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Title: A comparison of fenestrated endovascular aneurysm repair (fEVAR) with alternative treatment strategies
Author: Millen, Alistair Mackenzie
ISNI:       0000 0004 7964 1678
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2018
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Introduction: Fenestrated Endovascular Aneurysm Repair (fEVAR) is one of a multitude of treatment options for repairing a juxtarenal aortic aneurysm. Alternative treatment options include open repair using a prosthetic graft and endovascular repair using a standard EVAR device outside the intended manufacturer's indications for use (IFU). Although there is perceived benefit of fEVAR over open repair and assumed deleterious effects of using standard EVAR outside of IFU, it is not known which of these three treatment options would result in the best clinical outcome when treating an aneurysm that would be anatomically outside the IFU for standard EVAR. For simplicity, this type of aneurysm is referred to as a non-standard aneurysm. The hypothesis tested in this thesis is that fEVAR has the best clinical outcome as a treatment strategy for non-standard abdominal aortic aneurysms (AAAs) that are unruptured in whom aneurysm repair is deemed to be more beneficial than conservative management. 'Best clinical outcome' relates to the clinical outcome measures: all-cause mortality, aneurysm related mortality and clinical success as defined by agreed reporting standards throughout all follow up time points. The outcome measures regarding mortality will be weighted equally to each other and clinical success will be weighted less than those pertaining to mortality. Method: To test the hypothesis a retrospective concurrent cohort study was carried out assessing the clinical outcomes of three categories of patients: those treated by traditional open operation, fEVAR, and a standard EVAR performed outside of IFU for non-standard aneurysms. A non-standard aneurysm is defined as one that falls outside the instructions for use for standard EVAR in relation to anatomical features of the aortic neck. Analysis of all patients who underwent aneurysm repair for a 'non-standard aneurysm' in the Cheshire and Merseyside region in the 24-month period 1st April 2006 - 31st March 2008 were to form the basis of data for this study. The preoperative computed tomography (CT) scan of each patient was scrutinised separately by two observers to assess if they met the inclusion criteria i.e. if the aneurysm was outside the IFU for standard EVAR. Patients were excluded from analysis if they had a previous surgical or endovascular repair of their aneurysm or if they exhibited an aneurysm that was anatomically within IFU. Hospital records were then scrutinised to obtain clinical outcome data for each patient according to a proforma. The primary outcome measures included: 30-day mortality/In-hospital mortality, mid-term mortality and aneurysm related mortality, clinical success and technical success. Results: 80 patients were included in the final analysis from two centres performing aneurysm repair in the Cheshire and Merseyside region. 28 patients underwent treatment with standard EVAR (EVAR), 15 with fenestrated EVAR (fEVAR) and 37 patients underwent AAA repair as an open procedure (OR). The median follow up for all patients was 10.7 years. The results of the primary outcome measures are as follows for EVAR, fEVAR and OR, respectively: In hospital mortality, 7.1%, 0%, and 5.4% - no significant difference. Overall survival at 5 years was ; 54%, 57% and 68% - no significant difference. For the whole cohort (22) 29% of patients survived to 10 years and were alive at the end of the study period. Aneurysm related mortality over length of follow up; 10.7%, 0%, 8.1% - no significant difference. Technical success; 75%, 87% and 97% - p= < 0.001. Clinical failure over the course of the entire follow up was; 46%, 7% and 8% - p= < 0.001. None of the secondary outcome measures. Conclusion: Patients who underwent standard EVAR had a significantly worse outcome after their aneurysm repair, attributable to technical success and clinical failure rates. It can therefore be recommended from this study that where possible placement of standard EVAR devices out with IFU should be avoided in preference for an advanced stent-graft technique or open repair. However, it is not possible to accept the hypothesis of this study that fEVAR provides the best clinical outcomes. Further study needs to ascertain the magnitude of any differences in clinical outcomes between OR and fEVAR.
Supervisor: Vallabhaneni, Srinivasa ; Williams, Rachel Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral