Preoperative Intrasac Thrombus Load Predicts Worse Outcome after Elective Endovascular Repair of Abdominal Aortic Aneurysms

Thrombosis in the pathogenesis of abdominal aortic aneurysm

Background

Abdominal aortic aneurysms (AAAs) are a relatively common vascular pathology of the elderly with high morbidity potential. Irreversible degeneration of the aortic wall leads to lethal rupture if left untreated. Nearly all AAAs contain intraluminal thrombus (ILT) to a varying degree, yet the mechanisms explaining how thrombosis is disturbed in AAA are relatively unknown. This review examined the thrombotic complications associated with AAA, the impact of thrombosis on AAA surgical outcomes and AAA pathogenesis, and the use of antithrombotic therapy in the management of this disease.

Methods

A literature search of the PubMed database was conducted using relevant keywords related to thrombosis and AAAs.

Results

Thrombotic complications are relatively infrequent in AAA yet carry significant morbidity risks. The ILT can impact endovascular aneurysm repair by limiting anatomic suitability and influence the risk of endoleaks. Many of the pathologic mechanisms involved in AAA development, including hemodynamics, inflammation, oxidative stress, and aortic wall remodeling, contain pathways that interact with thrombosis. Conversely, the ILT can also be a source of biochemical stress and exacerbate these aneurysmal processes. In animal AAA models, antithrombotic therapies have shown favorable results in preventing and stabilizing AAA. Antiplatelet agents may be beneficial for reducing risks of major adverse cardiovascular events in AAA patients; however, neither antiplatelet nor anticoagulation is currently used solely for the management of AAA.

Conclusions

Thrombosis and ILT may have detrimental effects on AAA growth, rupture risk, and patient outcomes, yet there is limited understanding of the pathologic thrombotic mechanisms in aneurysmal disease at the molecular level. Preventing ILT using platelet and coagulation inhibitors may be a reasonable theoretical target for aneurysm progression and stability; however, the practical benefits of current antithrombotic therapies in AAA are unclear. Further research is needed to demonstrate the extent to which thrombosis impacts AAA pathogenesis and to develop novel pharmacologic strategies for the medical management of this disease.

Incidence and Fate of Refractory Type II Endoleak after EVAR: A Retrospective Experience of Two High-Volume Italian Centers

Introduction: The aim of the present study is to report the outcome of patients presenting an isolated type II endoleak (TIIEL) requiring reintervention and to identify clinical and anatomical characteristics potentially implicated in refractory TIIEL occurrence and fate. Materials and Methods: A multicenter retrospective study on TIIEL requiring reintervention was conducted between January 2003 and December 2020. Demographic and clinical characteristics, procedural technical aspects, reinterventions, and outcomes were recorded. TIIEL determining sac expansion greater than 10 mm underwent a further endovascular procedure aiming to exclude aneurismal sac. Redo endovascular procedures were performed via endoleak nidus direct embolization and/or aortic side branches occlusion. TIIELs responsible for persisting aneurysmal sac perfusion 6 months after redo endovascular procedures were classified as “refractory” and submitted to open conversion. Results: A total of 102 TIIEL requiring reintervention were included in the final analysis. Eighty-eight (86.27%) patients were male, the mean age was 77.32 ± 8.08 years, and in 72.55% of cases the American Society of Anaesthesiologists (ASA) class was ≥3. The mean aortic diameter was 64.7 ± 14.02 mm, half of treated patients had a patent inferior mesenteric artery (IMA), and 44.11% ≥ 3 couples of patent lumbar arteries (LA). In 49 cases (48.03%) standard endovascular aneurysm repair (EVAR) procedure was completed without adjunctive maneuvers. All enrolled patients were initially submitted to a further endovascular procedure once TIIEL requiring reintervention was diagnosed; 57 patients underwent LAs or IMA embolization (55.87%), 42 transarterial aneurismal sac embolization (41.17%), and three (2.96%) laparoscopic ostial ligations of the inferior mesenteric artery. During a mean follow-up of 15.22 ± 7.57 months (7−48), a redo endovascular approach was able to ensure complete sac exclusion in 52 cases, while 50 patients presented a still evident refractory TIIEL and therefore a surgical conversion or semiconversion was conducted. At the univariate analysis refractory TIIEL patients were significantly different from those who did not develop the complication in terms of preoperative clinical, morphological characteristics, and initial EVAR procedures: coronary artery disease occurrence (p = 0.005, OR: 3.18, CI95%: 1.3−7.2); preoperative abdominal aortic aneurysm (AAA) sac diameter (p = 0.0055); IMA patency (p = 0.016, OR: 2.64, CI95%: 1.18−5.90); three or more patent LAs; isolated standard EVAR without adjunctive procedures (p > 0.0001; OR: 9.48, CI95%: 3.84−23.4). Conclusions: Our experience seems to demonstrate that it is reasonable to try to preoperatively identify those patients who will develop a refractory TIIEL after EVAR and those with a TIIEL requiring reintervention for whom a simple endovascular redo will not be enough, needing surgical conversion.

Comparison of Outcomes Following EVAR Based on Aneurysm Diameter and Volume and Their Postoperative Variations

PURPOSE

to evaluate the impact of bi- and 3-dimensional preoperative aortic morphological features and their immediate postoperative variations on the outcome of abdominal aortic aneurysms (AAA) treated by endovascular exclusion with standard devices (EVAR).

MATERIALS AND METHODS

Double centre retrospective analysis of prospectively collected registry data of EVAR patients. For all patients, preoperative and 30-day computed tomographic angiography images (CTA) were reviewed. Preoperative maximum AAA diameter >59 mm and volume >159 cm³, and any 30-day postoperative increasing at CTA, were considered as potentially influencing the outcome. The outcome measures were: primary technical success; 30-day, 1-year, and mean follow-up reintervention, all-cause and AAA-related mortality rates, and also endoleak-related reinterventions.

RESULTS

Three hundred and thrity-three patients were enrolled. Mean preoperative and 30-day AAA diameter and volume were 50.4 mm ± 11.8 vs. 49.1 mm ± 12.1, and 112.9 cm3 ± 79.5 vs. 112.1 cm3 ± 80.5, respectively. Primary technical success was achieved in all cases. At 34.9 months follow-up, cumulative reintervention rate was 12.0%, mortality rates 7.2%, without AAA-related deaths. Endoleak-related reintervention rate was 7.5%. At uni- and multi-variate analysis, preoperative AAA diameter >59 mm, and AAA volume >159 cm³ were significantly associated to reintervention (P = 0.012; P = 0.002), and reintervention and death (P = 0.002; P = 0.001) during follow-up. Additionally, any increase in postoperative AAA diameter or volume was significantly associated with reintervention (P = 0.001, P = 0.001) and reintervention and death (P = 0.006, P = 0.001). Endoleak-related reintervention were also significantly associated with all of the analysed morphological parameters (P = 0.019, P = 0.005, P = 0.005, and P = 0.002, respectively).

CONCLUSIONS

Patients with larger baseline AAA size and volume as well as unfavourable early remodelling of the sac are associated to worse long-term EVAR outcome.

Infrarenal Abdominal Aortic Aneurysm Endovascular Treatment: Long-term Results From a Single-Center Experience in an Unselected Patient Population

BACKGROUND

The aim of the present study was to evaluate early-, mid-, and long-term outcomes in an unselected population of patients treated for abdominal aortic aneurysms (AAAs) by endovascular aneurysm repair (EVAR) with different commercially available off-the-shelf devices.

MATERIALS AND METHODS

A retrospective study was conducted on a prospectively compiled computerized database on patients presenting an infrarenal AAA treated between January 2008 and December 2015 in a high-volume Italian tertiary referral Center. Demographic, clinical, and specific morphological features were considered as potentially influencing the outcomes and the type of the implanted device. Outcome measures were procedure-related reintervention, AAA-related, and all-cause mortality rates at 30-day, 12-month, and long-term follow-up. Reinterventions considered for the analysis were AAA rupture, graft infection, type I or III endoleaks, type II endoleaks with sac enlargement > 5 mm, graft stenosis or occlusions, procedures related to renal or visceral ischemia, and reintervention for access vessel injury.

RESULTS

Of 498 EVAR procedures performed for elective infrarenal AAA treatment during the entire study period, 479 patients were enrolled, the mean age was 73.5 ± 7.34 years (range 51-91), and 416 (86.84%) were men. The mean maximum AAA diameter was 52.02 ± 8.04 mm (range 39-90.2), a maximum AAA diameter ≥59 mm was recorded in 107 patients (22.33%), and an aortic neck length was <10 mm in 137 (28.60%). Technical success was achieved in all patients. At a mean follow-up of 52.97 ± 26.16 months (range 1-120), overall reintervention and death rates were 8.14% and 20.04%, respectively, without AAA-related deaths. At univariate analysis, hypertension was the only demographical variable found to be associated with higher risk of reintervention, P = 0.04 (OR: 2.34; CI 95%: 1.00-5.42). Furthermore, male sex (P = 0.02; OR: 2.62; CI 95%: 1.09-6.27) and chronic renal insufficiency (P = 0.003; OR: 2.08; CI 95%: 1.27-3.42) were associated with higher mortality rates. AAA diameter ≥59 mm was statistically associated with a higher rate of both reintervention and mortality: P < 0.001 (OR: 9.05; CI 95%: 4.52-18.11) and <0.001 (4.00; 2.46-6.49), respectively.

CONCLUSIONS

Our experience seems to suggest that EVAR could be safely and effectively performed in an unselected patients' population, with encouraging results up to a ten-year follow-up.

Total Luminal Volume Predicts Risk after Endovascular Aneurysm Repair

OBJECTIVE

Large aneurysm diameter represents a well known predictor of late complications after endovascular aneurysm repair (EVAR). However, the role of the thrombus free lumen inside the abdominal aortic aneurysm (AAA) sac is not clear. It was hypothesised that greater luminal volume represents a relevant risk factor for late complications after EVAR.

METHODS

A retrospective cohort analysis was performed including all patients undergoing EVAR from 2005 to 2016 at a tertiary referral institution. Pre-operative AAA lumen volume was measured in centre lumen line reconstructions and patients were stratified into quartiles according to luminal volume. The primary endpoint was freedom from AAA related complications. Secondary endpoints were freedom from neck events (type 1A endoleak, migration >5 mm or any pre-emptive neck related intervention), iliac related events (type 1B endoleak or pre-emptive iliac related intervention), and overall survival.

RESULTS

Four hundred and four patients were included: 101 in the first quartile (Q1; <61 cm³). Patients with higher luminal volumes had wider, shorter, and more angulated proximal necks. There were more ruptured AAAs, more aorto-uni-iliac implanted devices and patients outside neck instructions for use in the 4th quartile. Five year freedom from AAA related complications was 79%, 66%, 58% and 56%, respectively (p = .007). At five years, freedom from neck related events was 86%, 84%, 73%, and 71%, respectively, for the four groups (p = .009), and freedom from iliac related events was 96%, 91%, 88%, and 88%, respectively (p = .335). On multivariable analysis, luminal volume was an independent predictor of late complications (Q4 vs. Q1 - hazard ratio: 1.91, 95% confidence interval 1.01-3.6, p = .046). Overall survival at five years was not affected by lumen volume (p = .75).

CONCLUSION

AAA luminal volume represents an important risk factor for AAA related complications. This information may be considered when deciding tailoring surveillance protocols after EVAR. However, larger studies are needed to validate this hypothesis.

Aortic sac enlargement after endovascular aneurysm repair: volume-related changes and the impact of intraluminal thrombus

Purpose

Abdominal aortic aneurysm (AAA) growth after endovascular aneurysm repair (EVAR) is still unpredictable. The issue of optimal frequency of computed tomography angiography for surveillance and its measurement method accuracy remain unclear. We aimed to assess the value of abdominal aneurysm sac volume measurement for detecting expansions and the association of preprocedural intraluminal thrombus (ILT) volume with aneurysm sac growth following EVAR.

Material and methods

A total of 107 patients underwent elective EVAR. Inclusion criteria provided a cohort of 39 patients. Changes of postoperative maximum aneurysm sac diameter and AAA volume were calculated. Volumetric AAA changes and demographic data of the cases with clinically irrelevant AAA diameter enlargement were evaluated. Preoperative ILT volumes were collected. ILT and AAA sac volume ratio was calculated. Statistical data analysis was performed using standard methods.

Results

The mean changes of maximum AAA diameter and volume in percentage after EVAR were –5.08 ± 8.20 mm and –13.39 ± 23.32%, respectively. A moderate positive linear correlation between those changes was found (R² = 0.731; p < 0.0001). The mean relative AAA volume increase in cases without clinically relevant diameter enlargement was 11.50 ± 8.27%. The means of ILT and AAA sac ratios were 0.59 ± 0.17 and 0.52 ± 1.8 in growing AAA sac and in stable or shrinking AAA sac groups, respectively (p = 0.308).

Conclusions

Volumetric AAA measurement may be useful as an additional method to diameter measurement after EVAR to identify clinically relevant sac growth. Preoperative volume of ILT may not significantly affect the growth rate of AAA after EVAR.

Is Abdominal Aortic Aneurysm Behavior after Endovascular Repair Associated with Aneurysm Wall Density on Computed Tomography Angiography?

Background and objectives: Abdominal aortic aneurysm (AAA) growth is unpredictable after the endovascular aneurysm repair (EVAR). Continuing aortic wall degradation and weakening due to hypoxia may have a role in post-EVAR aneurysm sac growth. We aimed to assess the association of aortic wall density on computed tomography angiography (CTA) with aneurysm growth following EVAR. Materials and Methods: A total of 78 patients were included in the study. The control group consisted of 39 randomly assigned patients without aortic pathology. Post-EVAR aneurysm sac volumes on CTA were measured twice during the follow-up period to estimate aneurysm sac behavior. A maximum AAA sac diameter, aortic wall and lumen densities in Hounsfield units (HU) on CTA were measured. A relative aortic wall density (the ratio of aortic wall to lumen densities) was calculated. A statistical data analysis was performed using standard methods. Results: An increase in the AAA sac volume was observed in 12 (30.8%) cases. Median relative aortic wall density on CTA scores in both the patient and the control group at the level of the diaphragm were similar: 0.15 (interquartile range (IQR), 0.11–0.18) and 0.16 (IQR 0.11–0.18), p = 0.5378, respectively. The median (IQR) relative aortic wall density score at the level of the maximum AAA diameter in the patient group was lower than at the level below renal arteries in the control group: 0.10 (0.07–0.12) and 0.17 (0.12–0.23), p < 0.0001, respectively. The median (IQR) relative growing AAA sac wall density score was lower than a relative stable/shrinking AAA sac wall density score: 0.09 (0.06–0.10) and 0.11 (0.09–0.13), p = 0.0096, respectively. Conclusions: A lower aortic aneurysm wall density on CTA may be associated with AAA growth after EVAR.

Type 2 Endoleak Incidence and Fate After Endovascular Aneurysms Repair in a Multicentric Series: Different Results with Different Devices?

BACKGROUND

The aim of this work is describing incidence and fate of type 2 endoleaks (T2ELs) in a multicentric cohort of patients treated by endovascular aneurysms repair using the Ovation device (Endologix) and comparing them with a group treated using the Excluder (W. L. Gore & Associates).

METHODS

This is a retrospective study conducted on 261 patients treated using the Ovation device and 203 using the Excluder. Outcomes were intraprocedural, 30-day, 12-month, and mean time follow-up T2EL incidence and related reinterventions. Patent inferior mesenteric artery (IMA), ≥3 lumbar arteries (LAs), intrasac thrombus volume, the mean diameter of common and external iliac arteries, external iliac artery stenosis (>70%), diameter ≤5 mm, iliac tortuosity ratio ≤0.5, thrombosis, and calcification were noted and considered as potentially influencing outcomes.

RESULTS

Patients of the Ovation group presented significantly more thrombosed, calcified, and tortuous iliac vessels than those in the Excluder group. No significant differences were noted in sac thrombosis, IMA, and LA patency. At completion angiography, T2EL was evident in 57 Ovation and 46 Excluder patients (P = 0.832). At 1 month, it was evident in 33 Ovation group and 28 Excluder group patients (P = 0.726). At 12-month and mean time (30.14 months) follow-up, no differences were evident between the 2 groups (P = 0.940 and 0.951, respectively). The log-rank test showed that the rate of T2EL-related reintervention was not different between the 2 groups (P = 0.46). Regarding anatomical characteristics, a statistically significant difference was not observed between patients presenting or not with T2EL (P > 0.05).

CONCLUSIONS

Data showed no significant differences in terms of T2EL incidence between the 2 study groups. None of preoperative anatomical features were found to be significantly associated with the appearance of T2EL.

Association Between Perioperative Fibrinogen Levels and the Midterm Outcome in Patients Undergoing Elective Endovascular Repair of Abdominal Aortic Aneurysms

BACKGROUND

We investigated the potential association between perioperative fibrinogen levels and outcome in patients undergoing elective endovascular abdominal aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs).

METHODS

Consecutive patients with an intact AAA undergoing elective EVAR with a specific bifurcated endograft (Endurant, Medtronic) were recruited between December 2012 and October 2016. Preoperative and 24-hr postoperative fibrinogen levels were recorded, and potential associations with outcome were tested. Primary outcome measures included endoleaks, lower limb ischemic complications, including endograft limb occlusion, and aneurysm-related reinterventions.

RESULTS

Ninety-four patients (91 male, mean age 71.8 ± 8.0 years) with an intact AAA were enrolled in the study. The technical success was 98% (2 failures: 1 type Ia endoleak on completion angiography, 1 lower limb ischemia immediately postoperatively requiring femoral endarterectomy). There was 1 death during the first 30 days due to myocardial infarction (1%). Another patient died 15 months after the procedure from cardiac causes. During the existing follow-up (mean 14.8 ± 14.3 months), 14 patients (15%) developed an endoleak (4, type Ia endoleak and 10, type II endoleak), 6 patients (6.3%) had lower limb ischemia/endograft limb occlusion, and 10 patients (10.6%) required reintervention. Compared with the preoperative values, no significant change occurred with regard to the fibrinogen levels 24 hr after procedure (mean preoperative fibrinogen 360 ± 101 mg/dl vs 24-hr postoperative fibrinogen 349 ± 105 mg/dl, P = 0.1). Neither preoperative nor 24-hr postoperative fibrinogen levels were significantly associated with the development of endoleaks, lower limb ischemia, or reinterventions. However, the difference in fibrinogen levels (baseline to 24 hr after procedure) was significantly higher in patients with endoleaks (median -65 mg/dl vs. 15 mg/dl, P = 0.04).

CONCLUSIONS

Perioperative fibrinogen levels may play a role in predicting midterm outcomes in patients undergoing elective EVAR and appears to be associated, directly or indirectly, with the development of endoleaks. Further studies are needed to investigate these findings and explore future therapeutic implications.

Endovascular Management of Abdominal Aortic Aneurysms: the Year in Review

OPINION STATEMENT

Endovascular aneurysm repair (EVAR) has become the predominant method of treatment for abdominal aortic aneurysms (AAA). The use of conscious sedation with local anesthesia and percutaneous femoral access has further decreased the morbidity of the procedure. Current devices can more effectively manage increasingly "hostile" aneurysm necks, while chimney grafts or dedicated fenestrated stent-grafts can be used for juxta-renal disease with favorable results. However, endovascular repair does present a new set of challenges, and endoleaks remain an area of concern. While there is general consensus that type I and type III endoleaks require treatment, type II endoleaks are the topic of ongoing research and debate. Development of devices and techniques to prevent and treat endoleak continues to progress. Advances in contrast-enhanced ultrasound are reducing reliance on computed tomography for post-operative monitoring. This is an important step in this population at high risk for the development of kidney failure. Despite these many innovations, further research is needed to optimize the care of patients with AAA.

The Influence of Preoperative Aneurysmal Thrombus Quantity and Distribution on the Development of Type II Endoleaks with Aneurysm Sac Enlargement After EVAR of AAA

PURPOSE

To determine the influence of preoperative aneurysmal thrombus quantity and distribution on the development of type II endoleak with aneurysm sac enlargement after endovascular aneurysm repair (EVAR).

MATERIALS AND METHODS

We retrospectively analyzed the pre- and postoperatively performed CT scans of 118 patients who had follow-up imaging for at least 1 year after EVAR available. We assessed preoperative thrombus perimeter (T Peri), diameter (T Dia), cross-sectional area (T CSA), and volume (T Vol). The preoperative thrombus distribution was classified into no thrombus, semilunar-shaped (anterior, right side, left side, posterior) thrombus, and circumferential type thrombus. The number of preoperative patent aortic side branches (ASB) was identified. Endpoint was type II endoleak with aneurysm volume (A Vol) increase of ≥5 % during follow-up.

RESULTS

During follow-up (2 years, range 1-9 years), 17 patients with type II endoleak had significant A Vol increase. Less preoperative T Peri, T Dia, T CSA, and T Vol were associated with A Vol increase. A circumferential thrombus distribution significantly protected against aneurysm enlargement (p = 0.028). The variables with the strongest significance for A Vol increase were preoperative T Vol/A Vol ratio (OR 0.95; p = 0.037) and number of patent ASB (OR 3.52; p < 0.001).

CONCLUSION

A low preoperative T Vol/A Vol ratio and a high number of patent ASB were associated with aneurysm sac enlargement after EVAR.