Abstract
Endovascular repair (EVAR) represents a useful and validated alternative to conventional surgery in selected patients with abdominal aortic aneurysm (AAA) because it is associated with a significantly lower long-term AAA-related mortality. Data regarding a series of 91 patients (88 men, 3 women, median age 71 years, range 65-82 years) is reported. The patients were divided into three groups, according to the type of implanted stent (Endurant, Excluder and Talent). High American Society of Anesthesiologists Physical Status Classification System (ASA) was important in increasing the likelihood of an early complication (p=0.0007), while it did not have any effect on later adverse events, which were more closely related to the size of the aneurysm (p=0.006). As expected, the aneurysm diameter influenced the endoleak incidence (p=0.011), aneurysmal sac expansion (p=0.029), re-intervention risk (p=0.031) and the success of treatment (p=0.006). A significantly lower tendency for the development of endoleak (p=0.035) and other late complications (p=0.048) was observed in patients with Endurant device. This group seems to be more likely destined to achieve therapeutic success, but the difference was not significant. A borderline significance (p=0.071) with regard to early complications was also recorded. However, the use of this type of device did not affect survival, which was exclusively related to ASA (p=0.040). No other statistically significant differences were found between groups. Since open surgery for elective suprarenal AAA repair is still associated with considerable mortality, EVAR may offer several advantages over open repair surgery, including a less invasive operative procedure, and shortened intensive care unit and hospital stay. The technological improvements of the prosthesis for EVAR will likely reduce complications related to this technique in the near future.
The interest in the endovascular repair (EVAR) of abdominal aortic aneurysms (AAA) has remained high since the time in which the early pioneers conceived the technique, more than 20 years ago (1, 2). Currently, EVAR represents a useful and validated alternative to conventional surgery in selected patients with AAA, because it is associated with a significantly lower long-term AAA-related mortality, although it does not appear to influence overall survival (3). Assuming that we do not have commercial interests in regard to any pharmaceutical manufacturer and taking reasonable account of the evolution of endoprostheses and different length of follow-up between older and more recent procedures, the primary end-point of our study was to evaluate therapeutic success achieved using three types of devices.
Patients and Methods
Study population. Data regarding a series of 114 consecutive patients with infra-renal AAA who underwent EVAR at out Institution were reviewed. Six patients who stopped check-up visits were considered lost to follow-up. Initially, 17 patients were treated with eight different types of prosthesis, were also excluded from this retrospective study. The remaining 91 patients (88 men, 3 women; median age 71 years, range 65-82 years) were divided into three groups, according to the type and generation of implanted stent.
Group 1 consists of 22 patients with an Endurant© device (Medtronic, Minneapolis, MN, USA), characterized by controlled release of the suprarenal stent, with anchor pins for suprarenal fixation and highly angulated neck adaptability. Group 2 includes 29 patients with an Excluder© device (Gore, Newark, DE, USA), a prosthesis equipped with infra-renal anchoring. Group 3 includes 40 patients who were treated with a Talent© device (Medtronic, USA), characterized by the absence of anchoring hooks.
Parameters considered in the study. The following parameters were recorded: age of the patients, diameter of the aneurysm, early (within 12 months) and late complications, such as intra-prosthetic thrombosis, ischemia due to perfusion failure, infection or migration of the prosthesis, endoleak formation or expanding aneurismal sac, and possible reoperations required. Patients without significant complications, who did not undergo any further therapeutic treatment for AAA, as well as those with spontaneously-resolved and stable endoleak, were considered as having a therapeutic successes. Medical history, analysis of risk factors and clinical status at the time of commissioning notes were carefully evaluated for the calculation of the anesthesiologic risk, according to the American Society of Anesthesiologists Physical Status Classification System (ASA) (4).
The post-EVAR radiological surveillance was performed according to the protocol previously described, which includes repeated angio-computed tomographic (CT) abdominal scanning and contrast-enhanced ultrasound, at 1, 6 and 12 months after EVAR and then annually, performed paired or alternatively depending on the presence of complications (5). The duration of follow-up was calculated from the time of the procedure until the last radiological examination for the evaluation of therapeutic success or until the patient's death, or to the date of the survival analysis.
Statistical analysis. The baseline characteristics of patients are expressed by the mean±standard deviation (SD) for continuous variables and as frequencies (%) for categorical variables. The chi-square (χ2) test, the Fisher's exact test and Student's t-test were used for comparisons between groups, where appropriate. The odds ratio (OR) was also obtained, and the 95% confidence interval (CI) was used to estimate the precision of the OR. Statistical significance was set at p<0.05. Statistical calculations were performed with JMP© software, version 9 (SAS Institute, Cary, NC, USA).
Results
Table I shows the main characteristics of each group and the results, which were adjusted for length of follow-up and different risk factors, such as ASA >2 and diameter of the aneurysm. Eleven (12.1%) patients required a reoperation and a therapeutic success was obtained in 73 (80.2%) patients. The overall perioperative mortality was 1.1% and 24 (26.4%) further patients died during follow-up due to causes not related to the procedure. The high ASA was important in increasing the occurrence probability of an early complication (p=0.0007), while it did not effect later adverse events, which were more closely-related to the size of the aneurysm (p=0.0061). As expected, the aneurysm diameter influenced the endoleak incidence (p=0.011), aneurysmal sac expansion (p=0.029), re-intervention risk (p=0.031) and success of treatment (p=0.006).
A significantly lower tendency for the development of endoleak (Group 2 vs. 1: OR=5.99, 95%CI 1.11-51.53, p=0.035; Group 3 vs. 1: OR=13.36, 95%CI 2.70-109.81, p=0.0008) and other late complications (Group 2 vs. 1: OR=5.29, 95%CI 0.98-45.36, p=0.048; Group 3 vs. 1: OR=10.06, 95%CI 2.09-81.41, p=0.003) was observed in Group 1 (Figure 1).
Demographic, pre-operative data and outcomes in the three groups of patients.
This group seems to be more likely destined to achieve therapeutic success (Group 2 vs. 1: OR=2.73, 95%CI 0.55-16.73, p=0.22; Group 3 vs. 1: OR=2.81, 95%CI 0.60-16.77, p=0.19), but the difference was not significant. However, the use of this type of device did not affect survival (Group 2 vs. 1: OR=2.41, 95%CI 0.55-10.43, p=0.31; Group 3 vs. 1: 3.05, 95%CI 0.76-12.19, p=0.13), which was exclusively related to ASA (p=0.040). A borderline significance with regard to early complications (OR=3.24, 95%CI 0.89-13.15, p=0.074) between Group 2 vs. 1 was observed. No other statistically significant differences were found between groups.
Discussion
In recent years, the applicability of EVAR has expanded and currently up to 80% of patients with AAA are suitable for this type of treatment (6). A number of variables can affect the results of EVAR, including endovascular treatment indications, which to date have vague enlistment limitations. Thus, definitive data on real outcome after EVAR seem quite far, because of the technological development of devices. In any case, EVAR represents a safe and efficacious treatment for AAA with low (1-2%) perioperative mortality (7). In our series, only one patient (1.1%) died of causes related to EVAR. He had a 5-cm AAA, but the positioning of the device was particularly difficult, due to the extreme tortuosity of the iliac arteries bilaterally, which required the use of a bilateral brachial access and repeated introduction and expansion maneuvers. The high ASA of the patient, the overall intervention duration and the subsequent need for open surgery required admission to the intensive care unit, and the patient was dead a few days later.
Aneurysm size and endograft type represent independent predictive factors affecting absolute volume change after EVAR for AAA, regardless of endoleak presence (8). We observed only one case (Group 3) of endotension and increased aneurysm volume without radiological demonstration of endoleak. Using the maximum aneurysm diameter as the main parameter an excellent risk score for discriminating aortic complication can be achieved (9). As for the devices in use, based on our experience and in agreement with the results from most studies, the better prosthesis performances has markedly improved the outcomes (10). Endoleak is the most frequent complication of EVAR, occurring in up to 50 % of cases (5, 11). Postoperative endoleak and the need for re-intervention continue to be challenging problems for patients after EVAR (12). Overall, during follow-up 32 out of 91 patients (35.1%) developed endoleak, with significant differences (p<0.05) between groups, ranging from 9.1% (Group 1) to 52.5% (Group 3). Recently it has been suggested that the risk of prosthesis migration and endoleak is reduced when devices with secure fixation systems (i.e. Endurant and Excluder devices) are used (6). In our study, Endurant represented the newer prosthesis, and patients treated with this device (Group 1) reached a 86.3% therapeutic success rate, higher than that obtained in other groups, but the difference was not statistically significant.
Three-dimensional (3D) computed tomography angiography (CTA) images in a 68-year-old man presenting a huge type 3 endoleak due to main body graft rupture and disconnection. A and B: Volume rending technique (VRT) and maximum intensity projection (MIP) images, respectively. C: longitudinal-section contrast-enhanced ultrasound (CEUS) image. There is an overlapping between CTA and CEUS images in depicting graft disconnection and extravasation contrast media (arrow) in the aneurysmal sac around the graft (G).
Several studies have shows that endoleak incidence, first-generations endoprosthesis and AAA diameter (>5.5 cm) represent the main factors affecting the risk of post-EVAR rupture, need of re-intervention, and the final therapeutic success (13). However, the majority of endoleaks can be treated with endovascular techniques, but open surgical interventions may be required in selected patients (14). In six (6.6%) cases of this series, with the aim of preserving the prosthesis, further procedures were required, such as positioning of proximal cuff, expansion of prosthetic branches with a balloon, embolization of the afferent arteries supplying the aneurysmal sac, thrombolysis, or surgical femoro-femoral by-pass because the iliac prosthesis branch thrombosis. Because of other prosthesis complications (i.e. infection), or endovascular untreatable or unresolved endoleaks, further five (5.5%) patients underwent open surgical removal of the previously positioned device. However, it should be noted that according to our results, the high rate of successful treatment does not actually affect survival, which is in fact closely related to the patient's preoperative clinical condition and comorbidities. This proves that technological evolution should not divert attention from the fundamental principle that accurate patient selection and strict respect of enrollment indications can make a medical treatment into a highly effective therapy.
Conclusion
Since open surgery for elective suprarenal AAA repair is still associated with considerable mortality, EVAR may offer several advantages over open repair, including a less invasive operative procedure, reduced transfusion requirements, and shortened intensive care unit and hospital stay (15, 16). Long-term follow-up is required to diagnose and treat endoleaks before they result in post-EVAR complications, such as endoleak or aneurysm rupture (14). Further technological improvements of prostheses for EVAR will likely reduce complications related to this technique in the near future.
Footnotes
-
Conflicts of Interest
The Authors declare that they have no conflicts of interest and no funding was obtained for this case series.
- Received November 4, 2013.
- Revision received November 27, 2013.
- Accepted November 28, 2013.
- Copyright © 2014 The Author(s). Published by the International Institute of Anticancer Research.
References
In this issue
Jump to section
Related Articles
Cited By...
- No citing articles found.