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Editor's Choice – Detection of Late Complications After Endovascular Abdominal Aortic Aneurysm Repair and Implications for Follow up Based on Retrospective Assessment of a Two Centre Cohort

Open ArchivePublished:March 21, 2020DOI:https://doi.org/10.1016/j.ejvs.2020.02.021

      Objective

      Endovascular aortic aneurysm repair (EVAR) is associated with the risk of late complications and mandates follow up. This retrospective study assessed post-EVAR complications in a two centre cohort. The study evaluated the rate of complications presenting with symptoms vs. those detected by imaging follow up. Additionally, the agreement between DUS and CTA in detecting complications was assessed in patients with both.

      Methods

      All EVAR patients from 1998 to 2012 in two centres were included. Complications were classified based on whether they were symptomatic or detected by imaging, as well as based on imaging detection modality (DUS or CTA). For patients who had undergone DUS and CTA within three months of each other, the kappa coefficient of agreement was assessed.

      Results

      Four hundred and fifty-four patients treated by EVAR were identified. The median follow up time was 5.2 (IQR 2.8–7.6) years. One hundred and eighteen patients (26%) developed 176 complications. One hundred and six (60.2%) of the complications were asymptomatic, and 70 (39.8%) were symptomatic. Two hundred and fifty-three patients had imaging with both modalities within three months of each other; the kappa coefficient for agreement between CTA and DUS for detecting clinically significant complications was 0.91. Regarding CTA as the standard modality, DUS had a sensitivity of 88.8% (95% CI 77.3–95.8%) and a specificity of 99.4% (95% CI 97.1–99.9%). Three of the complications missed by DUS were related to loss of proximal and distal seal, all occurring in patients with short sealing length on first post-operative CT scan.

      Conclusion

      Approximately a quarter of the patients developed complications, the majority of which were asymptomatic, underlining the importance of adequate surveillance. There was good agreement between CTA and DUS in detecting complications. Clinically significant complications related to inadequate seal were missed by DUS, suggesting that CTA still plays an important role in EVAR surveillance.

      Keywords

      This study assessed the occurrence of complications after endovascular aortic repair of infrarenal abdominal aortic aneurysms in a two centre cohort of 454 patients with a median follow up of 5.2 years. One quarter of the patients developed some kind of complication. In contrast to previous studies, the majority of complications were asymptomatic and detected by imaging. The study also found good agreement between duplex ultrasound without contrast (DUS) and computed tomographic angiography (CTA) in detecting clinically significant complications; however, those related to inadequate seal were missed with DUS, suggesting that CTA has an important role in EVAR surveillance.

      Introduction

      Endovascular aortic aneurysm repair (EVAR) is the primary technique for treatment of abdominal aortic aneurysms in most countries.
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      Compared with open aneurysm repair, EVAR is minimally invasive, requires a shorter hospital stay and results in less blood loss as well as faster recovery.
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      Initial experience with endovascular aneurysm repair: comparison of early results with outcome of conventional open repair.
      Additionally, EVAR has a significant short term survival benefit compared with open repair.
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      Endovascular repair versus open repair of ruptured abdominal aortic aneurysms: a multicenter randomized controlled trial.
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      Long-term outcome of open or endovascular repair of abdominal aortic aneurysm.
      On the other hand EVAR is associated with a non-negligible risk of endograft failure and rupture over time,
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      Systematic review and meta-analysis of the early and late outcomes of open and endovascular repair of abdominal aortic aneurysm.
      which mandates continuous surveillance and timely selective re-intervention. The five year re-intervention rate after EVAR has been reported to be between 16% and 33%.
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      Long-term outcomes of abdominal aortic aneurysm in the medicare population.
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      • Bown M.J.
      • Sayers R.D.
      Systematic review and meta-analysis of the early and late outcomes of open and endovascular repair of abdominal aortic aneurysm.
      As new technology and devices are introduced, new modes of endograft technical failure may occur, which mandates more rigorous follow up under such circumstances.
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      Textile aging characterization on new generations of explanted commercial endoprostheses: a preliminary study.
      ,
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      • et al.
      Editor's choice – European society for vascular surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.
      There is no consensus on EVAR surveillance, either regarding timing or imaging modality.
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      • Loftus I.M.
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      • et al.
      Heterogeneity in surveillance after endovascular aneurysm repair in the UK.
      CTA is often regarded as the gold standard for EVAR surveillance and detection of post-EVAR complications, but is associated with a risk of harm from ionising radiation and contrast exposure.
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      Is it time to eliminate CT after EVAR as routine follow up?.
      The North American aortic guidelines recommend annual imaging with DUS or CTA as a minimum for all patients.
      • Chaikof E.L.
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      • Mansour M.A.
      • et al.
      The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm.
      The new European guidelines recommend stratified follow up after EVAR based on risk of failure, with annual imaging only in patients with endoleak or short sealing zone.
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      • et al.
      Editor's choice – European society for vascular surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.
      On the other hand, reports indicate that surveillance guidelines are rarely followed in clinical practice.
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      • Baker L.C.
      • Mell M.W.
      Adherence to postoperative surveillance guidelines after endovascular aortic aneurysm repair among Medicare beneficiaries.
      Additionally, there are indications that patients undergoing surveillance have a higher mortality than those who do not comply with surveillance,
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      • Buth J.
      What determines and are the consequences of surveillance intensity after endovascular abdominal aortic aneurysm repair?.
      questioning its benefit. Karthikesalingam et al. suggested that most post-EVAR complications present with symptoms, indicating that regular imaging surveillance was futile.
      • Karthikesalingam A.
      • Holt P.J.E.
      • Hinchliffe R.J.
      • Nordon I.M.
      • Loftus I.M.
      • Thompson M.M.
      Risk of reintervention after endovascular aortic aneurysm repair.
      In this study, the occurrence of post-EVAR complications was assessed in a two centre cohort of patients treated by standard EVAR procedures over 15 years. The aim of the current report was to identify how post-EVAR complications were detected, as well as to assess their timing and frequency. It was hypothesised that most post-EVAR complications present with symptoms or would be detectable with DUS.

      Methods

      The study involved two Swedish institutions (Uppsala University Hospital, Uppsala, and Gävle Hospital, Gävle). Standard STROBE guidelines for observational studies were followed. The study complies with the Helsinki declaration and local ethical committee guidelines.

      Study design

      A study specific database was established retrospectively for all patients that had EVAR between January 1998 and December 2012 at the two centres. Patients were identified from the prospective Swedish vascular registry (Swedvasc), and local surgical registries at each centre.
      To confirm similarity between the patient cohorts of the two centres, rates of clinically significant complications, re-interventions, imaging detecting complications, rupture and aneurysm related mortality were analysed for patients surviving the early post-operative period at each centre. No significant differences were found (Table S1).
      The inclusion criteria were presence of infrarenal aortic or aorto-iliac aneurysm (elective, symptomatic and ruptured) treated by standard EVAR. Exclusion criteria included patients with isolated iliac aneurysms, patients operated with chimney, fenestrated, branched or thoracic endografts and patients with previous abdominal aortic surgery.
      Last follow up was registered in October 2016. The two centres performed 45% of aortic repairs by EVAR in 2012, based on registration in the Swedish vascular register. Data were collected including patient baseline characteristics, comorbidities, anatomy, EVAR procedures, post-EVAR follow up and outcome.
      Comorbidities included hypertension, peripheral artery diseases, cardiac diseases, diabetes mellites, known renal failure or renal insufficiency with creatinine >110 mmol/L, cerebrovascular diseases and obstructive pulmonary diseases. Anatomical parameters included maximum aortic diameter, neck length, neck diameter at 0, 5, 10, 15 mm and at the start of the aneurysm, α and β angles, iliac landing diameter and length on both sides assessed on pre-operative CTA. Procedural characteristics included endograft model and configuration and intra-operative complications. Follow up data included all surveillance imaging, complications, re-interventions and deaths.
      Suspected complications on follow up imaging that could not be verified by further diagnostic examinations were regarded as false positive and were not included in analyses. Survival data were based on cross matching with the population registry using the Swedish unique personal identification number, resulting in 100% accurate survival follow up.
      Pre-operative CTA examinations were analysed by a vascular surgeon or a radiologist at each centre (HB in Uppsala and OH in Gävle). Anatomical measurements were performed with central luminal line reconstructions using dedicated software (3mensio Vascular™, Pie medical imaging B.V., Bilthoven, the Netherlands and Acquarius iNtuition™, Terarecon, Foster City, CA, USA). Assessment of whether the procedures were performed within the endograft's instructions for use (IFU) was based on pre-operative CTA, including assessment of aortic neck (diameter, length, α and β angulation), iliac diameters and presence of iliac stenosis.
      Over many years the two units had a routine of dual imaging with both CTA and DUS as a standard to follow up EVAR procedures. All dual imaging modalities within three months of each other were used to compare the accuracy of these two modalities in detecting post-EVAR complications.
      As the study extended over a long period, the five year complication and re-intervention rate was compared for two periods (patients operated on between 1998–2005 vs. those between 2006-2012) to assess any changes in the outcome as a result of technical and surgical developments.

      Definitions

      Clinically significant post-EVAR complications were defined based on definitions of clinical failure in the reporting standards for EVAR
      • Chaikof E.L.
      • Blankensteijn J.D.
      • Harris P.L.
      • White G.H.
      • Zarins C.K.
      • Bernhard V.M.
      • et al.
      Reporting standards for endovascular aortic aneurysm repair.
      as; endograft migration ≥10 mm, aneurysm rupture, type I or III endoleak, undefined endoleak, sac expansion ≥5 mm in the presence of type II endoleak or without any clear endoleaks, graft limb thrombosis and endograft infection. Type II endoleak without sac expansion was not regarded as a clinically significant complication and thus was not assessed in this report. Clinically significant re-interventions were defined as any intervention to manage or prevent the above mentioned complications. Non-compliance was defined as no follow up imaging within the first six months of the operation, or for two consecutive years during follow up.
      • AbuRahma A.F.
      • Yacoub M.
      • Hass S.M.
      • AbuRahma J.
      • Mousa A.Y.
      • Dean L.S.
      • et al.
      Compliance of postendovascular aortic aneurysm repair imaging surveillance.
      Aneurysm related mortality was defined as death resulting from aneurysm rupture or any complication within 30 days of the operation.

      Surveillance programmes

      Post-operative surveillance was somewhat different between the two centres. In Uppsala it comprised a DUS one month post-operatively, CTA at six months, DUS at 12 months, and then, alternately, CTA and DUS annually. In Gävle the follow up programme comprised a CTA at one, six, and 12 months, and annually thereafter. In Uppsala the DUS was done by experienced sonographers, while in Gävle it was done by radiologists who subspecialised in DUS. Imaging modalities changed during the course of the study, DUS replaced CTA examinations in several patients in both centres. The rate of DUS examinations for follow up increased slightly during the study period (from 42% of follow up examinations in the period 2004–2006 to 50% in 2010–2012).

      Statistical analysis

      Analyses were performed using IBM SPSS version 23 software (IBM Inc., Chicago, II, USA). Data were assessed for normality with histogram. Missing values were handled by case deletion in each specific analysis. No adjustment for multiple testing was performed. Continuous data were presented as mean (standard deviation) and compared using Student t test if normally distributed, otherwise as median (range or interquartile range) and compared with Mann–Whitney test. Categorical data were presented as count (proportion) and compared using chi square or Fisher's exact test. A p value of < .05 was considered significant. The κ coefficient was used to evaluate agreement between the two imaging modalities used during follow up. The sensitivity, specificity and negative predictive values of the DUS were evaluated with CTA regarded as the standard method and were presented with 95% confidence interval. The outcome of early and late periods of the study was compared using Kaplan–Meier analysis and log rank test.

      Results

      A total of 454 (80.8% men) patients were treated by EVAR in the two participating institutions during the study period (Fig. 1). The mean pre-operative aneurysm diameter was 63.6 mm (SD, standard deviation 13). The mean pre-operative aneurysm diameter was 64.2 mm for men (SD 12.9 mm) and 60.4 mm for women (SD 13 mm). Fifteen patients died within 30 days after the operation and were excluded from further analyses. The median follow up was 5.2 (interquartile range, IQR 2.8–7.6) years. Of the 439 remaining patients, 118 (26.8%) developed 176 complications, 42 (9.5%) patients developed more than one complication. Of all complications, 69 (39.4%) occurred during the first post-EVAR year, 45 (25.6%) during years 2–3, and 35 (19.9%) during years 4–5. There were no significant differences in age, indication for operation, proportion treated within IFU, pre-operative aneurysm diameter overall survival and type of endograft used, between patients with vs. patients without complications (Table 1 and Fig. 2).
      Figure 1
      Figure 1Flow chart of all patients and occurrence of complications after endovascular aortic aneurysm repair (EVAR) in the two centres (Uppsala and Gävle).
      Table 1Baseline characteristics of patients with and without complications after endovascular aortic aneurysm repair (EVAR)
      CharacteristicsNo complication group (n = 321)Complication group (n = 118)p
      Male patients268 (83.5)99 (83.9).91
      Median follow up time (IQR) – years6.1 (3.8–7.9)5.1 (2.8–7.7).046
      Maximum aortic diameter ± SD – mm63.6±12.764.9±14.8.11
      Mean age ± SD – years75.1±7.074.9±6.7.71
      Rupture19 (5.9)11 (9.3).21
      Cardiac disease156 (49.8)57 (48.7).83
      Pulmonary disease59 (18.8)23 (20.0).78
      Renal disease31 (9.9)14 (11.9).54
      CVD42 (13.5)13 (11.2).52
      Outside IFU89/273 (32.6)43/104 (41.3).11
      Type of stent graft used
       Endurant72 (23.1)27 (22.5).89
       Zenith132 (42.3)53 (44.2).72
       Excluder83 (26.6)33 (27.5).85
       Talent17 (5.4)4 (3.3).36
       Other endografts8 (2.6)3 (2.5)1.0
      Data presented as n (%) unless stated otherwise. IOR = interquartile range; SD = standard deviation; CVD = cerebrovascular disease; IFU = instruction for use.
      Figure 2
      Figure 2Cumulative Kaplan–Meier estimate of survival (A) for all patients and (B) for patients with vs. without complications after endovascular aortic aneurysm repair (EVAR). Note that deaths within 30 days are excluded from this survival analysis.
      A Kaplan–Meier analysis comparing patients treated during two time periods (1998–2005 vs. 2006–2012), did not demonstrate any significant difference in the complication rate (26% vs. 26%, log rank p = .65) or re-intervention rate (25% vs. 24%, log rank p = .55) at five year follow up.
      Fig. 3 illustrates time to event for each major group of complications. Approximately half of the graft limb thromboses and types I and III endoleaks occurred within first post-EVAR year, while expansion as a result of type II endoleak or without a clear endoleak, and post-implantation ruptures occurred more evenly spread out during follow up.
      Figure 3
      Figure 3Illustration of time to event for each type of complication after endovascular aortic aneurysm repair (EVAR). The graph indicates that almost 50% of the graft thromboses and type I and III endoleaks occur during the first year after EVAR, while occurrence of aneurysm expansion and rupture are more evenly distributed over time.

      Asymptomatic complications

      One hundred and six (60.2%) of the complications were detected by surveillance imaging, of which 82 (77.3%) resulted in a re-intervention (Table 2). Forty-six (43.3%) were detected by CTA alone, and eight (7.5%) by DUS alone. Fifty (47.1%) complications had dual imaging by CTA and DUS (within three months of each other). Of the remaining two complications, one graft migration was detected by plain abdominal Xray and one type Ia endoleak was detected intra-operatively, and managed successfully 35 days later.
      Table 2Characteristics of asymptomatic imaging detected and symptomatic complications after endovascular aneurysm repair (EVAR)
      CharacteristicsAsymptomatic imaging detected complications (n = 106)Symptomatic complications (n = 70)pProportion asymptomatic imaging detected (95% CI)
      Mean time to complication ± SD – months28.6±28.531.1±30.57
      Mean time to re-intervention ± SD – months32.2±29.330.8±29.5.77
      Mean follow up time ± SD – years5.4±2.85.5±3.2.94
      Mortality during follow up41 (61.6)35 (75.6).1253.9 (42.8–64.6)
      Type of complication
       Graft migration2 (1.9)1 (1.4)1.066.7 (20.7–93.8)
       Graft limb thrombosis7 (6.6)26 (37.1)<.00121.1 (10.6–37.7)
       Post implantation rupture0 (0)17 (24.3)<.0010 (0–16.8)
       Type Ia endoleak33 (31.1)9 (12.9).00578.6 (64.0–88.2)
       Type Ib endoleak17 (16.0)3 (4.3).01685.0 (63.9–94.7)
       Type III endoleak6 (5.7)2 (2.9).4875.0 (40.9–92.8)
       Type II with expansion28 (26.4)0 (0)<.001100 (87.0–100)
       Undefined endoleak2 (1.9)1 (1.4)1.066.6 (20.7–93.8)
       Expansion without clear endoleak11 (10.4)3 (4.3).1478.6 (52.4–92.4)
       Graft infection0 (0)8 (11.4)<.0010.0 (0–35.4)
      Type of re-intervention
       Relining3 (3.7)2 (3.2)1.060.0 (23.0–88.2)
       Thrombolysis0 (0)20 (32.3)<.0010.0 (0–16.1)
       Cuff/Palmaz28 (34.6)13 (21.0).08368.3 (53.0–80.4)
       Iliac re-interventions18 (22.0)10 (16.1).3864.3 (45.8–79.3)
       Conversion to open repair2 (2.4)8 (12.9).02020.0 (5.6–50.9)
       Conversion to AUI0 (0)1 (1.6).430.0 (0–79.3)
       Coil or glue embolisation∗24 (29.3)2 (3.2)<.00192.3 (75.0–97.7)
       Other surgical or endovascular re-interventions7 (8.5)6 (9.7).8353.8 (29.1–76.8)
      Data presented as n (%) unless stated otherwise. AUI = aorto-uni-iliac configuration; CI = confidence interval; SD = standard deviation.
      ∗ Includes two patients with open ligation of lumbar arteries.

      Symptomatic complications

      Seventy (39.8%) complications were symptomatic, of which 62 (88.5%) were reintervened upon, (Table 2). Eight patients did not undergo re-interventions. Three patients had graft infection and were treated conservatively with antibiotics. One patient with symptomatic type Ia endoleak died (cancer) before re-intervention. Four patients who presented with post-implantation rupture were beyond rescue on arrival at the hospital.

      Post-EVAR rupture

      Sixteen patients presented with post-implantation rupture. The median time to rupture was 3.8 (range 0.5–10.6) years. The details of these patients are presented in Table S2. The thirty day mortality for the whole rupture subgroup was 7/16 (44%), and for those who underwent re-intervention 3/12 (25%). Median survival time (excluding 30 day mortality) after post-EVAR rupture was 4.9 (range 0.8–5.6) years.
      Eleven patients had imaging follow up within 12 months before rupture, and two patients had re-interventions within one and six months prior to rupture. No significant abnormalities could be found in seven patients before rupture. In the other four there had been three cases of expansion and one type III endoleak. The patient with type III endoleak and two other patients with sac expansion (10 respective 19 mm) ruptured less than one month from the follow up imaging. One patient had a type Ia endoleak that had been misinterpreted previously as type II and ruptured while waiting for planned imaging.
      The majority of the post-implantation ruptures (8/12) were managed successfully by an endovascular approach.

      Graft infections

      Eight patients developed graft infection; three were treated conservatively with antibiotics, one with antibiotics and abscess drainage and four with extirpation of the graft. The median time to graft infection was 1.3 (range 0.1–6) years. The median survival after graft infection was 3.7 (range 0.1–5.9) years.
      Three of these patients died as a certain consequence of the graft infection (two of those operated on by graft extirpation).

      Type II and type II with expansion

      During follow up, 78 type II endoleaks were detected, 28 of which resulted in expansion. Two post-implantation ruptures were caused by type II endoleak with expansion. One was treated by conversion to open operation, and the patient died on the third post-operative day. The second rupture was managed by open ligation of lumbar arteries and died three years later.

      Agreement between CTA and DUS

      Fifty imaging detected and four symptomatic complications had dual imaging within three months of the complication. Additionally, 198 paired images were negative or had false positive findings during follow up. The κ coefficient between CTA and DUS for detecting clinically significant complications was 0.91, indicating good agreement between the two modalities. In one case DUS showed expansion without clear leak, while CTA two months previously showed no significant expansion or endoleak. DUS could not detect four complications visualised by CTA; two type Ia, one type Ib, and one type II endoleak with expansion (Table 3). A subgroup analysis of these patients revealed that all three patients with type I endoleaks had short sealing on the first post-operative CTA.
      Table 3Agreement between computed tomography angiography (CTA) and ultrasound in detecting asymptomatic and symptomatic complications after endovascular aortic aneurysm repair (EVAR)
      Type of complicationAgreementNo agreement
      Type I26 (86.6)4 (13.3)
      Type III2 (100)0
      Expansion without clear endoleak4 (80)1 (20)
      Type II with expansion14 (93.3)1 (6.7)
      Graft limb thrombosis2 (100)0
      Data presented as n (%).
      Regarding CTA as the standard imaging modality, DUS had a sensitivity of 88.8% (95% CI 77.3–95.8%), specificity of 99.4% (95% CI 97.1–99.9%) and negative predictive value of 97.0% (87.1–99.7%).

      Compliance with EVAR follow up

      The compliance rate with imaging follow up in the study cohort was 59.2%. Fig. 4 demonstrates the proportion of attendance for post-operative follow up at the first six months and yearly thereafter. Compliant patients had higher renal and cerebrovascular comorbidity rates. There were no significant differences between compliant and non-compliant patients in the rate of complications, re-interventions or aneurysm related death (Table 4).
      Figure 4
      Figure 4The yearly proportion of patients attending post-operative follow up after endovascular aortic aneurysm repair (EVAR).
      Table 4Complications, re-interventions and mortality differences between patients compliant and non-compliant with follow up after endovascular aortic aneurysm repair (EVAR)
      CharacteristicsCompliant

      n = 229
      Non-compliant

      n = 158
      p
      Male patients195 (85.2)127 (80.4).21
      Mean age ± SD – years75.5±6.374.8±7.5.33
      Maximum aortic diameter ± SD – mm63.3±11.963.0±14.4.84
      Cardiac diseases116 (51.3)76 (48.7).61
      Pulmonary diseases46 (20.5)24 (15.4).20
      Renal failure29 (12.9)9 (5.7).021
      Cerebrovascular disease37 (16.6)13 (8.2).017
      Any complication61 (26.6)45 (28.4).68
      Imaging detected complications27 (60.0)41 (67.2).44
      Any re-intervention51 (23.4)36 (24.7).78
      Rupture9 (3.9)5 (3.1).69
      Aneurysm related morality7 (3.1)4 (2.5).76
      Data presented as n (%) unless stated otherwise. SD = standard deviation.

      Discussion

      In this two centre cohort retrospective study of consecutive patients undergoing EVAR over a 15 year period, one quarter of the patients experienced a post-EVAR complication. The majority of these complications were imaging detected and prompted re-interventions. Additionally, there was good agreement between CTA and DUS for detection of post-EVAR complications.
      The rate of complications and re-interventions after EVAR in the two centres involved in this study were comparable to the rate of complications presented by other reports.
      • De Bruin J.L.
      • Baas A.F.
      • Buth J.
      • Prinssen M.
      • Verhoeven E.L.G.
      • Cuypers P.W.M.
      • et al.
      Long-term outcome of open or endovascular repair of abdominal aortic aneurysm.
      ,
      • Nordon I.M.
      • Karthikesalingam A.
      • Hinchliffe R.J.
      • Holt P.J.
      • Loftus I.M.
      • Thompson M.M.
      Secondary interventions following endovascular aneurysm repair (EVAR) and the enduring value of graft surveillance.
      A meta-analysis of existing randomised trials
      • Stather P.W.
      • Sidloff D.
      • Dattani N.
      • Choke E.
      • Bown M.J.
      • Sayers R.D.
      Systematic review and meta-analysis of the early and late outcomes of open and endovascular repair of abdominal aortic aneurysm.
      indicates a re-intervention rate of 16–33% and rupture rate of 1–4% at five years mean follow up. In the current cohort, 80% of the complications occurred within the first five years after EVAR, and approximately half of them within the first year. The OVER trial reported that most complications and re-interventions occur within four years from EVAR and mainly within the first two years.
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      • et al.
      Open versus endovascular repair of abdominal aortic aneurysm.
      Contrary to other studies in this field, the majority of the complications in this cohort were imaging detected.
      • Karthikesalingam A.
      • Holt P.J.E.
      • Hinchliffe R.J.
      • Nordon I.M.
      • Loftus I.M.
      • Thompson M.M.
      Risk of reintervention after endovascular aortic aneurysm repair.
      ,
      • Black S.A.
      • Carrell T.W.G.
      • Bell R.E.
      • Waltham M.
      • Reidy J.
      • Taylor P.R.
      Long-term surveillance with computed tomography after endovascular aneurysm repair may not be justified.
      Detecting complications and managing them had presumably prevented many clinical complications, and this emphasises the importance of continuous follow up. On the other hand, surveillance did not prevent symptomatic complications (40%). This is an indication of the failure of the surveillance in its current form in these patients. Findings of other risk factors such as short sealing in the first post-operative CTA may help in the identification of the patients at risk of complications and may help in surveillance programme tailoring based on the individual patient's risk factors.
      • Baderkhan H.
      • Haller O.
      • Wanhainen A.
      • Björck M.
      • Mani K.
      Follow up after endovascular aortic aneurysm repair can be stratified based on first postoperative imaging.
      The compliance with follow up was approximately 60%. Although a significant proportion of patients did not comply with follow up in the current study, a 60% compliance rate is relatively high in comparison to previous reports, and may explain some of the difference in proportions of imaging detected complications between the present study and others, which reported compliance as low as 43%.
      • Garg T.
      • Baker L.C.
      • Mell M.W.
      Adherence to postoperative surveillance guidelines after endovascular aortic aneurysm repair among Medicare beneficiaries.
      ,
      • AbuRahma A.F.
      • Yacoub M.
      • Hass S.M.
      • AbuRahma J.
      • Mousa A.Y.
      • Dean L.S.
      • et al.
      Compliance of postendovascular aortic aneurysm repair imaging surveillance.
      The study does not reveal any significant differences between compliant and non-compliant patients in the rate of complications, re-interventions or aneurysm related mortality. Lack of difference in complication and re-intervention rates questions the need for intensive surveillance programmes and warrants further studies.
      The patients in this study were followed up in a dedicated vascular laboratory with experienced sonographers or radiologists subspecialising in ultrasound examination. Quality control is essential to ensure appropriate DUS follow up, and the results of the analysis of DUS outcome should be interpreted in this context. The dual follow ups in this cohort resulted in an opportunity to compare the result of follow up with DUS and CTA. The agreement between the two modalities in this study was good. The result supports the use of DUS as the main modality for EVAR surveillance, especially when considering the high negative predictive value for DUS. Other studies also support the use of DUS as a sole modality for follow up, especially after the first year when there are no signs of endoleak or expansion.
      • Chaer R.A.
      • Gushchin A.
      • Rhee R.
      • Marone L.
      • Cho J.S.
      • Leers S.
      • et al.
      Duplex ultrasound as the sole long-term surveillance method post-endovascular aneurysm repair: a safe alternative for stable aneurysms.
      • Manning B.J.
      • O'Neill S.M.
      • Haider S.N.
      • Colgan M.P.
      • Madhavan P.
      • Moore D.J.
      Duplex ultrasound in aneurysm surveillance following endovascular aneurysm repair: a comparison with computed tomography aortography.
      • Uthoff H.
      • Peña C.
      • Katzen B.T.
      • Gandhi R.
      • West J.
      • Benenati J.F.
      • et al.
      Current clinical practice in postoperative endovascular aneurysm repair imaging surveillance.
      • Collins J.T.
      • Boros M.J.
      • Combs K.
      Ultrasound surveillance of endovascular aneurysm repair: a safe modality versus computed tomography.
      A meta-analysis by Mirza et al. reported a pooled sensitivity of DUS of 74% and a pooled specificity of 94%, comparable to the results of this study.
      • Mirza T.A.
      • Karthikesalingam A.
      • Jackson D.
      • Walsh S.R.
      • Holt P.J.
      • Hayes P.D.
      • et al.
      Duplex ultrasound and contrast-enhanced ultrasound versus computed tomography for the detection of endoleak after EVAR: systematic review and bivariate meta-analysis.
      On the other hand, DUS failed to identify three serious endoleaks in this cohort. All of them had a short sealing zone on the first post-operative CTA, indicating for a risk of EVAR failure. This underlines the importance of the first post-operative CTA in predicting EVAR outcome.
      • Baderkhan H.
      • Haller O.
      • Wanhainen A.
      • Björck M.
      • Mani K.
      Follow up after endovascular aortic aneurysm repair can be stratified based on first postoperative imaging.
      Over the long time period of the study there has been a substantial evolution in endograft design and experience. In the current cohort, there was no significant difference in the five year frequency of complications after EVAR when comparing two halves of the study period (26% vs. 26%). This could be the result of a type II error. The studies by Al-Jubouri et al. and Klompenhouwer et al. both suggested that current endografts require fewer re-interventions compared with older ones.
      • Al-Jubouri M.
      • Comerota A.J.
      • Thakur S.
      • Aziz F.
      • Wanjiku S.
      • Paolini D.
      • et al.
      Reintervention after EVAR and open surgical repair of AAA: a 15-year experience.
      ,
      • Klompenhouwer E.G.
      • Helleman J.N.
      • Geenen G.P.J.
      • Ho G.H.
      • Vos L.D.
      • Van Der Laan L.
      Reinterventions following endovascular abdominal aortic aneurysm repair: the learning curve of time.

      Limitations

      The main limitation of the present study is its retrospective design with the potential for selection bias, and risk of residual confounders. The identification of cases was based on the Swedvasc and local surgical registries. The Swedvasc registry has been extensively validated, ensuring that almost all aortic cases are captured reducing the risk of selective case inclusion. Additionally, the cross matching of the patient data to the population registry ensures adequate survival follow up. However, approximately 40% of patients were non-compliant with imaging follow up, which may affect the proportion of the imaging detected complications and should be regarded as a limitation of the study. The lack of blinding during evaluation of imaging examinations is another limitation. A total of 250 dual examinations was used to compare CTA and DUS, and κ coefficient showed good agreement between the two modalities. However, it is important to underline that the evaluators of one imaging modality were not systematically blinded to the outcome of the second modality. The fact that operators were not always blind to the result of the first imaging limits the robustness of this conclusion.

      Conclusion

      In this retrospective consecutive cohort study, a quarter of patients developed post-EVAR complications during a median follow up of five years, including a 1% yearly rupture risk. In contrast to previous reports, the majority of these complications were imaging detected. A high proportion of the complications occurred during the first year after EVAR, indicating the importance of adequate early imaging. There was good agreement between CTA and DUS in detection of clinically significant complications. Although the sensitivity of DUS in detecting complications was 88.8%, clinically significant complications were missed by DUS, specifically in patients with inadequate sealing measured on the first post-operative CTA.

      Conflict of Interest

      None.

      Funding

      None.

      Appendix A. Supplementary data

      The following is the Supplementary data to this article:

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      Linked Article

      • Surveillance Imaging After Endovascular Abdominal Aortic Aneurysm Repair: A Necessary Enigma!
        European Journal of Vascular and Endovascular SurgeryVol. 60Issue 2
        • Preview
          The study by Baderkhan et al.1 is a retrospective analysis of prospectively recorded data of patients having had endovascular abdominal aortic aneurysm repair (EVAR) between 1998 and 2012 at two Swedish centres. The authors reached two conclusions after analysing the cohorts compliant and not compliant with a post-EVAR surveillance protocol. The compliant protocol required early post-EVAR computed tomographic angiography (CTA) imaging and annual follow up imaging with CTA and/or duplex ultrasound (DUS).
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