Background: This study assessed hemostatic function in cancer patients at high risk for venous thromboembolism. Methods: Thirty-eight female patients (age, 53 ± 9 years) undergoing immediate postmastectomy reconstruction were prospectively studied with informed consent. Blood was sampled preoperatively, on postoperative day 1, and at 1 week follow-up. Rotational thromboelastography clotting time, α-angle (clot kinetics), clot formation time, and maximum clot firmness were studied with three different activating agents: intrinsically activated test using ellagic acid, extrinsically activated test with tissue factor, and fibrin-based extrinsically activated test with tissue factor and the platelet inhibitor cytochalasin D. Thromboprophylaxis was unfractionated heparin plus sequential compression devices if not contraindicated. Hypercoagulability was defined by one or more parameters outside the reference range. Results: Preoperatively, 29 percent of patients were hypercoagulable, increasing to 67 percent by week 1 (p = 0.017). Clotting time, clot formation time, and α-angle remained relatively constant over time, but maximum clot formation increased in intrinsically activated test using ellagic acid, extrinsically activated test with tissue factor, and fibrin-based extrinsically activated test with tissue factor and the platelet inhibitor cytochalasin D (all p < 0.05). Body mass index was 28 ± 5 kg/m2, 23 percent received preoperative chemotherapy, and 15 percent had a history of tobacco use, but there was no association between these risk factors and hypercoagulability. Conclusions: Despite perioperative thromboprophylaxis, two-thirds of patients undergoing combined tumor resection and reconstructive surgery for breast cancer were hypercoagulable 1 week after surgery. Hypercoagulability was associated with increased clot strength mediated by changes in platelet and fibrin function.
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