Adverse Neck Anatomy Increases Risk of Late Type 1A Endoleaks

Type 1A endoleaks (those that originate from the proximal seal zone) are the most common cause of late rupture and the need for open conversion after endovascular aneurysm repair (EVAR). Late proximal endoleaks are especially concerning because of high potential for rupture.

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Mark F. Conrad, MD, MMSc, director of Clinical Research in the Division of Vascular and Endovascular Surgery, Thomas F.X. O'Donnell, MD, in the Division of Vascular and Endovascular Surgery, both at Massachusetts General Hospital, and colleagues conducted the first study that had a sufficiently large sample and follow-up to characterize late proximal endoleaks. Their findings appear in Annals of Vascular Surgery.

Study Cohort

This was a retrospective study of prospectively collected data on 411 patients without prior aortic surgery who underwent elective infrarenal EVAR at Mass General between 2010 and 2018 and had at least one postoperative CT angiogram (CTA).

Incidence

24 type 1A endoleaks were identified:

• Four early (on the one-month postoperative CTA)
• 20 late (≥one year after stent implantation and not diagnosed previously)

Late endoleaks appeared with a median of 2.9 years after the procedure (range, 1.1–8.3 years).

Risk Factors

Ten of the 20 patients who developed late type 1A endoleaks had adverse anatomy (outside the manufacturer's instructions for use with respect to the aneurysm neck).

Independent and significant risk factors for late type 1A endoleaks were:

• Older age (HR=1.07 per year)
• Neck diameter >28 mm (HR=3.5)
• Neck length <20 mm (HR=3.0)
• Neck angle >60° (HR=3.4)

Findings on Completion Angiogram

• 60% of patients who later developed late type 1A endoleak had no endoleak at all on completion angiography (at the end of surgery)
• Only 10% of patients who developed a late type 1A endoleak had a type 1A endoleak on completion of angiography

Findings on One-Year CTA

• Four patients had a late type 1A endoleak on the one-year CT
• Aneurysm sac size had failed to regress in 15 patients—it remained stable in 11 and had expanded in four
• In the other four patients, the aneurysm sac had regressed, which usually indicates a successfully treated aneurysm, but two patients later experienced graft migration

Other Key Findings

• 65% of patients with late type 1A endoleaks, versus only 15% of those without, had previously undergone at least one reintervention (P<0.001)
• Two of the 20 patients with late type 1A endoleaks (10%) experienced aortic rupture, one from proximal degeneration and one from graft migration
• Median survival after diagnosis of a late Type 1A endoleak was 6.6 years (range, 0 days to 8.2 years)

Clinical Pearls

• Some late type 1A endoleaks are new leaks appearing because of late changes in the aorta or loss of seal over time, not undiagnosed leaks that were present at implantation
• Most patients with late endoleaks had sacs that failed to regress within one year, underscoring the need for continued follow-up
• Open repair or fenestrated/branched devices should be considered for patients with adverse anatomy; if EVAR is conducted, the patient probably warrants especially close follow-up, even years out from the procedure
• Careful surveillance for late type 1A endoleak is also needed for any patient who undergoes reintervention after EVAR

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