Spontaneous Inferior Mesenteric Artery Occlusion after Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm and its Impact on Clinical Outcomes.

Objective: The incidence and related factors of spontaneous occlusion of a patent inferior mesenteric artery (IMA) after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) without pre-emptive embolisation remain unclear. This study aimed to elucidate the incidence, clinical implications, and predictors of spontaneous IMA occlusion after EVAR.

Methods: This was a single centre, retrospective cohort study. Patients who underwent elective EVAR between 2007 and 2022 were categorised into three groups (group 1, spontaneous IMA occlusion; group 2, patent IMA with no type II endoleak [T2EL] from IMA; group 3, T2EL from IMA). Endpoints were the incidence of spontaneous IMA occlusion, sac enlargement, freedom from re-intervention, and overall survival after EVAR.

Results: Of 372 cases of elective EVAR for AAA, 230 who had patent IMA pre-operatively were analysed, after excluding 127 with pre-occluded IMA and 15 who underwent pre-emptive IMA embolisation. Spontaneous IMA occlusion occurred in 101 patients (43.9%). The sac enlargement rate was lower in group 1 than in groups 2 and 3. The freedom from re-intervention rate was higher in group 1 than in group 3 but did not differ between groups 1 and 2. Multivariable analysis revealed the absence of antiplatelet therapy, pre-operative higher haematocrit, absence of concomitant iliac artery aneurysm, posterior thrombus in the sac, and use of Endurant as predictors associated with spontaneous IMA occlusion. Spontaneous IMA occlusion was observed in 7.1% and 77.5% of patients with zero and four or five predictors, respectively.

Conclusions: Spontaneous IMA occlusion occurred in nearly half of cases and was associated with positive clinical outcomes. In patients with a high prediction of spontaneous IMA occlusion, pre-emptive IMA embolisation may be omitted.