Predicting Microvascular Thrombotic Complications with Thromboelastography and Platelet Mapping: A Preliminary Investigation

PURPOSE: Recent technical refinements in free-tissue transfer (FTT) have significantly decreased the incidence of complications, yet thrombosis persists as the leading cause of flap failure. Thromboelastography (TEG) analyzes the viscoelastic properties of blood and the addition of platelet mapping provides a comprehensive analysis of a patient's coagulation potential and postoperative aspirin efficacy. Because aspirin is the most ubiquitous choice for postoperative anticoagulation, evaluating for potential factor contribution to persistent hypercoagulability is paramount. This prospective pilot study utilizes TEG to evaluate perioperative anticoagulation efficacy in patients undergoing FTT as well as predictive parameters for patients with thrombotic complications. METHODS: 27 consecutive patients with FTT underwent TEG analysis pre- and postoperatively at standardized time points. All patients received postoperative subcutaneous heparin and oral aspirin, and patients with thrombosis additionally received a heparin bolus followed by non-nomogram IV heparin. Two-sample t-tests were conducted for all parameters. Primary assessment included (1) adequate antiplatelet efficacy with aspirin postoperatively and (2) inadequately treated factor contribution in thrombotic versus nonthrombotic patients to assess significance in TEG's predictive value. RESULTS: Twenty-seven patients underwent FTT (19 DIEP/ms-TRAM, 3 RFFF, 3 FFF, 1 ALT, 1 LD) from February 2020 to October 2020. Mean age was 56.1 years, mean BMI was 25.1 kg per m2, 19 patients were women, 18 patients identified as non-Hispanic White, and 20 patients had private health insurance. Four patients developed intraoperative anastomotic thrombosis with one patient requiring an additional operative return on postoperative day 2. Compared with control cohort of patients who did not develop thrombosis, the thrombotic patients had statistically significant preoperative TEG values: (1) decreased SP time (P < 0.04), (2) decreased R time (P < 0.04), (3) decreased K value (P < 0.05), and (4) decreased LY30 (P < 0.001). Please refer to Table 1 for comparison in detail. In the patient who required additional operative intervention, the postoperative TEG revealed platelet inhibition of 79.1%, revealing inadequate aspirin effects despite prophylactic dosing. CONCLUSIONS: TEG represents a breakthrough innovation that could provide treatment-specific, predictive information regarding the hypercoagulability of patients receiving FTT. Our series demonstrates that patients with thrombotic complications exhibited derangements in their blood's coagulation detectable by TEG. Preoperative presence of factor or platelet hyperactivity accurately predicted thrombotic complications. Although these patients all received post-thrombotic heparin, prospective analysis reliably predicted the need for anticoagulation and antiplatelet therapy as well. Further, the postoperative TEG analysis can evaluate efficacy of antiplatelet therapy. Overall, this study underscores the value of TEG analysis in providing a patient-specific approach to pharmacologic anticoagulation to reduce thrombotic complications.