|
Mertens, j., houthoofd, s., daenens, k., fourneau, i., maleux, g., lerut, p., & nevelsteen, a.(2011).Long-term results after endovascular abdominal aortic aneurysm repair using the cook zenith endograft.Journal of vascular surgery, 54(1).Https://doi.Org/10.1016/j.Jvs.2010.12.068.Objective: this study assessed the long-term outcome of patients with abdominal aortic and aortoiliac aneurysms treated with the cook zenith endovascular graft (cook inc, bloomington, ind).Methods: between september 1998 and october 2003, 143 patients underwent elective endovascular aneurysm repair (evar) using the cook zenith endograft.Data from these patients were reviewed from a prospective database in october 2008.Primary outcome measures were overall survival, intervention-free survival, and freedom from aneurysm rupture.Secondary outcome measures were early and late postoperative complications, including endoleaks.Results: mean follow-up was 66.4 months (range, 1.9-121.0 months).Overall survival was 72.1% at the 5-year follow-up and 50.9% at the 8-year follow-up.Intervention-free survival was 77.1% at 5 years and 63.8% at 8 years.There were no reintervention-related deaths.Six patients had a late aneurysm rupture, which was fatal in three.Freedom from aneurysm rupture was 98.1% at 5 years and 91.0% at 8 years.Late complications occurred throughout the follow-up period, with a tendency for aneurysm rupture and surgical conversion to occur at a later stage in the follow-up period.Aneurysm sac enlargement during follow-up was associated with late aneurysm rupture and with the need for reintervention.Conclusion: elective evar using the cook zenith endograft provides excellent results through a mean follow-up of >5 years.There is a low aneurysm-related mortality and an acceptable rate of postoperative complications and reinterventions.The occurrence of late complications throughout the follow-up period stresses the need for continued postoperative surveillance in evar patients.Early benefits of endovascular aneurysm repair (evar) have been published in previous reports and demonstrated in randomized controlled trials.Long-term outcome analysis of patients treated with the first generations of commercially available stent grafts has shown a considerable risk of late complications and reinterventions.Device-specific early-term to medium-term follow-up reports have shown good results for the later generation of endografts.The zenith endograft (cook inc, bloomington, ind) is a third-generation device that is widely used for evar.It is available in a custom-made two-part design (fig 1, a) and in a standard three-part design (trifab, fig 1, b).Long-term surveillance of reintervention and conversion procedures after evar is needed to provide evidence for the use of this procedure as an elective option.The aim of this report is to present our single-center results of the cook zenith endograft after a mean follow-up of 66.4 months (range, 1.9-121.0 months).Material and methods: the follow-up data of 143 patients who underwent elective evar were retrieved from a prospective database.Patient data were collected and recorded on case record forms at the time of the evar procedure according to the european collaborators on stent-graft techniques for aortic aneurysm repair (eurostar) criteria and as required by the belgian national health insurance office (riziv).All patients signed an informed consent form (as required by the riziv to receive reimbursement), approving with the proposed follow-up schedule and with the inclusion of preoperative, intraoperative, and follow-up data in a prospective database.All evar procedures were performed between september 1998 and october 2003 at the gasthuisberg university hospital in leuven, belgium, and the data were reviewed in october 2008.Inclusion and exclusion criteria for evar, as defined by the riziv, are summarized in table i (online only).Preoperative patient risk stratification was performed using the american society of anesthesiologists (asa) classification (table ii, online only) and the society for vascular surgery (svs)/international society for cardiovascular surgery (iscvs) risk scoring system (table iii, online only).As determined by risk classification derived from clinical assessment combined with asa and svs-iscvs risk scoring, 26 patients (18.2%) were considered unfit for open surgery.Preoperative imaging was performed using computed tomography (ct) scans in all patients and calibrated arteriography in selected patients.All evar procedures were performed by a member of the vascular surgery staff and an interventional radiologist, both meeting the acknowledgment criteria as defined by the belgian national health insurance office (with theoretic and practical training, as well as sufficient experience by having implanted a minimum of 20 endografts).All procedures were performed in the operating theater using a standard mobile image intensifier.General anesthesia was used in most cases, and access to the femoral arteries was obtained through surgical dissection.All patients received intravenous antibiotic prophylaxis with cefazolin (2 grams) and intravenous heparin (according to body weight) during the procedure.In the beginning of the treatment period, only the custom-made two-part design of the zenith endograft was available.The first trifab endograft was used in january 2000 and became the graft of choice.Postoperative follow-up included plain abdominal radiographs in four projections and ct scans at 3, 6, 12, 18, and 24 months, and yearly thereafter.All plain abdominal radiographs and ct scans were reviewed by a senior member of the vascular surgery staff and a senior interventional radiologist.In 16 patients, color duplex ultrasound (cdu) imaging was performed at the same intervals.In three other patients, ct scans were performed in the beginning of the follow-up period and cdu was used thereafter.All cdu procedures were performed by a senior ultrasound technician.Primary technical success was defined as successful deployment of the endograft without type i or iii endoleak, graft limb occlusion, or conversion to open surgery.Overall survival, intervention-free survival, and freedom from aneurysm rupture were analyzed as outcome parameters using the kaplan-meier method.Early postoperative mortality and early and late postoperative complications were also analyzed.Late postoperative morbidity included late postoperative complications (endoleaks, migration, graft limb-related complications, and stent fractures), reinterventions, and late conversions to open surgery.Data were analyzed using spss software (spss, chicago, ill).Continuous variables are reported as mean ± standard deviation.For variables not normally distributed, as determined by a one-sample kolmogorov-smirnov test, median and range are reported.Survival analysis was performed using the kaplan-meier method.Results: the 143 patients (134 men and nine women) in the study were a mean age of 71.3 ± 6.9 years.The mean preoperative serum creatinine level was 1.33 mg/dl (median, 1.21; range, 0.77-7.77 mg/dl).The mean aneurysm diameter was 57.5 mm ± 10.8 mm, n = 142), mean neck length was 26.8 mm (median, 24.0 mm; range, 7.0-85.0 mm; n = 122), and mean neck diameter was 24.4 ± 3.4 mm, n = 130).Thirteen patients had an aneurysm neck length <15 mm, and 14 patients had an aneurysm neck diameter >28 mm, which were outside of the zenith endograft instructions for use.Procedural results: a bifurcated device was used in 128 patients, of which 46 were treated with a two-part device, and 82 were treated with a trifab device.An aorto-uni-iliac device was used in 15 patients with standard femorofemoral crossover bypass.One of the 15 aorto-uni-iliac devices implanted was used as a conversion procedure because of the inability to advance the second limb of a bifurcated device.Before the evar, embolization of one internal iliac artery was performed in 19 patients and both internal iliac arteries were embolized in five patients.All additional procedures performed concurrently with evar are summarized in table iv.All endovascular treatments had successful procedural outcomes without type i or iii endoleaks or limb occlusions, and there were no conversions to open surgery (100% primary technical success rate).Mean operating theater time (including additional procedures) was 124.7 minutes (median, 120; range, 60-360 minutes, n = 142), mean fluoroscopy time was 28.1 minutes (median, 24.5; range, 8-102 minutes, n = 118), and the mean amount of iodine contrast medium used was 106.3 ml (median, 93.5; range, 35-417 ml; n = 114).Early postoperative mortality and morbidity.The in-hospital and early postoperative (30-day) mortality rate was 0%.Mean hospital length of stay was 4.2 days (median, 3; range 2-24 days), and mean serum creatinine level at discharge was 1.28 mg/dl (median, 1.16; range 0.71-7.35 mg/dl, n = 140).Early postoperative complications occurred in 19 patients (13.3%), with access site complications observed in 10 (7.0%; table v).Follow-up: of the 143 evar patients, 141 had follow-up data available until october 2008 or until the time of death or device explantation; in four patients, imaging data were incomplete.Mean follow-up time was 66.4 ± 31.3 months (range, 1.9-121.0 months).Late mortality and morbidity.The overall survival rate, as estimated by kaplan-meier analysis, was 93.6% ± 2.1% at 1 year, 81.5% ± 3.3% at 3 years, and 72.1% ± 3.8% at 5 years.The kaplan-meier analysis predicted the probability of survival would be about 50.9% ± 5.0% (n = 29 remaining patients at risk) at 8 years (fig 2).Sixty patients (42.0%) died during follow-up, and the causes of death are summarized in table vi.A late aneurysm rupture occurred in six patients (4.2%), resulting in three deaths (2.1% aneurysm-related mortality).These six patients had aneurysm growth =5 mm during follow-up.An underlying endoleak was identified in five patients: two with known type ii endoleaks, and one each with known type ia endoleak (no treatment because of technical and comorbidity issues), a new bilateral type ib endoleak, and a new type iii endoleak.Reinterventions for the ruptures are summarized in table vii.Late aneurysm ruptures occurred after a mean follow-up of 66 months (range, 47-90 months) and five of the six late aneurysm ruptures occurred after the 5-year follow-up (table viii).Freedom from aneurysm rupture was 100% at 1 and 3 years.The kaplan-meier estimate of freedom from aneurysm rupture was 98.1% ± 1.4% at 5 years and 91.0% ± 4.0% at 8 years (fig 3).Late postoperative complications (with or without reintervention) occurred in 57 patients (39.9%), consisting of 35 patients with one event, 14 with two events, six with three events, and two with four events (table vii).Late postoperative endoleaks occurred in 47 patients (32.9%), most of which were type ii endoleaks without clinical significance (without aneurysm sac growth) and not requiring reintervention.Type i endoleak was observed in 18 patients (12.6%).Six of the type i endoleaks were type ia (proximal fixation point in six patients) and 14 were type ib (distal fixation point in 12 patients).Four incidences of type iii endoleak were observed in three patients (2.8%) with one patient presenting with bilateral type iii endoleaks).Three of these type iii endoleaks were caused by an iliac limb disconnection, and one had an iatrogenic cause (postcatheterization).Occurrences of type i and type iii endoleaks throughout the follow-up period are summarized in table viii.Migration (>10 mm) of the device was observed in one patient (0.7%), without endoleak and did not require reintervention.Iliac limb stenosis (n = 3) or occlusion (n = 8) occurred in 11 patients (7.7%).Six of eight iliac limb occlusions occurred =3 months after the evar procedure.Stent body fractures were observed in six patients (4.2%), and disconnections between the main body graft and the bare metal top stent were observed in three (2.1%; fig 4).A type ia endoleak with aneurysm sac enlargement developed in one of the three patients with a top stent disconnection.No reintervention was performed because of technical and comorbidity issues, and the patient subsequently died after an aneurysm rupture.Most of the observed first-time complications (59.6%) occurred during the first 2 years of follow-up, but they continued to occur throughout the follow-up period (fig 5).During follow-up, 48 reinterventions were performed in 37 patients (25.9%), comprising 28 with one intervention, eight with two interventions, and one with four interventions (table vii).The kaplan-meier estimate of intervention-free survival rate was 90.7% ± 2.5% at 1 year, 83.5% ± 3.2% at 3 years, and 77.1% ± 3.8% at 5 years.The kaplan-meier analysis predicted the probability of intervention-free survival would be about 64.8% ± 5.8% (n = 19 remaining patients at risk) at 8 years (fig 6).During the first 2 years of follow-up, 48.6% of the first-time reinterventions were performed, and reinterventions continued to be performed throughout the follow-up period (fig 5).There were no deaths related to reintervention, although one patient died of cardiac causes 2 months after thrombolysis of an occluded iliac limb (complicated with bleeding).Late conversion to open surgery was performed in five patients (3.5%), and indications for endograft removal were type ia endoleak in two patients, and one patient each with persisting type ii endoleak with aneurysm sac enlargement despite embolization, type iii endoleak with aneurysm rupture (urgent reintervention and conversion), and endotension with aneurysm sac enlargement.Late conversions to open surgery occurred after a mean of 54 months (range, 32-65 months), and three of the five conversions occurred after 5 years (table viii).During further follow-up, all patients who underwent conversion had a favorable outcome without aneurysm-related complications or further reinterventions.Mean aneurysm sac diameter was 54.2 ± 11.3 mm (n = 116) at 1 year, 49.2 ± 15.7 mm (n = 98) at 3 years, and 46.2 ± 15.6 mm (n = 60) at 5 years.Aneurysm sac shrinkage (=5 mm) was observed in 89 of 143 patients (62.2%).In 59 patients, aneurysm sac shrinkage was observed at 1 year (in three of these patients, there was aneurysm sac growth at a later stage during follow-up), in 27 patients sac shrinkage was observed at 3 years, and in another three patients at 5 years.Significant increase (=5 mm) in aneurysm sac diameter was observed in 25 of the 143 patients (17.5%).Aneurysm sac growth was observed at 1 year in 18 patients, at 3 years in five patients, and at 5 years in another two patients.In 10 of 18 patients with aneurysm growth at 1 year, an endoleak was observed (two type ia, two type ib, and six type ii).In five of seven patients with aneurysm growth at the 3- or 5-year follow-up, an endoleak was observed (one type ib, three type ii, and one type iii).In three of these seven patients, aneurysm sac shrinkage (=5 mm) was observed at an earlier stage during follow-up, including one patient with a type iii endoleak and one patient with a type ii endoleak that was treated by embolization, but later this patient developed a type ia endoleak with subsequent rupture of the aneurysm.A reintervention was performed in 17 of 25 patients (68.0%) with significant aneurysm growth during follow-up.All late aneurysm ruptures also occurred in patients with an increase in aneurysm sac diameter of =5 mm.No significant differences were noted in mean preoperative aneurysm diameter, neck length, or neck diameter between patient groups with and without significant aneurysm sac enlargement (table ix).In the 13 patients with a preoperative aneurysm neck length <15 mm, two postoperative stent fractures occurred during follow-up, but there was no need for reintervention.In the 14 patients with a preoperative aneurysm neck diameter >28 mm, four late postoperative complications occurred, comprising two iliac limb stenoses, one type ib endoleak, and one type ii endoleak, with one reintervention stenting for limb stenosis and one extension for a type ib endoleak.Discussion: this report presents the long-term follow-up results (mean follow-up of 66.4 months) of our single-center experience with the use of the cook zenith endograft for the elective treatment of abdominal aortic and aortoiliac aneurysms.In other published reports of the zenith endograft, mean follow-up ranged from 7 to 26.9 months.Greenberg et al reported the 5-year results of the zenith u.S.Multicenter trial in 2008, and the uk evar trial investigators have recently published their long-term results of the evar 1 and 2 trials, which included patients treated with the zenith and other endografts.In this series, the primary technical success rate was 100%, and there was no early postoperative mortality.In previously published reports of the zenith endograft, the primary technical success rate ranged from 91% to 100%, and early postoperative (30-day) mortality ranged from 0.1% to 4.1%.Mean overall survival in this study was 72.1% at 5 years and 50.9% at 8 years.The intervention-free survival was 77.1% at 5 years and 64.8% at 8 years.During the follow-up period, five devices (3.5%) were explanted and 48 reinterventions were performed in 37 of the 143 patients (25.9%).When compared with recently published medium-term to long-term results with the zenith endograft, the survival rates are similar; however, a higher rate of late aneurysm ruptures, conversions to open surgery, and reinterventions in general was observed in this series.Possible contributing factors are the intensity of the follow-up program, the availability of nearly all patient data for follow-up, and the longer follow-up period.This retrospective analysis is not a clinical trial, and the selection of patients for evar reflects the clinical practice at the time of the treatment period (1998-2003).This creates a possible selection bias, because at that time there was a tendency to perform evar in higher-risk patients who have been shown to have a higher risk of aneurysm-related morbidity during follow-up.In a report based on the u.S.Multicenter zenith trial, greenberg et al demonstrated a 5-year intervention-free survival of 80.5% in a standard-risk patient group and 75.2% in a high-risk patient group, the latter being comparable to the 5-year intervention-free survival in our patient series.In the uk evar 1 trial patient group (51% of patients treated with the zenith endograft), there was a 54% overall survival and a 93% aneurysm-related survival at the 8-year follow-up, which is similar to the results in this patient series.For the evar 2 patient group (60% of patients treated with the zenith endograft), overall survival at 8 years was 30% and aneurysm-related survival was 86%.Most late complications and reinterventions in this patient series were observed during the first year(s) of follow-up, but throughout the follow-up period, a risk remained for patients to develop a first-time event with or without reintervention (fig 5).Reinterventions can often be performed by endovascular means with few complications.No deaths in this patient series were related to reintervention.The most serious late postoperative events and reinterventions showed a tendency to occur or be performed later in the follow-up period, with late aneurysm ruptures and conversions to open surgery occurring or being performed after a mean follow-up of 66 and 54 months, respectively.Fifty percent of type i endoleaks occurred after =5 years, and all but one (iatrogenic) type iii endoleaks occurred after =3 years.These findings stress the need for continued postoperative surveillance of evar patients.Concerns related to the use of iodinated contrast agents, cumulative radiation exposure, and the costs of ct imaging have raised interest in the development of new evar surveillance regimens.In a recently published report based on the u.S.Multicenter zenith trial and in the recently published svs practice guidelines for the care of patients with an aaa, contrast-enhanced ct imaging is recommended at the 1- and 12-month follow-up visit after evar, and ct imaging at 6 months is performed only if the 1-month examination raises concerns.If neither an endoleak nor aneurysm enlargement is documented during the first year after evar, cdu may be a reasonable alternative for ct imaging in postoperative surveillance.The role of cdu in surveillance of evar patients has also been described in other published reports.Aneurysm sac shrinkage (=5 mm) was noted in 62.2% of patients.A significant increase in aneurysm sac diameter (=5 mm) was seen in 25 patients (17.5%) and was associated with the risk of aneurysm rupture and the need for reintervention.There was no significant difference in preoperative aneurysm diameter, neck diameter, or neck length when patients with expanding sac size were compared with the rest of the patients in this series.Other published reports, however, have described predictive factors of postoperative aneurysm sac enlargement and endoleak occurrence, including preprocedure aneurysm diameter, neck thrombus, plaque or calcification, neck angulation, and patient gender.Patients in this series with short aneurysm necks or large-diameter necks outside of the zenith's instructions for use did not seem to have more complications or reinterventions.Suprarenal fixation with a bare metal top stent is one of the device-specific characteristics of the zenith endograft.As a result, the incidence of device migration is very low in all previously published results of the graft.In this series, migration was observed in one patient (0.7%), in which the migration remained unchanged during further follow-up and did not require reintervention.The interrupted stent design of the zenith device is thought to be associated with a higher risk of iliac limb kinking, stenosis, or occlusion.Iliac limb stenosis occurred in three patients (2.1%) in this series and occlusion in eight (5.6%).Most iliac limb occlusions occurred shortly after the evar procedure, which has been reported previously.Most of these complications related to the graft limb occurred in patients treated with the earlier generation of the device during the first 2 years of the treatment period.In the later stages, these iliac graft limb-related complications were prevented by more careful patient selection and the preferable use of other endografts in the treatment of patients with tortuous or narrow iliac arteries.More recently, the manufacturer has also made changes in the device and stent design of the iliac limbs (increased spacing between z-stents) to increase the compatibility with difficult iliac anatomy.Iliac limb disconnection (with type iii endoleak) was seen in two patients (1.4%, one bilateral case).One patient had a two-part endograft and the other patient (bilateral case) had a trifab endograft.Theoretically, there is a greater risk of limb disconnection in the standard trifab three-part design compared with the custom-made two-part design.Fractures in the metallic stent design were observed in six patients (4.2%) during follow-up.In five patients, these fractures occurred in the most distal stent proximal to the device's bifurcation, and there is possible concern that these fractures are associated with the occurrence of type iii endoleaks.However, this has not been published in previous reports of the zenith endograft, nor was it observed in this patient series.The manufacturer altered the endograft design in 1999, shortening the most distal body stent from 22 to 14 mm.In this patient series, four of five patients with a fracture of the most distal body stent had been implanted with grafts before the change in device design.The identification of stent fractures requires thorough review of follow-up examinations because minor stent graft changes are not always easily identified and are sometimes missed by the reviewer or the radiologist.In another three patients (2.1%), a disconnection of the bare metal top stent from the endograft main body (fig 4) was observed.In one of these patients, a type ia endoleak developed with subsequent aneurysm rupture.This complication has previously been reported in older zenith endografts and in the meantime, the manufacturer has altered the graft design, providing a more secure fixation of the bare top stent to the body of the endograft.The last reported top stent disconnection in our series occurred in an endograft placed in may 2001.Conclusion: the cook zenith endograft is a safe and durable device for the elective endovascular treatment of abdominal aortic and aortoiliac aneurysms.This patient series provides good results through a mean follow-up period of =5 years, with a low aneurysm-related mortality and an acceptable reintervention rate.Results have also improved because of increased experience with the graft, better patient selection, and improved stent graft design.Late complications occurred throughout the follow-up period, whereas late aneurysm rupture and conversion to open surgery showed a tendency to occur or be performed later in the follow-up period, stressing the need for continued follow-up in patients treated with the zenith or any other endograft.The focus of this report are the two patients who had late postoperative complications of suprarenal stent separation and migration of the main body graft.No reintervention was reported.This information can be found in table vii (late post operative complications and reinterventions) in the article.
|
