Incidence and Evolution of Mural Thrombus in Abdominal Aortic Endografts

Background: The aims of this study were to analyze the predictive factors for intragraft mural thrombus formation and evolution during follow-up after endovascular treatment of abdominal aortic aneurysms and to evaluate its relationship with the subsequent appearance of complications. Methods: A retrospective study was performed by selecting those patients who underwent endovascular repair of an abdominal aortoiliac aneurysm between June 1998 and September 2004, with a minimum follow-up of 24 months. Preoperative clinical data, anatomical characteristics of the aneurysm, and endograft type were analyzed. In addition, clinical evaluation and abdominal computed tomography angiography (CT scans) performed at 1, 6, 12, and 24 months after the surgery were reviewed. Results: Eighty-nine patients were submitted for endovascular aneurysm repair in this period, and 75 completed the 24-month follow-up. Eighteen patients developed intragraft mural thrombus (24% incidence), 13 (72.2%) appearing at 1 month of follow-up, and up to 16 (88.9%) appearing during the first 6 months. Logistic regression analysis showed that the lumen percentage of mural thrombus in the native aorta and the use of aortouniiliac endografts were independent predictors of intragraft mural thrombus formation (odds ratio, 1.065; 95% confidence interval, 1.022-1.110, and odds ratio, 8.014; 95% confidence interval, 1.598-40.181, respectively). No spontaneous regression of the thrombus was observed. The area of intragraft mural thrombus had increased at 12 and 18-24 months after their diagnosis (Wilcoxon signed rank test, p = 0.028 and 0.028, respectively). The presence of intragraft mural thrombus was associated with a greater tendency to endograft body or branch occlusion (5 of 18 cases with intragraft mural thrombus (27.8%) versus 1 of 57 cases without it (1.8%), (p = 0.003). Conclusion: Intragraft formation of mural thrombus is a common finding during the follow-up of abdominal aortic endografts, particularly in aneurysms with large mural thrombus of the native aorta, and is associated with the use of aortouniiliac endografts. The area occupied by the mural thrombus was shown to gradually increase during follow-up and was associated with a greater tendency for endograft occlusion. © 2009 Annals of Vascular Surgery Inc.