stable angina pectoris after percutaneous coronary intervention (PCI). 
Patients and Methods: Patients with stable angina pectoris (n = 130) and prior therapy with acetylsalicylic acid (ASA, 75 mg/d) after PCI were enrolled into the study and divided based on a body mass index (BMI): BMI <25 kg/m² (group A); BMI = 25-29.9 kg/m² (group B); and BMI ≥30 kg/m² (group C). PLT function was assessed by impedance aggregometry 24 hours after PCI and a loading dose (LD) of clopidogrel (CLO, 600 mg) and after 30 days of a maintenance dose (MD) of CLO and ASA of 75 mg/d. The delta values were calculated as the difference between the tests performed 30 days and 24 hours after PCI.
Results: The PLT function changed significantly over a 30-day follow-up. The initial PLT reactivity to adenosine diphosphate (ADP1) was lower in group A and was the highest in group C (P <0.05). The PLT reactivity to collagen (COL1) and arachidonic acid was lower in group A (P <0.05) with no differences between groups B and C. There were no differences among the subgroups in PLT reactivity assessed after 30 days. A multivariate regression analysis showed that BMI (P = 0.03), creatinine serum concentration (P <0.01), male sex (P <0.01), and active smoking (P <0.001) are the independent predictors of ΔADP. CONCLUSIONS Obesity is associated with a lower response to CLO LD but PLT function after 30 days of CLO MD is similar in patients with obesity and normal-weight.