Computed tomography angiography-confirmed aortic in-stents floating thrombus after endovascular stenting: a retrospective study

Abstract

Background: Aortic in-stents floating thrombus (ASFT) is a rare complication. The evolution of ASFT on computed tomography angiography (CTA) imaging and the treatment options remain under investigations. The aim of this study was to analyze the imaging manifestations of ASFT on CTA, and to explore safe and effective treatment options.

Methods: A retrospective, longitudinal study design was used. Clinical and imaging data were collected from patients with ASFT between January 2015 to December 2022 at the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. The imaging features of ASFT, including location, morphology, size, concomitant and dynamic changes during follow-up, were analyzed and classified into two types based on imaging manifestation. Type 1 showed a striated, irregular, or sheet-like appearance. Type 2 was a free-floating middle section in the cavity with attachment point to the thickened inner wall. The treatment protocol was also investigated. The Mann-Whitney U test was utilized for variable comparison.

Results: A total of 1,626 cases were screened, out of which 10 cases were enrolled, resulting in an incidence rate of ASFT of 0.62% (10/1,626). The pre-surgery levels of fibrinogen (FIB), prothrombin time (PT), and D-dimer showed a higher trend, while only the D-dimer level increased significantly during the postoperative period (P<0.001). During the follow-up, CTA examination detected 21 ASFTs, including 18 ASFTs of type 1 and three ASFTs as type 2. One patient experienced spleen infarction when ASFT developed. During the follow-up period, thrombus disappeared in six patients, while the lesions remained stable in four patients. Renal infarction occurred in one case. No new-onset ASFTs or patient deaths were reported.

Conclusions: ASFT is an extremely rare disease. The concomitant disorders and postoperative hemodynamic changes could be the cause. CTA examination presented as a safe and preferred imaging modality for evaluating the evolution and prognosis of ASFT. Conservative treatment may be a useful and effective option.

Keywords: Aortic in-stents floating thrombus (ASFT); aortic stent; computed tomography angiography (CTA); embolization.

Figure 1

Flow chart of the study. CTA, computed tomography angiography; ASFT, aortic in-stents floating thrombus.

Figure 2

A 57-year-old male patient with AAA. CTA-MPR images revealed one stripe filling defect in the descending aorta post-treatment. Extensive atherosclerotic plaques were observed in the descending aorta before the surgery (A,B, red arrows). One and a half months after the surgery, an ASFT was found attached to the focal thickened wall, which was closely associated with the preoperative atherosclerotic plaque. (C,D, red arrows). Subsequent CTA examination performed 7 months later showed that the lesion had disappeared (E,F, red arrows). AAA, abdominal aortic aneurysm; ASFT, aortic in-stents floating thrombus; MPR, multi-planar reconstruction; CTA, computed tomography angiography.

Figure 3

A 60-year-old male patient with AAD. At 1-month follow-up after the treatment, CTA-MPR images identified two stripe filling defects. The atherosclerotic plaque and mural thrombus were revealed before operation (A, red arrow, red triangle). During the follow-up period, one lesion bifurcated distally with a small branch (B,C, red arrows). One flaky filling defect was attached to the focal thickened wall (C, red triangle). At 2-month follow-up after the operation, the infarction of the inferior part of the right kidney was observed (D, red triangle), as well as the disappearance of both lesions (E,F, red arrows, red triangle). AAD, abdominal aortic dissection; CTA, computed tomography angiography; MPR, multi-planar reconstruction.

Figure 4

A 67-year-old male patient with AAA. Axial and sagittal CTA images confirmed a pedunculate mass (0.15 cm × 0.09 cm × 0.11 cm) in the stent. Diagnose of AAA was confirmed before the surgery (A, red star mark). At the 3-month follow-up, a pedunculated mass (B, red arrows) with three attachment points between the free-floating distal segment and the mural thrombus was observed (C, red arrows). The 9-month CTA examination after the procedure confirmed the disappearance of the lesion (D, red arrow). CTA, computed tomography angiography; AAA, abdominal aortic aneurysm.

Video S1

The floating process of the aortic in-stents floating thrombus through the cardiac cycle on cine-computed tomography.