Abstract 1534: Platelet Reactivity Decreases After Exercise Training and Weight Loss in Overweight Patients With Coronary Artery Disease
Objective: Although exercise may activate platelets and increase platelet reactivity acutely, long-term benefits of regular exercise and weight loss on obesity and inflammation may counteract acute effects. We hypothesized that platelet reactivity would decrease with cardiac rehabilitation (CR) exercise training and weight loss.
Methods: Overweight subjects with coronary artery disease (CAD, n<44) not taking clopidogrel were randomly assigned to standard CR or high-caloric expenditure exercise (Hi-Cal CR) with both groups receiving behavioral weight loss. Platelet reactivity was determined by platelet surface expression of P-selectin in response to 1 μM ADP with the use of flow cytometry a minimum of 36 hours after last exercise. High-sensitivity C-reactive protein (CRP) was quantified by ELISA. Body composition measures included weight, body mass index, waist circumference and fat mass assessed by dual x-ray absorptiometry. Physical activity energy expenditure (PAEE) was measured with the doubly-labeled water technique. Results were compared with paired Student’s t-test, analysis of variance and multiple regression analysis.
Results: The Hi-Cal group experienced greater weight loss than the standard CR group (8.3±5.0 vs. 4.6±4.7 kg, respectively, p<0.02). Both groups increased aerobic fitness similarly. Platelet reactivity decreased after 4 months in the combined group (from 33±17% to 29±17% of platelets activated, p<0.01), a reduction that was greater in the Hi-Cal group (−6±12% vs −3±13%, p<0.01). Women (n=10) exhibited a substantially greater decrease in platelet reactivity (−12±9% vs. −2±13% for men, p for gender adjusted for group = 0.03). Change in platelet reactivity was independently and positively associated with change in PAEE (r=0.36, p=0.02) and CRP (r=0.40, p<0.01). Body composition changes were not associated with changes in platelet reactivity.
Conclusion: Platelet reactivity decreased in individuals with CAD undergoing CR and weight loss. Despite a positive correlation between PAEE and platelet reactivity, we observed an overall reduction in platelet reactivity that correlated with a reduction in CRP. Platelet reactivity decreased to a greater extent in those undergoing Hi-Cal CR and in women.