Assessing the effectiveness of endografts: Clinical and experimental perspectives

MIDTERM RESULTS OF ENDOVASCULAR VERSUS OPEN SURGICAL REPAIR FOR INFRARENAL ABDOMINAL AORTIC ANEURYSMS IN LOW SURGICAL RISK PATIENTS

OBJECTIVE

To analyse midterm outcomes of endovascular repair (EVAR) versus open surgery (OR) for treatment of infrarenal abdominal aortic aneurysms (AAA) in low surgical-risk patients.

METHODS

Elective AAA patients undergoing treatment from 2003 to 2017 in a single, tertiary-care institution were evaluated. All patients with a low preoperative risk of complications and perioperative mortality (Medicare Aneurysm Scoring System <3) were included, and rates of perioperative and long-term mortality, adverse events and reintervention were evaluated for EVAR and OR. A propensity score matched cohort (PMC), levelling age, risk factors, and comorbidities was additionally performed.

RESULTS

A total of 227 patients were included (59.9% EVAR and 40.1% OR), and followed for a mean of 80 ± 48 months. Patients undergoing EVAR were older (66.6 ± 5 vs. 64.1 ± 6 years; p <.001, had a higher body mass index (29.6 ± 4 vs 28.1 ± 3; p = .005), a higher prevalence of COPD (27.3% vs 9.9%; p = .001) and lower prevalence of dyslipidaemia (46.3% vs 65.9%; p= .004). Patients undergoing OR had a higher rate of major adverse events (19.7% vs 2.6%, p = .001) and 30-day reinterventions (8.8% vs. 1.5%, p=.016), with 30-day mortality being 0% in both groups. The propensity-score matched cohort included 76 matched pairs (1:1), with differences in hospital-stay and major complications kept significant, without affecting mortality. At 5-year follow-up, there were no significant differences in the reintervention rate (18.5% EVAR vs 17.6% OAR; p = .67) or survival (85% EVAR vs 91% OR; p = .195).

CONCLUSION

In low surgical risk patients suffering from AAA, EVAR may offer comparable midterm results to open repair, with a lower rate of major adverse events and a shorter in-hospital stay. With the current OR-first paradigm in low-risk patients, several factors should be taken into account for decision making (anatomic suitability, risk of sexual dysfunction, risk of type 2 endoleaks and need of follow-up).

Thoracic aortic aneurysm. An experimental model in pigs

Purpose

To describe an unpublished experimental model of descending thoracic aortic aneurysm in pigs.

Methods

Ten Landrace female pigs aged 10 to 12 weeks old and with initial weights from 17 to 25 kg were anesthetized and their descending thoracic aortas exposed by fifth intercostal space left thoracotomy. The thoracic aorta was isolated. A 2-cm wide × 2-cm long patch of ready-made bovine pericardium was sewn onto the left anterolateral side of the aorta. After three weeks’ follow-up, a control aortography was taken, and the animals were euthanized. The segment of thoracic aorta containing the aneurysm and the adherent tissues were explanted en bloc. The specimens were stained for histological examination.

Results

One hundred percent of the animals survived the procedure, and after sacrifice a patent aneurysm was observed in all of them. There were no defects on the suture lines. Weight gain during follow-up was normal. All specimens exhibited intense adventitial reaction with myofibroblasts. There were no complications related to the thoracotomy.

Conclusions

The descending thoracic aortic aneurysms induced experimentally appear to be stable, were of easy execution, with null mortality and no influence on the animals’ normal development. Furthermore, they have similar characteristics to those observed in human degenerative aneurysms.

Comparable perioperative mortality outcomes in younger patients undergoing elective open and endovascular abdominal aortic aneurysm repair

BACKGROUND

Evidence for benefit of endovascular aneurysm repair (EVAR) over open surgical repair for de novo infrarenal abdominal aortic aneurysms (AAAs) in younger patients remains conflicting because of heterogeneous study populations and small sample sizes. The objective of this study was to compare perioperative and short-term outcomes for EVAR and open surgery in younger patients using a large national disease and procedure-specific data set.

METHODS

We identified patients 65 years of age or younger undergoing first-time elective EVAR or open AAA repair from the Vascular Quality Initiative (2003-2014). We excluded patients with pararenal or thoracoabdominal aneurysms, those medically unfit for open repair, and those undergoing EVAR for isolated iliac aneurysms. Clinical and procedural characteristics were balanced using inverse propensity of treatment weighting. A supplemental analysis extended the study to those younger than 70 years.

RESULTS

We identified 2641 patients, 73% (n = 1928) EVAR and 27% (n = 713) open repair. The median age was 62 years (interquartile range, 59-64 years), and 13% were female. The median follow-up time was 401 days (interquartile range, 357-459 days). Unadjusted perioperative survival was 99.6% overall (open repair, 99.1%; EVAR, 99.8%; P < .001), with 97.4% 1-year survival overall (open repair, 97.3%; EVAR, 97.4%; P = .9). Unadjusted reintervention rates were five (open repair) and seven (EVAR) reinterventions per 100 person-years (P = .8). After propensity weighting, the absolute incidence of perioperative mortality was <1% in both groups (open repair, 0.9%, EVAR, 0.2%; P < .001), and complication rates were low. Propensity-weighted survival (hazard ratio, 0.88; 95% confidence interval, 0.56-1.38; P = .6) and reintervention rates (open repair, 6; EVAR, 8; reinterventions per 100 person-years; P = .8) did not differ between the two interventions. The analysis of those younger than 70 years showed similar results.

CONCLUSIONS

In this study of younger patients undergoing repair of infrarenal AAA, 30-day morbidity and mortality for both open surgery and EVAR are low, and the absolute mortality difference is small. The prior published perioperative mortality and 1-year survival benefit of EVAR over open AAA repair is not observed in younger patients. Further studies of long-term durability are needed to guide decision-making for open repair vs EVAR in this population.

Regionalization of abdominal aortic aneurysm repair: evidence of a shift to high-volume centers in the endovascular era

INTRODUCTION

Since the early 1990s, many studies have shown lower mortality for abdominal aortic aneurysm (AAA) repair at high-volume centers compared with low-volume centers. The introduction of endovascular AAA repair (EVAR) also has changed the practice of AAA repair. The goal of this study was to determine if regionalization of AAA repair occurred in the United States. Etiologic factors were examined in addition to any reduction in operative mortality rates.

METHODS

Patient discharges of nonruptured AAA repair were identified from the Nationwide Inpatient Sample between 1998 and 2004. Hospitals were stratified by yearly AAA surgical volume of low (< or =17 cases), medium (18 to 50), and high (>50).

RESULTS

A total of 46,901 patients underwent AAA repair (72.7% open vs 27.3% endovascular). The percentage of AAA repairs performed at both low-volume (36.2% to 24.3%) and medium-volume (51.0% to 44.8%) centers fell; whereas, the percentage performed at high-volume centers nearly tripled (12.9% vs 30.9%). In 1998 there were 10 high-volume centers; by 2004 this had increased to 26. The number of low-volume centers decreased, from 412 to 328. EVAR was more rapidly adopted by high-volume centers compared with low-volume centers. By 2004, 64.3% of AAA repairs at high-volume centers were done with endovascular techniques compared with 31.8% in low-volume centers. A concurrent reduction occurred in patient mortality, from 4.4% in 1998 to 2.5% in 2004 (P < .0001).

CONCLUSION

Between 1998 and 2004, a trend towards the regionalization of AAA repair to high-volume centers occurred. Nearly one-third of all AAA repairs were performed at high-volume centers. There was a concurrent increase in the frequency of endovascular AAA repair, especially at high-volume centers. During this period of regionalization of AAA repair to high-volume centers, patient mortality after AAA repair decreased by 23%. Thus, the observed regionalization of AAA repair and the reduction in short-term patient mortality for this operation may be explained by increased utilization of endovascular technologies at high-volume centers.