Comparison of Unibody and Non-Unibody Endografts for Abdominal Aortic Aneurysm Repair in Medicare Beneficiaries: The SAFE-AAA Study

Utilization and Outcomes Associated With Intravascular Ultrasound During Abdominal and Thoracic Endovascular Aortic Interventions in the United States in the Contemporary Era (2016-2023)

BACKGROUND

Intravascular ultrasound (IVUS) use in aortic endovascular interventions, including thoracic endovascular aneurysm repair (TEVAR) and endovascular aneurysm repair (EVAR), may have similar benefits to those seen in coronary and peripheral interventions, but limited utilization and outcome data exist.

METHODS

Centers for Medicare and Medicaid Services claims data were used to identify patients undergoing TEVAR and EVAR from 2016 to 2023. Utilization trends were stratified by region, urbanicity, distressed communities index, community versus academic center, Medicare versus dual enrollment status, indication, urgency, and presence of dissection with malperfusion. Inverse probability weighting was used to assess the impact of IVUS on a composite outcome of repeat aortic intervention or death. Cox regression was used to estimate weighted hazard ratios.

RESULTS

A total of 136 540 patients underwent TEVAR and EVAR, of which 9.8% (13 364) used IVUS. IVUS use increased slightly from 2016 to 2023, driven more by use in TEVAR compared with EVAR, and was higher in academic settings, with Medicare and Medicaid dual enrollment, in the West, with dissections, with malperfusion and for elective procedures. IVUS was associated with a lower risk of the primary outcome at 30-days (hazard ratio, 0.80 [95% CI, 0.73-0.89]; P<0.001) and 6-months (hazard ratio, 0.93 [95% CI, 0.87-0.99]; P=0.022) for all-comers. Subgroup analysis suggested lower risks of the primary outcome with IVUS use for aneurysm driven by the abdominal segment, malperfusion, thoracoabdominal dissection with malperfusion, thoracoabdominal repair, and chronic kidney disease.

CONCLUSIONS

IVUS use has increased slightly in TEVAR and EVAR with heterogeneity in use. IVUS implementation during TEVAR and EVAR was associated with improved early and mid-term outcomes, particularly in certain subsets.

Endovascular abdominal aortic aneurysm repair (EVAR) outcomes of unibody and single/double docking limb endografts in Medicare beneficiaries between 2012 and 2018

OBJECTIVE

The evaluation of perioperative and long term outcomes for endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAA) using anatomic (unibody) and proximal neck fixated (docking limbs) endografts across consecutive time cohorts.

DESIGN

This study compares the outcomes of EVAR in Medicare patients stratified by mode of fixation.

METHODS

All patients who underwent EVAR between 2012 and 2018 were identified in the Medicare database. Anatomic fixation (AF) and proximal fixation (PF) grafts were differentiated using Current Procedural Terminology (CPT) codes. The AF population was divided into three-time cohorts based on iterative changes in graft design: Cohort 1: (01/01/2012-20/07/2014); Cohort 2: (21/07/2014-09/05/2016); and Cohort 3: (10/05/2016-31/12/2017). The PF cohort was similarly divided into these three periods. Outcomes were evaluated through 31/12/2020 and included all-cause mortality, aortic rupture, and aortic-related reintervention.

RESULTS

32,031 patients underwent EVAR during the study period; 4729 were AF and 27,302 were PF. There were more women (p < .001) and patients with peripheral vascular disease (PVD) (p < .001) in the AF group. There were no group differences in perioperative outcomes. In Cohort 1, there was a higher rate of reintervention (11.9% vs 7.6%; p < .001) and aortic rupture (5.3% vs 4.0%; p = .019) in the AF group compared to the PF group. In Cohort 2, reintervention, aortic rupture, and reintervention rates were similar between the two groups (p = NS). In Cohort 3, the reintervention and aortic rupture rates were similar between the two groups (p = NS).

CONCLUSION

The higher rates of aortic rupture and reintervention seen in the AF group in Cohort 1 when compared with the PF group did not persist in Cohorts 2 and 3. This suggests that improvements in graft design may have led to durability which is similar to that of PF grafts. However, late aneurysm related complications are inherent risks after EVAR and long-term surveillance remains necessary.

Safety Evaluation of Unibody Endografts for Abdominal Aortic Aneurysm Repair: A Systematic Review and Meta-Analysis

BACKGROUND

The unibody bifurcated aortic endograft (AFX/AFX2) has emerged as a treatment option for abdominal aortic aneurysms (AAAs). This systematic review and meta-analysis aimed to evaluate the safety of the unibody endograft.

METHODS

A literature search was conducted in Cochrane Library, Scopus, Web of Science, and PubMed. Studies assessing the unibody endograft for AAA repair between 2014 and 2023 were included. The defined primary outcomes were the incidences of type I, II, and III endoleaks. The secondary outcomes were access site problems, aneurysm-related mortality, aneurysm rupture, all-cause mortality, aneurysm sac growth, limb occlusion, stent graft migration, and technical success rate.

RESULTS

Fourteen studies including 12 observational studies and 2 randomized controlled trials were included in the systematic review. The meta-analysis included 10 studies with 12,690 patients that reported the measured outcomes, and excluded 4 studies that did not. Type II endoleaks had the highest incidence of 12% (95% confidence interval [CI]: 4-20%), followed by type III endoleaks with an incidence of 3% (95% CI: 1-5%). The incidence of type I endoleaks was 1% (95% CI: 0-2%). A subgroup analysis by follow-up duration showed that type II endoleak incidence was higher after 1 to 2 years of follow-up than 3 to 4 years of follow-up. The incidence of aneurysmal mortality was 2% (95% CI: 0-7%), limb occlusion was 1% (95% CI: 0-1%), stent graft migration was 1% (95% CI: 0-2%), aneurysmal rupture was 6% (95% CI: 2-11%), access site problems were 7% (95% CI: 2-13%), aneurysm sac growth was 2% (95% CI: 0-4%), all-cause mortality was 21% (95% CI: 4-38%), and technical success rate was 100% (95% CI: 98-100%).

CONCLUSIONS

The unibody endograft is a safe and minimally invasive approach for AAA repair. However, potential complications necessitate close patient follow-up after the intervention.

Leveraging real-world data to conduct externally controlled trial for rare diseases with count-type endpoints: utilizing multiple entries - a simulation study

Conducting randomized controlled trials for medications targeting rare diseases presents significant challenges, due to the scarcity of participants and ethical considerations. Under such circumstances, leveraging real-world data (RWD) to generate supporting evidence may be accepted by the regulatory agency. Constructing an external control arm (ECA) from RWD for a single-arm trial has been conducted occasionally. A complication in this design is that patients from RWD may be eligible at multiple time points. Most studies approach this by selecting one time point as the index date for ECA patients. Here, we propose a novel design for externally controlled trials that permits the inclusion of ECA patients at various entry points. Accompanying this design, we make recommendations for statistical methods to account for measured confounders, limited sample size, within-subject correlation, and potential overdispersion inherent in count data. Furthermore, we present an idea for the blinding process for this type of study. We have conducted a series of simulations to assess the performance of the design and statistical methods in terms of bias, type I error, and efficiency, as compared to the approach of selecting only one entry per ECA patient. The study and parameter setup were based on a hypothetical case inspired by a rare disease study. The results indicate that allowing multiple entries for ECA patients can lead to enhanced performance in many aspects. It provides a controlled type I error, robustness against certain model misspecifications, and a moderate power improvement compared with selecting a single entry per ECA patient.

Device regulation and surveillance in vascular care: Challenges and opportunities

Cardiovascular devices are essential for the treatment of cardiovascular diseases including cerebrovascular, coronary, valvular, congenital, peripheral vascular and arrhythmic diseases. The regulation and surveillance of vascular devices in real-world practice, however, presents challenges during each individual product's life cycle. Four examples illustrate recent challenges and questions regarding safety, appropriate use and efficacy arising from FDA approved devices used in real-world practice. We outline potential pathways wherein providers, regulators and payors could potentially provide high-quality cardiovascular care, identify safety signals, ensure equitable device access, and study potential issues with devices in real-world practice.

Delayed migration due to shortening of the lower part of AFX endograft's main body in angled fusiform abdominal aortic aneurysm

We encountered two fusiform abdominal aortic aneurysm cases with delayed AFX endograft (Endologix Inc) migration >4 years after placement. These cases showed shortening and slight angulation of the main body in the anteroposterior direction. We speculate that the potential mechanism relates to the AFX portion that is easily shortened at the bifurcation of its stent structure. This portion might contribute to delayed migration after slight angulation of the main body. Preoperative three-dimensional computed tomography should be performed from the anteroposterior and lateral views. Although the AFX is useful for narrow bifurcations, one should consider the patient's anatomy before deciding to use an AFX endograft.