Open Surgical Repair
Some AAA patients simply fare better with surgery.
To view the tables that correspond to this article, please refer to the print version of our November/December issue, page 58.
The introduction of endovascular techniques for the repair of abdominal aortic aneurysms (AAAs) has initiated a debate among vascular surgeons in the US. Endovascular aneurysm repair (EVAR) enthusiasts contend that the minimally invasive procedure is safer than open repair and should be considered the first-line therapy whenever possible. More cautious proponents point to the fact that the long-term efficacy of EVAR remains unknown compared to open repair, and that the endovascular approach should therefore be reserved for high-risk patients only (Figures 1 and 2). Regardless of personal opinion, every vascular surgeon needs a working knowledge of the current mortality, morbidity, and outcomes associated with each type of repair. This information is crucial for physicians and patients to determine which procedure is best suited for their particular medical condition, lifestyle, and expectations.
GENERAL INDICATIONS FOR AAA REPAIR
Based on studies performed in the 1960s, AAA repair was indicated for aneurysms with a transverse diameter of 5 cm or greater. However, two recent publications by the Aneurysm Detection and Management Veteran Affairs Cooperative Study Investigators have clearly defined the rupture rate of AAA at various diameters.1,2 These investigators reported a 1% per year rupture rate for AAAs with a maximal diameter of less than 5.5 cm. The 1-year incidence of probable rupture for aneurysms between 5.5 and 5.9 cm was 9.4%; there was a 10.2% rupture rate for aneurysms measuring 6.0 to 6.9 cm; and AAAs greater than 7 cm had a 32.5% rupture rate. AAAs greater than 8 cm had a 6-month rupture rate of 25.7%. These data indicate that due to the low incidence of rupture, physicians can recommend close observation of AAAs with diameters less than 5.5 cm. AAAs between 5.5 and 6.9 cm in size should be repaired promptly, and those greater than 7 cm require urgent repair.
OPEN REPAIR MORTALITY
According to numerous reports, the surgical mortality rate for elective AAA repair ranges between 3.5% and 7.5% (Table 1).3-7 Huber et al recently reviewed the US national inpatient database containing information from 19 states. The investigators identified 16,450 patients between 1994 and 1996 who underwent elective open repair of AAA; patients receiving EVAR were excluded from the analysis.8 The overall surgical mortality rate for AAAs in the US for this time period was 4.2%, with a mean hospital stay of 10±8 days. The investigation determined that mortality rates were independently affected by age, gender, race, and the presence or absence of medical comorbidities including COPD, preoperative renal insufficiency, and carotid occlusive disease. Mortality was not affected by ischemic heart disease or hypertension.
Age had a striking effect in this investigation. Mortality correlated closely with increasing age; patients older than 79 years of age had a 9.2% death rate. Given that the average age of patients requiring AAA repair in this investigation was 70, these data convincingly indicate that the national mortality rate for AAA is probably very close to 4.2%. Furthermore, octogenarians fare even worse with open AAA.
OPEN REPAIR COMPLICATIONS
An overall complication rate of 32.4% is a serious concern for physicians who are considering patients for open repair. According to the Canadian Aneurysm Study Group, complications associated with open repair include postoperative bleeding requiring transfusions (2.3%), limb ischemia (3.5%), graft thrombosis (2.9%), intraoperative emboli (3.3%), stroke (0.6%), cardiac events (15%), MI (5.2%), CHF (8.9%), respiratory failure (8.4%), dialysis dependence (0.6%), diarrhea (7.1%), prolonged ileus (11%), and wound infection (1.5%). Although complications associated with open repair are numerous, they are all inpatient morbidities.
It appears from these data that the incidence of long-term complications with open repair is minimal and that the procedure is durable. However, the long-term durability of open repair has made the true incidence of late complications difficult to determine (Table 2).
It is important to note the potential complications associated with open AAA repair; however, data on patient function and quality of life after open repair are equally important. Williamson et al reviewed 154 open AAA repairs performed between 1990 and 1997.9 The investigators analyzed the patients’ preoperative and postoperative ambulatory status, their independent living status, and their perception of recovery and satisfaction with open repair. This series had an operative mortality rate of 4.0%, the average hospital stay was 10 days, and 11% of patients required transfer to a rehabilitation center for an average of 3.6 months. Williamson et al determined that after open AAA repair, 22% of their patients required assistance with ambulation and 14% were nonambulatory.9 Thirty-three percent of patients reported a decrease in activities of daily living, including driving, shopping, and travel, for up to 33 months after the initial surgery; 18% of patients said they would not undergo the procedure again. As surgeons, we can clearly perform open AAA repair with a low mortality rate. However, these outcome data indicate that a significant percentage of patients will experience changes in their functional status and quality of life. As a result, procedures that address the shortcomings of current open techniques must be investigated.
The early results of EVAR for AAA are considerably better than open repair. The technical success rate in most reported series is more than 90%, with a hospital mortality rate of 1% to 2%. The average duration of hospital stays is 2 days, and overall recovery averages around 11 days.10,11
The major concerns regarding EVAR relate to the periprocedural and late complications; problems include endoleak and endotension, morphologic changes, structural failures, reinterventions, late conversions, postimplant ruptures, and cost-effectiveness. The EUROSTAR registry indicates an endoleak rate of 1.36%, but rates as high as 20% at 1 year have been reported. Large aneurysms can change their longitudinal and transverse lengths after EVAR, resulting in graft migration, limb dislodgement, limb obstruction, and component pullout. Furthermore, there is a low incidence of structural defects, which can lead to endoleak formation and contribute to late ruptures at an annual rate of 1% to 2.3%. At 4 years, 11.3% of EUROSTAR patients had late failures requiring open repair, contributing to an annual conversion rate of 2.8%.
Proponents of EVAR indicate that although the associated complications are numerous, the majority can be repaired with endovascular techniques. Reintervention rates of up to 35% have been reported and vary depending on whether the devices are supported, unsupported, or modular. From an outcomes perspective, the high reintervention rate concerns patients the most; reintervention also adds to the overall cost of the procedure.
Based on the foregoing data, I recommend that the following groups of patients be considered for open repair rather than EVAR:
Patients with unfavorable anatomy. Approximately 40% to 50% of patients are not candidates for EVAR based on anatomic considerations and the limited types of devices currently approved by the FDA.
Male patients <69 years of age without pre-existing renal insufficiency, COPD, or carotid occlusive disease. These patients have a low risk of surgical mortality and can achieve good long-term results with open repair.
Patients who are unable to undergo frequent CAT scans. Those with pre-existing renal insufficiency cannot tolerate contrast dye and therefore should not be considered for EVAR, which requires frequent follow-up CAT scans.
Patients who are unable to comply with close follow-up examination protocols. Those with scheduling or other conflicts that could prevent crucial post-EVAR examinations should consider open repair.
Patients with aneurysms that could be easily repaired with a tube graft. Appropriate anatomy and low risk of surgical mortality makes open repair the better option.
Finally, patient selection is not the only factor indicating whether EVAR is more or less preferable. EVAR should not be performed at institutions that have poor infrastructure and lack the support personnel required for close follow-up of EVAR patients. These centers may be better off continuing to provide exclusively open repair.
Peter J. Pappas, MD, is Associate Professor of Surgery and Chief of the Section of Vascular Surgery at UMDNJ-New Jersey Medical School in Newark, New Jersey. Dr. Pappas may be reached at (973) 972-4599, ext. 4417; email@example.com.
1. Lederle FA, Johnson GR, Wilson SE, et al. Rupture rate of large abdominal aortic aneurysms in patients refusing or unfit for elective repair. JAMA. 2002;287:2968-2972.
2. Lederle FA, Wilson SE, Johnson GR, et al, for the Aneurysm Detection and Management (ADAM) Veterans Affairs Cooperative Study Investigators. Immediate repair compared with surveillance of small abdominal aortic aneurysms. N Engl J Med. 2002;346:1444.
3. Johnston KW. Multicenter prospective study of nonruptured abdominal aortic aneurysm, part II: Variables predicting morbidity and mortality. J Vasc Surg. 1989;9:437-447.
4. Johnston KW, Scobie TK. Multicenter prospective study of nonruptured abdominal aortic aneurysm, part I: Population and operative management. J Vasc Surg. 1988;7:69-81.
5. Cronenwett JL, ed. Abdominal aortic aneurysms. In: The Dartmouth Atlas of Vascular Health Care. Hanover, NH: AHA Press; 2000:66-88.
6. Kazmers A, Jacobs L, Perkins A, et al. Abdominal aortic aneurysm repair in Veterans Affairs medical centers. J Vasc Surg. 1996;23:191-200.
7. Dardik ALJW, Gordon TA, Williams GM, Perler BA. Results of elective abdominal aortic aneurysm repair in the 1990s: A population-based analysis of 2,335 cases. J Vasc Surg. 1999;30:985-995.
8. Huber TS, Wang JG, Derrow AE, et al. Experience in the United States with intact abdominal aortic aneurysm repair. J Vasc Surg. 2001;33:304-311.
9. Williamson WK, Nicoloff AD, Taylor LM, et al. Functional outcome after open repair of abdominal aortic aneurysm. J Vasc Surg. 2001;33:913-920.
10. Buth J for the European Collaborators on Stent Graft Techniques for Abdominal Aortic Aneurysm Repair. Endovascular repair of abdominal aortic aneurysms: Results from the EUROSTAR registry. Semin Interv Cardiol. 2000;5:29-33.
11. Van Marrewijk C, Buth J, Harris PL, et al. Significance of endoleaks after endovascular repair of abdominal aortic aneurysms: The EUROSTAR experience. J Vasc Surg. 2002;35:461-473.