January/February 2011 - SASSiT

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Even after an aneurysm is successfully treated with an endograft, it remains a dynamic entity. The aneurysm will eventually thrombose and, by 12 months, approximately 50 percent of aneurysm sacs have shrunk in diameter. 1. Endoleaks 2. Postimplantation syndrome Patients undergoing endovascular stent graft placement often experience an acute inflammatory syndrome characterized by fever, leukocytosis, elevation of serum Creactive protein (CRP) concentration, and perigraft air during the first week to 10 days after implantation 3. Device migration Device migration is one of the major causes of secondary intervention after endovascular aneurysm repair. If untreated, potential complications include endoleak, aneurysm expansion, and rupture. CLINICAL OUTCOMES Short-term The short-term technical success rate for endovascular aneurysm repair ranges from 83 to over 95 percent. A 2007 systematic review identified four randomized trials of 1532 patients who were considered suitable candidates for either endovascular or open repair of nonruptured abdominal aortic aneurysms larger than 5.0 cm in diameter. 1 The 30 day all-cause mortality was significantly lower with endovascular repair (1.6 versus 4.8 percent, relative risk 0.33, 95% CI 0.17-0.64). The two principle contributing trials to this systematic review were: • The EVAR 1 trial included 1082 patients who were at least 60 years of age, with aneurysms at least 5.5 cm in diameter. At 30 days, mortality was significantly lower with endovascular than with open repair (1.6 versus 4.6 percent, adjusted odds ratio 0.34, 95% CI 0.15-0.74). Endovascular repair was also associated with a significantly shorter hospital stay (7 versus 12 days), although more secondary interventions (additional surgical procedures) were required with endovascular repair (9.8 versus 5.8 percent). • The DREAM trial evaluated 345 patients with aneurysms of at least 5 cm in diameter. There was an almost significant trend toward lower operative mortality with endografting than with surgery (1.2 versus 4.6 percent, risk ratio 0.26, 95% CI 0.03-1.10). Moderate and severe systemic complications (cardiac, pulmonary, renal) were more frequent with open repair (26 versus 12 percent), while moderate and severe local vascular or implant-related complications were more frequent with endovascular repair (16 versus 9 percent). The short-term survival advantage of endovascular repair appears to be much greater when endovascular repair is limited to patients at highest risk from open surgery. This was illustrated in a report of 454 consecutive patients who underwent elective repair (206 endovascular and 248 open surgery) of an abdominal aortic aneurysm. The overall 30-day mortality rates not significantly different for endografting and surgery (2.4 and 4.8 percent, respectively). However, among patients at highest surgical risk (American Society of Anesthesiologists class IV), the 30-day mortality rates were much lower with endovascular repair (4.7 versus 19.2 percent with open surgery). Long term The early survival benefit seen with endovascular repair compared to open repair described above is lost between one and four years, after which survival appears equivalent. This observation was seen in the 2007 systematic review discussed above, which included follow-up of 1473 patients from the DREAM (two years) and EVAR 1 randomized trials (four years) Long term outcomes of patients who have undergone endovascular repair of abdominal aneurysms have been evaluated with and without comparison to patients who have undergone open repair. EVAR-1: In this large, randomized trial, endovascular repair of abdominal aortic aneurysm was associated with a significantly lower operative mortality than open surgical repair. However, no differences were seen in total mortality or aneurysm-related mortality in the long term. Endovascular repair was associated with increased rates of graft-related complications and re-interventions and was more costly. EVAR-2: In this randomized trial involving patients who were physically ineligible for open repair, endovascular repair of abdominal aortic aneurysm was associated with a significantly lower rate of aneurysm-related mortality than no repair. 8
However, endovascular repair was not associated with a reduction in the rate of death from any cause. The rates of graft-related complications and reinterventions were higher with endovascular repair, and it was more costly. Conclusion 1. What are the advantages of EVAR over conventional open repair? The results from EVAR1 and DREAM demonstrate that the short-term morbidity and mortality related to open repair is clearly improved in patients undergoing EVAR. However this benefit does not follow through in the long-term. In the select sub-group of patients with anatomical variants and/or a hostile abdomen EVAR is a very attractive option to avoid the unusually excessive risks of open surgery. 2. What are the potential drawbacks of the novel approach? Higher long-term aneurysm specific morbidity and mortality is in large part due to the Endoleak phenomenon, as discussed earlier. Stent-technology depends on anatomic suitability and while EVAR maybe desirable in a patient it may not be applicable, because of unsuitable anatomy or problems with access. In view of uncertain long-term durability it should be used with caution in younger relatively low risk patients. The anticipated use of EVAR to treat patients who were not fit for open surgery has not been supported by the EVAR2 trial. 3. Does the long-term outcome of the novel approach match the tested outcomes of conventional management? Long-term follow up in both the EVAR1 and DREAM trial demonstrate that morbidity and mortality are equivalent in both groups. However, the aneurysm specific morbidity and mortality was significantly higher in the EVAR arms of the studies. Initial speculation that this was related to the ‘developmental turnaround time’ of new technology, may not hold true as the American-based OVER trial has had very similar results compared to the EVAR1 and DREAM trials despite using the latest stent technology. 4. What are the cost implications of the novel approach? EVAR is more costly than open repair not only because of the initial device costs but also because of the rigorous CT based follow-up used in most of the trials. However, in the EVAR and DREAM trials the long-term costs of all-cause morbidity associated with open repair such as wound complications, were not included in the cost analysis. Moreover, followup surveillance of the stent is moving away from CT towards a duplex based regime which is far more cost effective. In conclusion, the endovascular management of abdominal aortic aneurysms should not be viewed as a replacement for conventional open surgery. EVAR is a weapon in the armamentarium of the vascular surgeon, which if used with caution in the appropriate setting will form part of an effective elective management strategy for the treatment of AAA’s. REFERENCES 1. Sajid MS, Desai M, Baker DM, Hamilton G. Endovascular Aortic Aneurysm Repair (EVAR) Has Significantly Lower Peri-operative Mortality in Comparison to Open Repair: A Systemic Review. Asian J Surg. 2008 Jul;31(3):119-23 2. Malas MB, Freischlag JA. Interpretation of Results of OVER in the context of the EVAR Trial, DREAM, and the EUROSTAR Registry. Semin Vasc Surg. 2010 Sep;23(3):165-9 3. Albuquerque FC Jr, Tonnessen BH, Noll RE Jr, Cires G, Kim JK, Sternbergh WC 3 rd . Paradigm shifts in the treatment of Abdominal Aortic Aneurysms: trends in 721 patients between 1996 and 2008. J Vasc Surg.2010 Jun;51(6):1348- 52; discussion 1352-3. 4. Deaton DH. Future Technologies to address the failed endoprosthesis. Semin Vasc Surg. 2009 Jun;22(2):111-8. 5. Lederle, FA, Johnson, GR, Wilson, SE, et al. The aneurysm detection and management study screening program: validation cohort and final results. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators. Arch Intern Med 2000; 160:1425. 6. Szilagyi, DE, Smith, RF, DeRusso, FJ, et al. Contribution of abdominal aortic aneurysmectomy to prolongation of life. Ann Surg 1966; 164:678. 7. Peppelenbosch, N, Buth, J, Harris, PL, et al. Diameter of abdominal aortic aneurysm and outcome of endovascular aneurysm repair: does size matter? A report from EUROSTAR. J Vasc Surg 2004; 39:288. 8. Greenhalgh, RM, Brown, LC, Kwong, GP, et al. Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR trial 1), 30-day operative mortality results: randomised controlled trial. Lancet 2004; 364:843. 9
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Page 13 and 14: Dysphagia Lusoria: A case of an abe
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Page 19 and 20: Case Report: Spontaneous Aortocaval
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January/February 2011 - SASSiT

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