European Collaborators Research Articles

Effect of improved endograft design on outcome of endovascular aneurysm repair

Objective This study was undertaken to identify factors that lead to improvements in the results of endovascular aneurysm repair, with particular focus on new endograft design. Methods We analyzed data for patients enrolled in the European Collaborators on Stent Graft Techniques for Abdominal Aortic Aneurysm Repair (EUROSTAR) registry, and compared those for endografts now withdrawn from the market with those for endografts currently in use. Patients in whom a variety of endograft types were used in small numbers were excluded. Postoperative and long-term outcomes were initially compared with univariate analyses, and subsequently multivariate tests were used to adjust for baseline differences between the 2 groups. The main outcome measures were freedom from a variety of secondary interventions, aneurysm rupture, and death. Results Some 1224 patients received “withdrawn” endografts, and 2768 patients received “current” endografts. The 2 groups were generally similar, but patients with current devices were more often men, significantly older, more frequently unfit for open surgery, and had larger aneurysms with wider necks. Of no surprise, current endografts were also more often used by experienced (>60 previous cases) surgical teams (44% vs 20%; P < .0001). Thirty-day clinical outcomes were comparable in the 2 groups, although patients with withdrawn devices were less likely to have type II endoleak (9.2% vs 5.5%; P < .0001), and those with current devices had a shorter mean hospital stay (5.4 vs 6.8 days; P < .0001). At 3 years more patients with current devices were free from secondary transfemoral intervention (88.4% vs 76%; P < .0001) and conversion to open repair (95.4% vs 93.4%; P = .007). Aneurysm-related mortality at 3 years, defined as death due to aneurysm rupture or within 30 days of a secondary intervention, was also less frequent with current endografts (2.7% vs 4.4%; P = .02). Aneurysm rupture at 3 years was infrequent (0.8% vs 1.8%; P = .07). At multivariate analysis the use of current devices was a protective factor against late conversion to open repair (hazard ratio, 0.49; 95% confidence interval, 0.28-0.86; P = .014) and aneurysm-related death (hazard ratio, 0.51, 95% confidence interval, 0.34-0.75; P = .0008). Larger aneurysm or neck diameter and shorter neck length were also associated with late conversion to open repair; larger aneurysm diameter, older age, and unfitness for open surgery were predictive of aneurysm-related death. Conclusion Modern endograft design has improved the results of endovascular aneurysm repair.

An Update on the Important Findings from the EUROSTAR EVAR Registry

This article summarizes the important findings to emerge from the European Collaborators on Stent-Graft Techniques for Abdominal Aortic Aneurysm Repair (EUROSTAR) Registry since its inception in 1996. The Registry is an open observational study of the outcomes from endovascular aneurysm repair (EVAR). Data have been contributed, on a voluntary basis, by 135 vascular centers from 18 European countries. Patients are registered prospectively, and data analysis is on an intention-to-treat basis. Results from the first generations of endograft were characterized by excellent early results but poor durability of abdominal aortic aneurysm repair. EUROSTAR data have played a vital role in informing the technical evolution of subsequent generations of endograft and their clinical application. The latest data from EUROSTAR show significant improvements in all outcome measures, most importantly, those relating to durability. EUROSTAR has tracked and informed the evolution of EVAR. Improving results confirm that substantial progress has been made since 1996. EUROSTAR continues to contribute to this ongoing process.

Con: endovascular stent repair for aortic aneurysm surgery is not associated with lower perioperative risk

CONVENTIONAL OPEN operative repair (OR) of abdominal aortic aneurysms (AAAs) has been the gold standard beginning with the initial report in 1951 by Dubost and collaborators.1 The endoluminal approach to the management of AAA repair was reported by Parodi et al2 and Volodos et al3 in 1991 and development of endoluminal grafts has increased exponentially since then. Endoluminal or endovascular AAA repair (ER) has gained astonishing popularity. The early results of ER were extremely promising, showing a reduction in hospital stay, decrease in blood loss, and lower complication rates compared with results of standard OR.4,5 However, mortality rates of ER were not uniformly superior, and sometimes inferior to, OR.6 The opportunity for a less invasive technique to treat a potentially life-threatening disorder, permit more rapid recovery, reduce morbidity, and potentially achieve cost savings by shortened hospitalizations and decreased use of hospital resources is attractive to patients, physicians, hospital administrators, and insurers. The initial enthusiasm for ER was understandably high, although estimates of the number of patients with AAA anatomy suitable for ER varied widely. A recently designed national multicenter ER trial in Great Britain has estimated that 60% of all infrarenal AAAs are amenable to ER treatment.7 Whereas many authorities have suggested that ER could substantially lower the excessive mortality and morbidity associated with ruptured and symptomatic AAAs, Lee and colleagues8 have shown that only about 40% of such patients are eligible for ER treatment because of unfavorable anatomic features. As experience using endoluminal repair of AAAs increased, reports of adverse outcomes became progressively more frequent. For example, the EUROSTAR Project (EUROpean Collaborators on Stent/graft Techniques for Aortic Aneurysm Repair) is essentially a voluntary registry established in 1996.9 To date, nearly 100 European centers of vascular surgery have contributed data on more than 3,000 patients treated with a variety of commercially available endografts. Initially, the perioperative mortality for ER was 3.4%, and the endoleak (persistent flow within the AAA sac) rate was 15.7% after 430 patients had been entered into the database during the first year. However, at 2 years, after 895 patients had been voluntarily registered, the early endoleak rate remained essentially unchanged, but another 18% of patients had developed new endoleaks; moreover, additional problems associated with ER such as late limb occlusions were noted with increasing frequency, and reports began to appear with alarming perioperative mortality rates, as high as 11.3%.9,10 Thus, early unrealistic optimism about ER repair of AAAs has been replaced with a more pragmatic understanding of its benefits and limitations. Randomized, controlled, prospective trials (RCTs) are necessary to establish the most appropriate application of the ER technique compared with established conventional open repair, and, to date, there has been no large-scale randomized controlled trial of OR versus ER for AAAs. Predictably, as shown by many innovations in surgical approaches, there is a pendulum effect. Even the lay press has become involved. The initial media onslaught publicizing unrealistic benefits and successes of ER was closely followed by numerous backlash publications urging caution in the widespread application of ER for AAAs. A front-page story by Julie Appleby12 that appeared in the September 24, 2001 issue of the USA Today newspaper was entitled Debate Follows Development of Medical Device: Smaller Incision Cuts Recovery Time, but Durability Questioned. ER has also been assailed in the medical literature, as reflected in an editorial by Collin and Murie13 entitled Endovascular Treatment of Abdominal Aortic Aneurysms: A Failed Experiment, in which the authors opined that “the gestation period of experimental endovascular aneurysm repair has already been ten years. . .When eventually delivered, it will probably be stillborn. We believe it is dead already.”

Rupture of Infra-renal Aortic Aneurysm after Endovascular Repair: A Series from EUROSTAR Registry

Objectives. Although small, the risk of rupture after EVAR remains a major concern. The aim of this study was to identify mechanisms of late aneurysm rupture after endovascular repair. Methods. Patients who suffered a proven aneurysm rupture after EVAR were identified from the EUROSTAR (European Collaborators on Stent-graft Techniques for Abdominal Aortic Aneurysm Repair) registry. Complications preceding rupture were studied to identify common patterns and possible mechanisms of late rupture. Results. A rupture was documented in 34 patients resulting in death of 21 (62%). Adverse events documented during previous follow-up in these patients included endoleak (30%), migration (18%), limb occlusion (12%) and kinking (12%). The findings at time of rupture were documented in 24 patients and including endoleak: Type III (10), Type I (9), Type II (1); stent-graft disintegration (2) and migration (3). Aneurysm diameter changes could be ascertained in 24 patients and had increased in only seven. Conclusion. The importance of graft-related endoleak, stent-graft disintegration and migration in the causation of aneurysm rupture was confirmed. Poor compliance with follow-up schedule was also identified as a common feature. However, the absence of complications in some patients, who attended regularly for follow-up, highlights the difficulty of predicting rupture after EVAR.

C. parvum in Melbourne's catchments: investigating prevalence and developing high-resolution molecular detection tools

The Melbourne Water Corporation has funded the University of Melbourne Veterinary School to study the prevalence of Cryptosporidium and Giardia in animals in water catchment areas of Melbourne and to establish molecular tools for the identification of the parasite to the species and strain levels. In a first epidemiological survey Cryptosporidium was found in high prevalence (17 of 24 species examined; n = 490), whereas Giardia was detected in two animals. A polymerase chain reaction (PCR)-based mutation scanning technique was established for identification of C. parvum to the strain level from oocyst isolates. This so-called single strand conformation polymorphism (SSCP) technique allows high-resolution analysis of genetic variability within and between populations of C. parvum. In a blind test, SSCP genotyping of 23 DNA samples representing C. parvum from different host and geographical regions demonstrated that the method could correctly type samples identified previously using a range of other methods, and displayed higher levels of sequence variability compared with conventional approaches. Hence, the method provides a powerful epidemiological tool for diagnosis as well as for identifying the source of waterborne outbreaks. Future molecular epidemiological surveys of cryptosporidosis/Cryptosporidium will be conducted together with Australian and European collaborators, with a particular emphasis on human cryptosporidosis.

Europe ramps up its research goals

Europe ramps up its research goals

The evolving technique of endovascular stenting of abdominal aortic aneurysm; time for reappraisal.

to investigate the occurrence of intra-operative device-related complications during stent-grafting for abdominal aortic aneurysm. data on patient characteristics, vascular morphology, operative technical details, procedural and device-related complications were obtained from the European collaborators on stent-graft techniques for abdominal aortic aneurysm repair (EUROSTAR) registry. Only intra-operative device-related complications were taken into account. Potential risk factors for device-related complications were examined by logistic regression analysis. The association between these complications and conversion to open surgery and death were determined. between January 1994 and July 2000, 2862 patients in 90 participating hospitals underwent endovascular abdominal aortic aneurysm repair. Device-related complications occurred in 238 (8.3%) patients. Complications were associated with the age of the patient (p=0.002), gender (p=0.05), smoking habit (p=0.001), pre-operative aneurysm diameter (p=0.005), type of device implanted (p=0.0001), fitness of the patient for open surgery (p=0.002), and year of operation (p=0.001). Adjusted for risk factors, the occurrence of complications decreased between 1994 to 2000 from 21.7% to 7.3%, respectively. Patients with device-related complications were 13.6 times (95% CI; 9.2-20.1) more likely to have conversion to an open procedure and 2.4 times (95% CI; 1.4-4.0) more likely to die within 30 days of the operation. intra-operative device-related complications were common, although appear to be decreasing in frequency, and were significantly related to conversion and post-operative death.

Incidence and risk factors of late rupture, conversion, and death after endovascular repair of infrarenal aortic aneurysms: The EUROSTAR experience

Objective: The EUROSTAR (European Collaborators on Stent/graft techniques for aortic aneurysm repair) Registry was established in 1996 to collect data on the outcome of treatment of patients with infrarenal aortic aneurysms with endovascular repair. To date, 88 European centers of vascular surgery have contributed. The purpose of the study was to evaluate the results of this treatment in the medium term (up to 4 years) according to the analysis of “hard” or primary end points of rupture, late conversion, and death. Patients and Methods: Patients with aortic aneurysms suitable for endovascular aneurysm repair were notified to the EUROSTAR Data Registry Centre before treatment to eliminate bias due to selective reporting. The following information was collected on all patients: (1) demographic details and the anatomic characteristics of their aneurysms, (2) details of the endovascular device used, (3) complications encountered during the procedure and the immediate outcome, (4) results of contrast enhanced computed tomographic imaging at 3, 6, 12, and 18 months after operation and at yearly intervals thereafter, and (5) all adverse events. Life table analysis was performed to determine the cumulative rates of (1) death from all causes, (2) rupture, and (3) late conversion to open repair. Risk factors for rupture and late conversion were identified through regression analysis. Results: By March 2000, 2464 patients had been registered, and their mean duration of follow-up was 12.19 months (SD, 12.3 months). There were 14 patients with confirmed rupture of their aneurysms. The cumulative rate (risk) of rupture was approximately 1% per year. Emergency surgery was undertaken in 12 (86%) patients, of whom five (41.6%) survived. Two patients who were not treated surgically also died, which resulted in an overall death rate of 64.5% (9/14) of the patients. Significant risk factors for rupture were proximal type I endoleak (P =.001), midgraft (type III) endoleak (P =.001), graft migration (P =.001), and postoperative kinking of the endograft (P =.001). Forty-one patients underwent late conversion to open repair with a perioperative mortality rate of 24.4% (10/41). The cumulative rate (risk) of late conversion was approximately 2.1% per year. Risk factors (indications) for late conversion were proximal type I endoleak (P =.001), midgraft (type III) endoleak (P =.001), type II endoleak (P =.003), graft migration (P =.001), graft kinking (P =.001), and distal type I endoleak (P =.001). Conclusions: Endovascular repair of infrarenal aortic aneurysms with the first- and second-generation devices that predominated in this study was associated with a risk of late failure, according to an analysis of observed hard end points of 3% per year. Action taken to address the risk factors identified by the study may improve results in the future. (J Vasc Surg 2000;32:739-49.)

Tuberculosis in Europe: another step forward for international surveillance

Spurred on by the reversal or slowing of the decline in tuberculosis incidence in many countries, the threat of the emergence of multidrug resistant strains of Mycobacterium tuberculosis, and possibly by the success of international AIDS surveillance, European collaborators have completed a pilot study (reported in this issue) of the feasibility of standardising tuberculosis surveillance. Although the case definitions used within countries differ, these differences are unlikely to account for the large variations in the incidence of tuberculosis between countries, ranging in 1995 from 3 per 100 000 in Malta to 102/100 000 in Romania. Equally large differences between countries were observed for the proportions of cases who had been born abroad. The establishment of surveillance for Europe as a whole is likely to strengthen national tuberculosis reporting systems and enable multidrug resistance and the relative effectiveness of control programmes to be monitored closely. When standardised case specific data are shared routinely more sophisticated analyses will be possible, which should enable prevention policies to be selected that will hasten the elimination of “the captain of all these men of death”.

The need for clinical trials of endovascular abdominal aortic aneurysm stent-graft repair: The EUROSTAR Project. EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair.

EUROSTAR (EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair) was established for the purpose of combining and studying data on endovascular abdominal aortic aneurysm (AAA) repair, EUROSTAR is independent of any commercial interest and has as its ultimate goal an independent, scientifically reliable assessment of endovascular AAA grafting. A standardized case record form is used for data collection and transmission, and the database is maintained in a central registry office. A comprehensive set of clinical, imaging, technical, and laboratory data obtained at initial admission and follow-up are recorded; these data are analyzed periodically and reports generated on the collated experience. As a first priority, an observational study without controls was initiated in July 1996 to address the issues of procedural safety, device durability, and long-term effect upon the aneurysms. Several ancillary studies have been initiated, including a "Retrieval and Analysis Study" for the evaluation of explanted devices. While a randomized study does not seem feasible at present, this may be organized at the appropriate time when the devices and techniques become more standardized.

The Need for Clinical Trials of Endovascular Abdominal Aortic Aneurysm Stent-Graft Repair: The EUROSTAR Project

EUROSTAR (EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair) was established for the purpose of combining and studying data on endovascular abdominal aortic aneurysm (AAA) repair, EUROSTAR is independent of any commercial interest and has as its ultimate goal an independent, scientifically reliable assessment of endovascular AAA grafting. A standardized case record form is used for data collection and transmission, and the database is maintained in a central registry office. A comprehensive set of clinical, imaging, technical, and laboratory data obtained at initial admission and follow-up are recorded; these data are analyzed periodically and reports generated on the collated experience. As a first priority, an observational study without controls was initiated in July 1996 to address the issues of procedural safety, device durability, and long-term effect upon the aneurysms. Several ancillary studies have been initiated, including a "Retrieval and Analysis Study" for the evaluation of explanted devices. While a randomized study does not seem feasible at present, this may be organized at the appropriate time when the devices and techniques become more standardized.