Midterm results of endovascular aneurysm sealing to treat abdominal aortic aneurysm

Mortality analysis of endovascular aneurysm sealing versus endovascular aneurysm repair

BACKGROUND

Endovascular aneurysm sealing (EVAS), using the Nellix endovascular aneurysm sealing system, has been associated with high reintervention and migration rates. However, prior reports have suggested that EVAS might be related to a lower all-cause mortality compared with endovascular aneurysm repair (EVAR). In the present study, we examined the 5-year all-cause mortality trends after EVAS and EVAR.

METHODS

We compared the 333 EVAS patients in the EVAS-1 Nellix U.S. investigational device exemption trial with 16,497 infrarenal EVAR controls from the Vascular Quality Initiative, treated between 2014 and 2016, after applying the exclusion criteria from the investigational device exemption trial (ie, hemodialysis, creatinine >2.0 mg/dL, rupture). As a secondary analysis, we stratified the patients by aneurysm diameter (<5.5 cm and ≥5.5 cm). We calculated propensity scores after adjusting for demographics, comorbidities, and anatomic characteristics and applied inverse probability weighting to compare the risk-adjusted long-term mortality using Kaplan-Meier and Cox regression analyses.

RESULTS

After weighting, the EVAS group had experienced similar 5-year mortality compared with the controls from the Vascular Quality Initiative (EVAS vs EVAR, 18% vs 14%; hazard ratio [HR], 1.1; 95% confidence interval [CI], 0.71-1.7; P = .70). The subgroup analysis demonstrated that for patients with an aneurysm diameter of <5.5 cm, EVAS was associated with higher 5-year mortality compared with EVAR (19% vs 11%; HR, 2.4; 95% CI, 1.7-4.7; P = .013). In patients with an aneurysm diameter of ≥5.5 cm, EVAS was associated with lower mortality within the first 2 years (2-year mortality: HR, 0.29; 95% CI, 0.13-0.62; P = .002). However, compared with EVAR, EVAS was associated with higher mortality between 2 and 5 years (HR, 1.9; 95% CI, 1.2-3.0; P = .005), with no mortality difference at 5 years (18% vs 17%; HR, 0.82; 95% CI, 0.4-1.4; P = .46).

CONCLUSIONS

Within the overall population, EVAS was associated with similar 5-year mortality compared with EVAR. EVAS was associated with higher mortality for those with small aneurysms (<5.5 cm). For those with larger aneurysms (≥5.5 cm), EVAS was initially associated with lower mortality within the first 2 years, although this advantage was lost thereafter, with higher mortality after 2 years. Future studies are required to evaluate the specific causes of death and to elucidate the potential beneficial mechanism behind sac obliteration that leads to this potential initial survival benefit. This could help guide the development of future grafts with better proximal fixation and sealing that also incorporate sac obliteration.

A Unique Indication for the Altura Endograft to Repair Bilateral Common Iliac Artery Aneurysms Associated with a Short-Infrarenal Aorta

A 71-year-old man with end-stage renal disease on hemodialysis presented with bilateral common iliac artery aneurysms diagnosed during the workup of his chronic kidney disease. On computed tomography angiography, common iliac artery aneurysm diameters measured 6.1 cm on the right side and 3.1 cm on the left side. The infrarenal aorta also had a small 3.2-cm aneurysm, but the length from the lowest left renal to the aortic bifurcation was only 6.7 cm, precluding use of most bifurcated endografts. Following an uneventful staged preoperative internal iliac artery embolization, a two-piece D -shaped Altura endograft for the aorta, with bilateral iliac components, landing at the level of the external iliac arteries was successfully performed. Postoperative course was uneventful with no endoleak or endograft migration on computerized tomographic angiography 45 days later, although billowing mimicking an endoleak was evident and will be closely followed.

Endovascular Aneurysm Sealing is Associated with Higher Medium-Term Survival than Traditional EVAR

BACKGROUND

Endovascular aneurysm repair (EVAR) is the dominant treatment modality for abdominal aortic aneurysm (AAA). Periprocedural risks are low, and cardiovascular events are the principle determinants of long-term survival. Recently, the concept of endovascular aneurysm sealing (EVAS) has been introduced into clinical investigation. In previous cohort studies, EVAS has been associated with a lower all-cause mortality than expected despite device issues. We used a propensity weighted approach to investigate whether EVAS was associated with lower all-cause mortality after aneurysm repair.

METHODS

We compared 333 patients in the Nellix United States Investigational Device Exemption trial to 15,431 controls from the Vascular Quality Initiative between 2014 and 2016 after applying the exclusion criteria from the investigational device exemption (hemodialysis, creatinine > 2.0 mg/dL, or rupture). We calculated propensity scores and applied inverse probability weighting to compare risk adjusted medium-term survival using Kaplan-Meier and Cox regression.

RESULTS

After weighting, patients treated with the Nellix EVAS system experienced higher 3-year survival than controls from the Vascular Quality Initiative (93% vs. 88%, respectively). This corresponded to a 41% lower risk of mortality for EVAS compared with EVAR (HR 0.59 [0.38-0.92], P = 0.02). Subgroup analysis demonstrated that the association between EVAS and higher survival was strongest in the subgroup of patients with aneurysms over 5.5 cm (P for interaction < 0.001). In this subgroup, EVAS patients experienced half the rate of mortality as those patients treated with EVAR, with 3-year survival of 92% compared with 86% (HR 0.5 [0.3-0.9], P = 0.02).

CONCLUSIONS

In this select group of patients, EVAS was associated with higher medium-term survival than traditional EVAR. Although issues with the device have recently surfaced, this exploratory analysis shows that the concept of sac sealing may hold promise. Further study is needed to confirm this finding and determine whether EVAS is associated with lower rates of cardiovascular events.

Cardiac Pulsatility- and Respiratory-Induced Deformations of the Renal Arteries and Snorkel Stents After Snorkel Endovascular Aneurysm Sealing

Purpose: To quantify deformations of renal arteries and snorkel stents after snorkel endovascular aneurysm sealing (Sn-EVAS) resulting from cardiac pulsatility and respiration and compare these deformations to patients with untreated abdominal aortic aneurysms (AAA) and snorkel endovascular aneurysm repair (Sn-EVAR). Materials and Methods: Ten Sn-EVAS patients (mean age 75±6 years; 8 men) were scanned with cardiac-gated, respiration-resolved computed tomography angiography. From 3-dimensional geometric models, changes in renal artery and stent angulation and curvature due to cardiac pulsatility and respiration were quantified. Respiration-induced motions were compared with those of 16 previously reported untreated AAA patients and 11 Sn-EVAR patients. Results: Renal artery bending at the stent end was greater for respiratory vs cardiac influences (6°±7° vs -1°±2°, p<0.025). Respiration caused a 3-fold greater deformation on the left renal artery as compared with the right side. Maximum curvature change was higher for respiratory vs cardiac influences (0.49±0.29 vs 0.24±0.17 cm^-1, p<0.025), and snorkel renal stents experienced similar maximum curvature change due to cardiac pulsatility and respiration (0.14±0.10 vs 0.19±0.09 cm^-1, p=0.142). When comparing the 3 patient cohorts for respiratory-induced deformation, there was significant renal branch angulation in untreated AAAs, but not in Sn-EVAR or Sn-EVAS, and there was significant bending at the stent end in Sn-EVAR and Sn-EVAS. Maximum curvature change due to respiration was ~10-fold greater in Sn-EVAR and Sn-EVAS compared to untreated AAAs. Conclusion: The findings suggest that cardiac and respiratory influences may challenge the mechanical durability of snorkel stents of Sn-EVAS; similarly, however, respiration may be the primary culprit for tissue irritation, increasing the risk for stent-end thrombosis, especially in the left renal artery. The bending stiffness of snorkel stents in both the Sn-EVAR and Sn-EVAS cohorts damped renal branch angulation while it intensified bending of the artery distal to the snorkel stent. Understanding these device-to-artery interactions is critical as they may affect mechanical durability of branch stents and quality and durability of treatment.