Safety and Long-Term Patency of Endovascular Therapy for Infrarenal Aortic Disease: Single-Center Experience and Review of the Literature

Abstract: Objectives. Endovascular therapy (EVT) has emerged as an alternative to surgery for the treatment of symptomatic infrarenal aortic stenosis (IAS). However, long-term outcomes with EVT are unknown. Methods. We performed a retrospective review of patients with IAS treated with the endovascular approach at the University of Toledo Medical Center, Toledo, Ohio. We compared our single-center study (SCS) with a review of published studies (ROS) regarding complications, patency rate (PR), and repeat intervention rate (RIR). Pearson’s Chi-square or Fisher’s exact test, and the Student’s t-test or Mann-Whitney U-test, were used for categorical and continuous variables, respectively. For the ROS data, we used a pooled mean of means. Results. A total of 25 patients from the SCS were compared with 698 patients from the ROS data. Mean age was 63 years vs 58 years, females comprised 48% vs 54%, Rutherford class 3 comprised 68% vs 69%, and mean follow-up duration was 67 months vs 44 months in SCS vs ROS, respectively. PR at 12 months was 96% vs 90%, while PR at maximum time-period was 92% vs 76% in SCS vs ROS, respectively. RIR in SCS was 4% at 12 months and 8% at the maximum time period (20.2 years). RIR in ROS was 24% at the maximum time period (10 years). The mortality rate was 0% in the SCS arm vs 3.4% in the ROS arm. Conclusion. EVT is highly effective and safe, and was associated with excellent patency rates at long-term follow-up.

J INVASIVE CARDIOL2020;32(5):194-200.

Key words: clinical success, complications, endovascular treatment, infrarenal aortic stenosis, patency rate, technical success

Isolated occlusion or stenosis of the infrarenal aorta is a rare form of peripheral artery disease, with an estimated prevalence of 0.15%.¹ Most often the infrarenal aortic stenosis (IAS) is due to an atherosclerotic disease process that tends to involve the infrarenal portion of the abdominal aorta and may extend into the iliac arteries. Clinical presentation of IAS can include claudication and critical limb ischemia.^2,3 Several case series and single-center studies have reported the safety and efficacy of endovascular therapy (EVT) for IAS.⁴ EVT is favored as it is minimally invasive and associated with improved quality of life, lower complication rates, shorter hospital stay, and comparable long-term patency rates.^5,6 On the other hand, open surgical repair has a high mortality rate of up to 4.4% and other morbidities, such as infection rates of 0.5%-5%.^7,8 One study reported surgical bypass had a 5-year patency rate of 91% for patients with claudication and 87% for patients with critical ischemia.⁹ Postoperative complications of aortic reconstruction were 20%.¹⁰

Due to the rarity of IAS and lack of clinical data, the long-term patency rate with EVT continues to be unknown. Considering this, we aim to report our single-center experience on the clinical presentation and the endovascular management of IAS patients. We also provide an extensive review of the published literature on IAS and discuss clinical manifestations, technical success rates, patency rates, and complications of EVT. 

Methods

The protocol was written by the principal investigator (MAM) and further reviewed and updated by the senior author (MS). Institutional review board approval was obtained.

Inclusion and exclusion criteria. We included all patients with IAS who underwent EVT at the University of Toledo Medical Center, Toledo, Ohio. We did a systematic review of literature from January 1, 1990 to October 10, 2018. We excluded all studies describing patients <18 years old and with aortic lesions that extended above the renal arteries. The review of studies (ROS) included case series, retrospective studies, and prospective observational studies. Studies published before 1990, case reports, and studies published in languages other than English were excluded.

Search strategy and study selection. The single-center study (SCS) data were collected by one author (MAM). The ROS data review was conducted per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two reviewers (MA and MAM) independently conducted a search of PubMed, Medline, Cochrane, and Google Scholar using multiple search terms, words, and synonyms without any language restriction from January 1, 1990 to October 10, 2018. Medical subject headings (MeSH) used were distal aortic stenosis OR distal aortic occlusion OR infrarenal aortic stenosis OR infrarenal aortic occlusion OR endovascular treatment of aortic stenosis. We screened all article titles and abstracts and removed studies published in languages other than English. A third reviewer (SM) then independently reviewed these articles screened by the first two reviewers for the final inclusion in our ROS. The ROS data were collected by a fourth reviewer (CM).

SCS data collection. The University of Toledo Medical Center maintains a database for patients with lower-extremity peripheral artery disease that we used for our search from January 1990 through January 2018. We also used billing codes to maximize our search for patients with IAS. For data collection, we reviewed both paper and electronic medical records. Variables collected included demographics, clinical presentation, Rutherford classification, results of non-invasive diagnostic testing, procedural details, and outcomes. Angiographic and non-invasive test details were evaluated by two board-certified interventional cardiologists. The lesion lengths were noted. We identified 25 patients with infrarenal aortic stenosis or occlusion who underwent EVT during this time period.

ROS data collection. ROS data were collected from published articles on IAS from January 1, 1990 through October 10, 2018.^11-30 Variables similar to SCS were collected. We also included the year of publication, design of the study, place of study, and the total duration of study follow-up. After extensive screening and search, we obtained full-text copies of 33 studies of IAS undergoing EVT. A total of 23 studies with 698 patients were identified for final data analysis. 

Technical success was defined as <30% residual stenosis or mean translesional gradient of <10 mm Hg.¹¹ Clinical patency was defined as improvement or complete resolution of symptoms after the endovascular procedure. In addition, patency was followed with ankle-brachial index (ABI) measurements at 4 weeks, 6 months, and 12 months. Electronic medical records and paper charts were reviewed for complications and symptoms at follow-up. Major or minor amputations were included in outcomes. Decisions for repeat intervention based on symptoms, repeat ABI, or duplex studies were also collected from the databases, electronic medical records, and patient charts. We included data on repeat intervention rate at any period. Reasons for repeat interventions were also included in this data analysis. Mean follow-up duration was 67 months.

Statistical analysis. We used Statistical Package for the Social Sciences, version 20.0 (SPSS) for data analysis. Categorical data were described by frequency and percentage. We used mean and standard deviation for patient characteristic description. We used Pearson’s Chi-squared or Fisher’s exact test for categorical variables, and the Student’s t-test or Mann-Whitney U-test for continuous variables. A P-value of <.05 was considered statistically significant. For the ROS data, we used a pooled mean of means. Kaplan-Meier curve was used to assess cumulative patency of EVT for IAS.

Results

Demographic data. Table 1 describes the baseline demographics of the SCS and ROS. Patients in the SCS had a mean age of 63 years and 48% were women. The majority of patients had traditional risk factors for atherosclerotic disease, including hypertension (95%), hyperlipidemia (87%), and smoking (74%). Similar demographics were noted in the ROS group. The majority of patients presented with severe claudication. Mean follow-up duration in the SCS was 67 months (range, 3 months to 20.2 years) compared with a mean follow-up period of 44 months (range, 7 months to 10 years) in the ROS.

Interventional details for SCS. Board-certified interventional cardiologists at the University of Toledo Medical Center performed the endovascular procedures. All 25 procedures included in the study were performed by three highly experienced cardiovascular interventionists. More than 80% of the procedures were performed by someone with more than 30 years of experience in peripheral interventions. The other two operators had more than 5 years of experience in peripheral interventions. All peripheral interventions were performed via femoral access. Angiography was performed under conscious sedation. Heparin was used as an anticoagulant with a target activated clotting time of 250 seconds. In stenotic lesions, the translesional gradient was measured at baseline. Intra-arterial nitroglycerin was administered in borderline cases. Lesions were treated in standard fashion with balloon angioplasty followed by placement of stent(s). Choice of stent was entirely at the discretion of the treating physician. A total of 35 stents were placed in 28 patients with IAS. The majority were balloon-expandable stents (Table 2). Stents deployed included the Express LD (Boston Scientific); Omnilink (Abbott Vascular); Palmaz, Corinthian, Genesis, and Smart (Cordis); and Intrastent (Intratherapeutics). No covered stents were used. Only 1 patient had balloon angioplasty without stenting. Unfortunately, that patient was lost to follow-up. Fourteen patients had concomitant iliac artery stenting. Among patients with iliac artery stenting, nine patients had bilateral treatment. A variety of techniques were used for an infrarenal aortic disease that extended into the iliac arteries. If the lesion involved only the aorta, then balloon dilation followed by stent placement was utilized (Figure 1). However, if the lesion extended to the iliac arteries, the kissing-balloon technique was used to deploy stents. In some cases, in both iliac arteries, a “double-barrel” technique was used, extending iliac stents into the aorta. Among bilateral iliac artery stenting cases, four patients had double-barrel technique and 2 patients had kissing-stent technique. After stent deployment, a translesional gradient was remeasured to assess for technical success. All patients received daily aspirin 81 mg indefinitely. Clopidogrel 75 mg daily was typically used for a minimum of 3 months. 

Interventional details for ROS. In ROS, stenting of infrarenal aorta lesions was reported in all except 2 studies that described balloon angioplasty alone. A variety of stents were used, however, Palmaz and Wallstent (Boston Scientific) were the predominant stents utilized (Table 3). The involvement and EVT of concomitant iliac artery disease were described in 20 studies. Among these 20 studies, seventeen reported EVT of iliac artery stenosis along with IAS treatment. Moreover, among 17 studies, five had only balloon dilation of iliac artery stenosis and the rest had balloon dilation followed by stenting. Similarly, a variety of techniques were used for EVT of combined infrarenal aorta and iliac artery atherosclerotic disease, including kissing-balloon technique, double-barrel technique, and focal dilation followed by stent placement. The balloon dilation followed by stent placement was performed in 91% of patients. However, only 9% of patients had balloon dilation alone and no separate follow-up data were provided for these patients.

Lesion characteristics. In our SCS arm,  the mean preprocedural ABI was 0.75 ± 0.32 and mean postprocedural ABI was 1.09 ± 0.08 (P=.01). Mean preprocedural translesional gradient was 44 mm Hg, and mean postprocedural translesional gradient was 1.69 mm Hg (P=.01). In the ROS arm, mean preprocedural ABI was 0.65 ± 0.05 with a mean postprocedural ABI of 0.95 ± 0.06. The majority of studies in the ROS did not report translesional gradient. Mean aortic lesion length was 40 mm in the SCS arm vs 30 mm in the ROS arm. Aortic stenosis severity was 75% in the SCS arm vs 80% in the ROS arm  (Table 4). 

Study outcomes. The technical success rates were 100% in the SCS arm vs 94% in the ROS arm. The clinical success rates were 100% in the SCS arm vs 89% in the ROS arm. The clinical patency rate at 12 months was 96% in the SCS arm (Figure 2) vs 90% in the ROS arm. The patency rate at maximum follow-up was 92% in the SCS arm vs 76% in the ROS arm. Repeat intervention rate in the SCS arm was 4% (1 patient) at 12 months vs 8% (2 patients) at a maximum time period up to 20.2 years. These patients underwent EVT with repeat stenting. Repeat intervention rate in the ROS arm was 24% at a maximum time period (up to 10 years); 12-month reintervention rates were not available. The periprocedural complications rate was 0% in the SCS arm vs 8% in the ROS arm (Table 4). Similarly, the overall mortality rates were 0% at 67 months in the SCS arm vs 3.4% at 42 months in the ROS arm.

Discussion

Our study represents the largest data review on IAS treated with EVT. In our review, a total of 698 patients with IAS with or without iliac artery involvement were treated endovascularly. IAS tends to affect relatively young patients. The predominant stent type utilized was balloon-expandable stents followed by self-expanding stents. Covered stents were less frequently utilized. Although we did not use covered stents in our SCS cohort, we still achieved a patency rate of 96% at 1 year and 92% at a maximum time period of up to 20.2 years of follow-up. Our repeat intervention rate was low (8%) at a maximum time period of up to 20.2 years vs 24% in the ROS arm.

EVT in IAS is safe and associated with durable technical and clinical success rates. Surgical techniques, including endarterectomy and bypass grafting, have a similar patency rate (86.3% at 5 years).³¹ Complication rates of up to 12.2% and mortality rates of up to 4.4% have been reported in a meta-analysis of surgical graft interventions.⁷ Another review reported a 9.8% rate of late complications, including postsurgical adhesions and incisional hernia.³² In view of these findings, EVT has emerged as an alternative approach to treat IAS. 

Although EVT is safer than open surgery, complications were seen in 8% of patients in the ROS arm. Complications including vessel wall rupture (2%), distal embolization requiring embolectomy (2%), and large hematoma (6.1%) have been reported.^25,26 With advancements in EVT, the complication rates may drop further. In addition, EVT is associated with significantly lower mortality compared with surgery. In our SCS and ROS arms, the immediate periprocedural mortality rate was 0% and continued to be low at 12-month follow-up.

Repeat intervention due to restenosis is well known after EVT. In our SCS arm, the repeat intervention rate was only 4% at 12-month follow-up. Repeat intervention rates at 12 months were not available for the ROS arm.

Study limitations. This study is retrospective in nature, which creates inherent shortcomings in terms of the variables that can be analyzed and the inferences that can be drawn. There is limited information on delayed complications, restenosis, and mortality. We were unable to obtain ABIs and pressure gradients for the ROS arm. Also, the ROS arm had a relatively small number of patients and variable follow-up periods. Hence, it is difficult to make inferences from these studies. However, IAS is an uncommon disease entity and it is unlikely that a randomized clinical trial can be conducted. In this regard, our extensive review provides a comprehensive evaluation of the safety and durability of EVT for infrarenal aortic stenosis. 

Conclusion

Endovascular therapy for infrarenal aortic stenosis is safe and associated with high technical success and durable clinical success. EVT continues to be associated with much lower complication rates as compared with the surgical treatment of IAS. EVT now stands as a reasonable alternative to surgery for treatment of IAS.

From the Department of Medicine, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted October 22, 2019, provisional acceptance given December 3, 2019, final version accepted December 23, 2019.

Address for correspondence: Mark W. Burket, MD, Professor of Medicine, University of Toledo College of Medicine and Life Sciences, 3065 Arlington Avenue, Toledo, OH 43614. Email: mark.burket@utoledo.edu 

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