Effect of antifibrinolytic therapy with tranexamic acid on abdominal aortic aneurysm shrinkage after endovascular repair

Objective: The long-term outcomes of endovascular abdominal aortic aneurysm repair (EVAR) remain to be determined, but patients with aneurysm shrinkage after EVAR appear to have a good prognosis. We previously observed that antiplatelet therapy is a risk factor for lack of aneurysm shrinkage, a finding suggesting that coagulation and fibrinolysis play roles in shrinkage. We therefore studied the effect of antifibrinolytic therapy with tranexamic acid (TXA) on aneurysm shrinkage after EVAR. Methods: From May 2007 to May 2012, EVAR was performed in 187 patients, 165 of whom had an enhanced computed tomographic evaluation 6 months after their procedure. Six of the 165 patients were excluded from the study because they had a type Ia endoleak or coil embolization to treat a type II endoleak <= 6 months after EVAR. Of the remaining 159 patients, 110 underwent EVAR before we started to use TXA in our centers. TXA therapy (1500 mg/d for 6 months) began in January 2011, and 48 patients completed the treatment regimen. Patients not treated with TXA were compared with those given TXA. Analyses to identify risk factors for lack of aneurysm shrinkage were performed. Results: No patient had a thromboembolic event. There were no significant differences between the no-TXA and TXA groups in demographics, aneurysm characteristics, prosthesis implanted, type II endoleak occurrence during EVAR or 1 or 6 months afterward, or aneurysm shrinkage at 1 month. However, at 6 months after EVAR, the TXA group had significantly greater aneurysm shrinkage (P = .035) and a significantly higher percentage of patients with >4 mm in shrinkage (P = .010). Multiple regression analysis showed aneurysm diameter, type II endoleak 6 months after EVAR, and TXA treatment were independently associated with aneurysm shrinkage or lack of shrinkage. Conclusions: Antifibrinolytic therapy with TXA was associated with aneurysm shrinkage after EVAR. Studies to identify the dosage of TXA that is optimally safe and effective in this application, as well as investigations of the best timing and route (parenteral vs oral) for TXA administration, are warranted.