Bilateral iliac artery aneurysms associated with higher reintervention and spinal cord ischaemia rates following complex EVAR

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Iliac artery aneurysms—affecting up to one third of patients with complex aortic aneurysms—do not affect all-cause mortality or aneurysm-related mortality in endovascular repair of complex aortic aneurysms, according to a study presented at the 2017 Vascular Annual Meeting (VAM; 30 May–3 June, San Diego, USA).

Presented by Jessica Zhang (Cleveland, USA) on behalf of her fellow Cleveland Clinic investigatorsincluding Matthew Eagletonthe study also found that bilateral iliac artery aneurysms are associated with a significantly higher reintervention rate and are potentially associated with a higher spinal cord ischaemia rate.

Despite the fact that 10–40% of all abdominal aortic aneurysms have iliac artery involvement, the incidence of their association with complex aortic aneurysms (juxtarenal and thoracoabdominal aortic aneurysms) is “less well-defined,” Zhang said. Associated iliac artery aneurysms can complicate management of complex aneurysms, and internal iliac artery preservation may be an important consideration in complex aneurysm treatment.

Zhang and colleagues evaluated the incidence, management and outcomes of iliac artery aneurysms associated with complex aneurysms treated with fenestrated or branched aortic endografts (FEVAR or BEVAR). The physician-sponsored investigational device exemption study ran from 2001 to 2016. For this study, iliac artery aneurysm was defined as common iliac artery ≥21mm as reported by a core lab. The team performed multivariable analysis of short- and long-term outcomes pre-/perioperatively (aneurysm characteristics, any prior repair, operating time), postoperatively (length of stay, use of mechanical ventilation and transfusions) and recorded any serious adverse events at 30 days.

In total, 1,118 repairs were analysed, 754 (67%) of which did not involve iliac artery aneurysms and 364 (33%) of which did. Of these, the most common repair type was type IV thoracoabdominal aortic aneurysm, accounting for 35.3% (n=395) of all treated aneurysms, 35% (n=138) of which involved iliac artery aneurysms and 65% (n=257) of which did not. The second most common repair type was type III thoracoabdominal aortic aneurysm, accounting for 25.1% (n=281) of all treated aneurysms, 36% (n=101) of which involved iliac artery aneurysms and 64% (n=180) of which did not.

While the two groups were largely demographically well-matched, there was a lower proportion of men in the no iliac artery aneurysm group (72%, n=545) than in the iliac artery aneurysm group (90%, n=328).

Of all patients with iliac artery aneurysms, 60% (n=219) were unilateral and 40% (n=145) bilateral. The mean iliac artery aneurysm size was 28mm and did not differ between the left (n=220) or right (n=289) side.

Of 509 iliac artery aneurysms, 234 (46%) underwent a common iliac seal (proximal aneurysm)—the most common treatment type in this cohort. A hypogastric branched endograft was used for 105 (21%) aneurysms, hypogastric coverage with embolisation for 103 (20%), and 67 (12%) were left untreated. Zhang noted that hypogastric branched devices and hypogastric coverage were more often used for the larger iliac artery aneurysms treated.

Procedures involving an iliac artery aneurysm were associated with a higher estimated median perioperative blood loss than those not involving one (600ml vs. 500ml; p<0.001), a longer total mean fluoroscopy time (76±39.67 vs. 88.8±43.2 minutes; p<0.001), and a longer mean procedure length (4.6±1.74 vs. 5.3±1.79 hours; p<0.001).

Zhang reported that there was no difference between the groups for all-cause mortality (unilateral p=0.907, bilateral p=0.147) or aneurysm-related mortality (unilateral p=0.58, bilateral p=0.14).

However, the data did indicate that complex EVAR with bilateral iliac artery aneurysms were associated with a significantly higher reintervention rate (hazard ratio 1.886 [1.42, 2.5] p<0.001) than in cases with unilateral or no iliac artery aneurysms.

The data also showed a potential relationship between bilateral iliac artery aneurysms and spinal cord ischaemia. The total spinal cord ischaemia rate for unilateral iliac artery aneurysms was 4.06%, for bilateral iliac artery aneurysms was 4.86%, and for no iliac artery aneurysms was 3.06%. However, when considering type II repairs, the rate of spinal cord ischaemia for bilateral iliac artery aneurysms was 21.43%, notably higher than for unilateral iliac artery aneurysms (4.14%) or for no iliac artery aneurysms (11.13%).

Reflecting on the data, Zhang concluded, “Additional efforts are needed to improve outcomes and understand the appropriate application of different treatment options for patients with complex aortic aneurysms.”

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