Aspirin responsiveness changes in obese patients following bariatric surgery

Bariatric surgery has emerged as a promising treatment option for weight loss and to counter the metabolic consequences of obesity. Obesity has been linked to a hyperaggregable state, as well as a blunted response to aspirin. This pilot study assessed the hypothesis that bariatric surgery would lead to an improvement in aspirin-induced platelet inhibition and a reduction in platelet aggregability. Methods Fifteen patients scheduled to undergo bariatric surgery were administered two 7-day courses of aspirin 81 mg: the first course administered before surgery and the second was 3 months following surgery. Platelet aggregation was measured before and after each aspirin course using VerifyNow-Aspirin. The primary endpoint was the change in on-treatment aspirin reactive units (ARU) pre- and post-surgery. Data from bariatric surgery study patients were compared to data of normal weighted subjects gathered in a previous study. Results Roux-en-Y gastric bypass was performed in 80% and 20% underwent sleeve gastrectomy. The mean starting body mass index (BMI) was 46.9 kg/m2. Patients lost on average 24.5 kg, resulting in a post-surgical BMI of 38.5 kg/m2. Post-bariatric surgery, off-treatment ARU was significantly reduced from pre-surgery levels (602 ± 59 vs. 531 ± 78; p = 0.035). On-aspirin platelet reactivity was also significantly reduced following surgery (469 ± 60 vs. 432 ± 143, p=0.03). There was a significant correlation between the extent of weight loss and the degree of improvement in on-aspirin platelet reactivity (r2= 0.49, p = 0.024). Pre-surgery on-aspirin platelet reactivity was significantly higher in obese patients compared to normal weighted subjects (469 ± 60 vs. 419 ± 52; p = 0.016) and reduced to the baseline after the surgery (432 ± 63 vs. 419 ± 52; p = 0.54). Conclusion Aspirin- induced platelet inhibition may be more potent following bariatric surgery. The mechanisms behind this improvement require further investigation. This article is protected by copyright. All rights reserved.