Decrease in microvesicle-associated tissue factor activity in morbidly obese patients after bariatric surgery

Tissue factor (TF) is the main in vivo initiator of the blood coagulation cascade. Active circulating TF was detected on small, negatively charged membrane vesicles, the so-called microvesicles (MVs), which are released upon cell activation and apoptosis from a variety of cells. Increased coagulation activation was found in morbidly obese patients, and elevated levels of TF-bearing MVs may contribute to the prothrombotic state in these patients.

To determine MV-associated TF activity levels in morbidly obese patients before and after weight loss due to bariatric surgery.

MV-TF activity was measured with a factor Xa generation assay in morbidly obese patients before and 2 years after bariatric surgery. In addition, clinical parameters were determined.

Seventy-four morbidly obese patients (mean age: 42 (±11) years; 61 females) were included in this study. After bariatric surgery, the body mass index decreased from (median, 25-75th percentile) 45.5 (42.3-50.2) to 30.5 (28.0-34.4 kg m(-2); P<0.001), and a significant improvement in metabolic parameters was observed. Preoperative MV-TF activity correlated with C-reactive protein levels (r=0.3; P=0.02). Postoperatively, the mean MV-TF activity decreased significantly from 0.20 pg ml(-1) (0.18-0.47) to 0.02 (0.00-0.28; P<0.01).

We could demonstrate a significant decrease in MV-TF activity after weight loss in morbidly obese patients. Decreased MV-TF activity might contribute to an improved coagulation profile in these patients after weight loss.