Primary aortic mural thrombus (PAMT), defined as the presence of parietal aortic thrombosis in a normal structural aorta with minimal or no atherosclerosis, is quite rare. It can be an incidental finding with no symptoms; however, in some cases can have devastating consequences with embolization through multiple arterial beds. No recommendations exist to dictate the best management. Anticoagulation alone proved to be effective, although some patients' recurrence of embolic events suggests that they could benefit from surgical or endovascular treatment. This study aims to describe our experience in treating this rare disease.

We review our experience managing PAMT through a retrospective analysis of data from patients treated at our institution between January 2015 and December 2021. We collected information regarding demographics, cardiovascular and prothrombotic risk factors, clinical presentation, type of treatment, and outcome. We also review computed tomography imaging findings for thrombus and embolization location.

We identified 14 patients with PAMT. The patient's mean age was 54.4 years, ranging from 36 to 69 years. The male/female ratio was 1:1.8 (5 males; 9 females). Twelve patients (86%) had thoracic PAMT (ascending, n=1; arch, n=5; descending, n=6), and two had thrombus located in the abdominal aorta (14%). Twelve patients (86%) had pedunculated thrombi, with a sessile morphology in the others. Every patient had at least one cardiovascular risk factor. Overweight (BMI>25) was the most common, present in all patients with a median BMI of 30,5 Kg/m2 (range 26 - 37Kg/m2). Ten patients (70%) had dyslipidemia, half (50%) had a present or previous history of tobacco abuse, and eight (57%) had hypertension. The most common form of presentation was acute limb ischemia after thrombus embolization in eleven patients (79%), requiring surgical revascularization. Embolization occurred to the lower limb in 8 (73%) cases and the upper limb in the remaining 3 (22%). One patient presented with bilateral femoropopliteal embolization. Another patient presented with simultaneous acute myocardial infarction due to coronary embolization, although the thrombus was located in the descending thoracic aorta. Other presentations included acute mesenteric ischemia (n=1) and low back and flank pain from renal infarction (n=1). One patient was asymptomatic, and the aortic thrombus was an incidental finding. The diagnosis of PAMT was made by CT scan in all cases. CT scan findings during the clinical evolution of the patients demonstrated visceral vessel involvement in 6 patients (43%), some with multiple territories affected (renal, n=4; splenic n=3; liver n=1; mesenteric arteries n= 2). Major prothrombotic conditions were identified in eight cases (57%), including antiphospholipid syndrome (n=2), factor V Leiden mutation (n=1), mutation in the MTHFR C677T gene (n=1), Chron disease (n=1) and neoplasia (n=3), One patient had endometrial/ovarian carcinoma, and two patients had lung adenocarcinoma. Unfractionated heparin (UFH) was promptly started in all patients. Two patients developed heparin-induced thrombocytopenia (HIT), requiring changing therapy. Three patients underwent TEVAR for aortic thrombus exclusion. Recurrence of embolization/thrombosis was observed in four patients (29%), one treated with a TEVAR. We watched two deaths and one major amputation with a median follow-up time of 27 months (ranging from 1 to 60 months). One patient died after 39 days, secondary to multiple embolic events related to HIT. Another patient died at the end of 17 months due to the progression of neoplasia.

PAMT should be considered a differential diagnosis in patients with peripheral embolism without an identified cardiac embolic source. Although treatment with hypocoagulation alone is classically associated with high rates of thrombus resolution, the risk of recurrence of the embolic event cannot be underestimated. Endovascular treatment seems to be a good alternative for some high embolic risk patients, and the criteria for its use as a first-line still need to be defined. In our experience, the clinical presentation, anatomical factors such as the location and morphology of the thrombus, and the arterial territories affected should guide our decision. Our study also demonstrates the importance of closely monitoring patients treated with UFH for the risk of developing HIT with consequent outcomes.

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