Clinical Comparison between Early and Late Spontaneous Sac Shrinkage after Endovascular Aortic Aneurysm Repair

The real-world incidence and predictors of sac regression in patients with infrarenal abdominal aortic aneurysm after standard EVAR

OBJECTIVE

Sac regression (SR) is a surrogate marker of satisfied endovascular aneurysm repair (EVAR). This research aims to investigate the incidence and predictors of SR in a Chinese population.

DESIGN

Single centre retrospective cohort study.

METHODS

Consecutive patients with infrarenal abdominal aortic aneurysms (AAAs) who underwent standard EVAR were retrospectively reviewed. SR was defined as sac shrinkage > 5 mm on computed tomography images, while major SR (MaSR) was ≥ 10 mm sac shrinkage. The cumulative rate was calculated by Kaplan-Meier analysis and predictors were identified by the Cox regression model.

RESULTS

A total of 469 patients (median age, 71 years old) were included. The majority of them (86.6 %) were male. With a median time of 13.6 months, SR was detected in 129 (27.5 %) patients after the index EVAR. Compared with never smokers, current smokers were more likely to experience SR (adjusted HR 2.630, p < .001), while former smokers did not show any significant difference. Multivariate Cox regression also showed that maximal aneurysm diameter (adjusted HR 1.012, p = 0.035) and female (adjusted HR 1.675, p = .045) were independent predictors of SR. A total of 51 (10.9 %) patients had MaSR at a median time of 15.4 months after EVAR. In multivariate analysis, maximal aneurysm diameter and Zenith stent graft were independently associated with MaSR.

CONCLUSION

In Chinese population, the incidence of SR and MaSR was 27.5 % and 10.9 % after EVAR, respectively. Maximal aneurysm diameter and female were independent predictors of SR. Compared with never smokers, it was more likely to have SR in current smokers.

Importance of sac regression after EVAR and the role of EndoAnchors

The initial success and widespread adoption of endovascular aneurysm repair (EVAR) for the treatment of abdominal aortic aneurysms have been tempered by numerous reports of secondary interventions and increased long-term mortality compared with open repair. Over the past decade, several studies on postoperative sac dynamics after EVAR have suggested that the presence of sac regression is a benign feature with a favorable prognosis. Conversely, increasing sacs and even stable sacs can be indicators of more unstable sac behavior with worse outcomes in the long-term. Endoleaks were initially perceived as the main drivers of sac behavior. However, the observation that sac regression can occur in the presence of endoleaks, and vice versa - increasing sacs without evidence of endoleak - on imaging studies, suggests the involvement of other contributing factors. These factors can be divided into anatomical factors, patient characteristics, sac thrombus composition, and device-related factors. The shift of interest away from especially type 2 endoleaks is further supported by promising results with the use of EndoAnchors regarding postoperative sac behavior. This review provides an overview of the existing literature on the implications and known risk factors of post-EVAR sac behavior, describes the accurate measurement of sac behavior, and discusses the use of EndoAnchors to promote sac regression.

Long-Term Outcomes of Simple Endovascular Aneurysm Repair Based on the Initial Aortic Diameter

PURPOSE

We aimed to investigate the effects of initial abdominal aortic aneurysm (AAA) diameter on aneurysmal sac expansion/shrinkage, endoleaks, and reintervention postelective simple endovascular aneurysm repair (EVAR).

METHODS

Overall, 228 patients monitored for >1 year after EVAR were analyzed. Male and female participants with initial AAA diameters <55 mm and <50 mm, respectively, composed the small group (group S), while those with initial AAA diameters ≥55 mm (men) and ≥50 mm (women) composed the large group (group L). Aneurysmal sac expansion of 10 mm and/or reintervention during follow-up (composite event) and its related factors were evaluated.

RESULTS

The 5-year freedom from composite event rate was significantly higher in group S (92.4 ± 2.8%) than that in group L (79.1 ± 4.9%; P <0.01). Multivariate analysis revealed AAA diameters before EVAR in group S (hazard ratio, 0.38; 95% confidence interval, 0.18-0.81; P = 0.01) and type II endoleak (T2EL) at discharge (hazard ratio, 2.83; 95% confidence interval, 1.29-6.20; P <0.01) as factors associated with the composite event. The freedom from composite event rate decreased to 51 ± 13% at 5 years in group L with T2EL.

CONCLUSIONS

Group S had high freedom from composite event rate; in group L, the rate decreased to 51% at 5 years with T2EL at discharge.

The Association Between the D-dimer Level at 1 Year After EVAR and Sac Diameter Change in Patients With Persistent Type 2 Endoleak

PURPOSE

Recent studies suggested that continuous clotting renewal in thrombi plays a central role in sac enlargement after endovascular aneurysm repair (EVAR). We reviewed patients with persistent type 2 endoleak (T2EL) to estimate the impact of D-dimer level on sac enlargement.

METHODS

A retrospective review of elective EVAR for infrarenal abdominal aortic aneurysm performed between June 2007 and February 2020. Persistent T2EL was defined as T2EL confirmed at both the 6 and 12 month contrast-enhanced computed tomography (CECT) follow-ups. "Isolated" T2EL was defined as T2EL without other types of endoleak within 12 months. Patients with >2 year follow-up, persistent isolated T2ELs, and D-dimer level data at 1 year (DD1Y) were included. Patients with any reintervention within 12 months were excluded. The association between DD1Y and aneurysm enlargement (AnE), defined as a ≥5 mm diameter increase, within 5 years was analyzed. Among 761 conventional EVAR, 515 patients had >2 years of follow-up. Thirty-three patients with any reintervention within 12 months and 127 patients without CECT at either 6 or 12 months were excluded. Among 131 patients with persistent isolated T2ELs, 74 patients with DD1Y data were enrolled. During a 37 month median follow-up [25-60, IQR], 24 AnEs were observed. In the AnE patients, the median DD1Y was significantly higher than that in the other patients (12.30 [6.88-21.90] vs 7.62 [4.41-13.00], P=0.024). ROC curve analysis indicated that the optimal cutoff point of DD1Y for AnE was 5.5 µg/mL (AUC=0.681). In univariate analysis, angulated neck, occlusion of the inferior mesenteric artery, and DD1Y≥5.5 µg/mL were significantly associated with AnE (P= 0.037, 0.038, and 0.010). Cox regression analysis revealed that DD1Y≥5.5 µg/mL was correlated with AnE (P=0.042, HR [95% CI] 4.520 [1.056-19.349]).

CONCLUSION

A 1 year higher D-dimer level can potentially predict AnE within 5 years in persistent T2EL patients. AnE was considered improbable when the D-dimer level was low enough.

CLINICAL IMPACT

The present study suggests that a 1-year higher D-dimer level could potentially predict aneurysm expansion within 5 years in patients with persistent type 2 endoleak (T2EL). On the other hand, aneurysm expansion was considered unlikely if the D-dimer level was low enough.As there are many patients with T2EL who require regular follow-up, any predictor of future aneurysm expansion could be of great help in conserving medical resources. In patients with a low likelihood of future expansion, we might consider delaying follow-up, similar to patients with sac shrinkage.

One-year sac regression is associated with freedom from fatal adverse events after endovascular aneurysm repair

OBJECTIVE

Although the predictors of long-term prognosis after endovascular aneurysm repair (EVAR) have been investigated, several reports have suggested that early sac shrinkage (ESS) is associated with superior long-term prognosis. However, it was not clear whether ESS was associated with aneurysm-related mortality. The aim of this study was to define fatal adverse events and to examine their association with ESS.

METHODS

All consecutive patients who underwent EVAR for an abdominal aortic aneurysm at Nagoya University Hospital between June 2007 and August 2018 were identified. We defined ESS as an aneurysm diameter decrease of 10 mm or more at 1 year after EVAR, and we defined fatal adverse events as aneurysm-related death, aneurysm sac rupture, open conversion, secondary type Ia endoleak, or secondary type IIIa/b endoleak. Then, we evaluated the association between ESS and fatal adverse events and identified predictors of ESS.

RESULTS

During the study period, 553 patients were identified and included. Fatal adverse events occurred in 42 patients (7.6%), and the details of the fatal adverse events were as follows: 13 aneurysm-related deaths, 17 aneurysm sac ruptures, 14 open conversions, 13 type Ia endoleaks, and 6 type III endoleaks. ESS occurred in 146 patients (26.4%). Kaplan-Meier curves showed that the ESS group had a significantly lower incidence of fatal adverse events (P < .001). Multivariate analysis showed that there were significant differences in terms of 5 or more preoperatively patent lumbar arteries (odds ratio [OR], 0.67; P = .049; 95% confidence interval [CI], 0.45-1.00), chronic kidney disease (OR, 0.49; P < .01; 95% CI, 0.29-0.84), and Zenith endograft use (OR, 1.76; P < .01; 95% CI, 1.16-2.67). Furthermore, the percentage of cases that achieved an aneurysm diameter of less than 40 mm was significantly higher in the ESS group (76.0% vs 15.5%; P < .01). The use of Zenith endografts showed a significantly higher rate of aneurysm disappearance than the use of Endurant endografts (P < .01) and Excluder endografts (P < .01). In addition, it was found that ESS was more likely to occur with the use of Zenith endografts, even when propensity score matching was performed for the neck morphology.

CONCLUSIONS

ESS was associated with a lower rate of life-threatening adverse events after EVAR. The use of Zenith endografts was a predictor of ESS and was associated with increased rates of long-term sac shrinkage and aneurysm disappearance compared with the Endurant and Excluder endografts. Using the predictors of ESS identified in this study, we may be able to expand the indications for EVAR to patients with a longer life expectancy.

Factors Associated With Spontaneous Sac Shrinkage in Patients With Persistent Type 2 Endoleaks After EVAR

PURPOSE

Despite controversy surrounding the management of type 2 endoleaks (T2ELs) after endovascular aortic aneurysm repair (EVAR), the current European guidelines recommend reintervention for T2ELs when the aneurysm expands by ≥10 mm. Meanwhile, sac shrinkage ≥10 mm can be considered low risk for failure even with T2ELs, and the guidelines suggest less frequent follow-up delayed until 5 years after EVAR. This study reviewed patients with persistent T2ELs to identify predictors of spontaneous sac shrinkage (SpS) within 5 years.

METHODS

A retrospective review of elective EVAR for infrarenal aortic aneurysms between June 2007 and December 2017. Patients with >1 year follow-up and persistent T2ELs, defined as T2ELs confirmed at both the 6 and 12 month follow-up with contrast-enhanced computed tomography (CT), were included. Any reintervention or type 1 or 3 endoleaks within 12 months were excluded. SpS was defined as a ≥10 mm reduction in diameter without any reintervention. Aneurysm enlargement (AnE) was defined as a ≥5 mm increase in diameter. Factors associated with SpS within 5 years were analyzed. The clinical outcomes were reviewed.

RESULTS

Among 726 patients, 162 patients had persistent isolated T2ELs. After excluding 21 patients, 141 patients were enrolled. During a median follow-up of 43 months (interquartile range [IQR], 26-60), 28 SpS and 39 AnE were observed, and 31 reinterventions were performed. The cumulative rates of SpS were 14.2%±2.9% and 25.6%±5.1% at 1 and 5 years. Cox regression analysis revealed that the presence of ≥6 patent lumbar arteries had a significant negative correlation with SpS (p=0.036). During further follow-up after SpS, 2 reinterventions for type 1a and 3b endoleaks were required at 49 and 45 months.

CONCLUSIONS

Patients with fewer patent lumbar arteries were likely to experience SpS within 5 years, even in the presence of persistent T2ELs. Follow-up imaging studies were advisable earlier than 5 years, even after SpS.