This Article Abstract Full Text (PDF) All Versions of this Article: 106/7/782    most recent 01.CIR.0000028603.73287.7Dv1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Teufelsbauer, H. Articles by Huk, I. Search for Related Content PubMed PubMed Citation Articles by Teufelsbauer, H. Articles by Huk, I. Related Collections CV surgery: aortic and vascular disease

(Circulation. 2002;106:782.)
© 2002 American Heart Association, Inc.

Clinical Investigation and Reports

Endovascular Stent Grafting Versus Open Surgical Operation in Patients With Infrarenal Aortic Aneurysms

A Propensity Score–Adjusted Analysis

Harald Teufelsbauer, MD; Alexander M. Prusa, MD; Klaus Wolff, MD; Peter Polterauer, MD; Josif Nanobashvili, MD; Manfred Prager, MD; Thomas Hölzenbein, MD; Siegfried Thurnher, MD; Johannes Lammer, MD; Michael Schemper, PhD; Georg Kretschmer, MD; Ihor Huk, MD

From the Department of Vascular Surgery (H.T., A.M.P., K.W., P.P., J.N., M.P., T.H., G.K., I.H.), Department of Interventional Radiology (S.T., J.L.), Department of Medical Computer Sciences (M.S.), and Ludwig Boltzmann Research Institute of Interdisciplinary Clinical Vascular Medicine (H.T., P.P., G.K., I.H.), University of Vienna–Medical School, Vienna, Austria.

Correspondence to H. Teufelsbauer, MD, Department of Vascular Surgery, University of Vienna–Medical School, Waehringer Guertel 18-20, Vienna, Austria. E-mail alexanderprusa{at}hotmail.com

	Abstract

Top Abstract Introduction Methods Results Discussion References

 
Background— Although transfemoral endovascular aneurysm management (TEAM) of infrarenal abdominal aortic aneurysms (AAA) is widely performed, open graft replacement is still considered the standard of care. The aim of this study was to investigate whether clear indications for TEAM can be established in patients with significant comorbidities without investigating differences in relative procedure efficacy or durability.

Methods and Results— A propensity score–based analysis of 454 consecutive patients treated electively for AAA from January 1995 through December 2000 was performed. Of those 454 patients, 248 received open surgery and 206 received TEAM. In-hospital mortality rates (MRs) were compared. After adjusting for propensity scores, a Cox proportional hazard model (COX) was employed to test the influence of the respective treatment on postoperative 900-day survival estimates (SEs). Several potential preoperative risk factors were used as covariates. The MR of all patients was 3.7%. Explorative analysis demonstrated that patients treated by TEAM presented with significantly more risk factors. In American Society of Anesthesiologists class IV patients, a significant difference in MR was detected (4.7% for TEAM versus 19.2% for open surgery; P<0.02). After adjusting for the propensity to receive TEAM or open surgery, a regression analysis of survival based on COX revealed predictive influences of impaired kidney (P<0.047) or pulmonary function (P<0.001), increased age (P<0.05), and selection of treatment modality (P<0.002) on SE.

Conclusions— TEAM represents a less invasive procedure for AAA therapy in patients with significant preoperative risk factors. Especially in geriatric patients with multiple morbidities, TEAM offers a method of therapy with acceptable MRs and SEs, making active treatment possible in otherwise incurable patients.

Key Words: aorta • aneurysm • stents • risk factors • mortality

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
Endovascular repair was introduced early in the last decade for the treatment of infrarenal abdominal aortic aneurysm (AAA).^1,2 Because it is obviously less invasive,³ transfemoral endovascular aneurysm management (TEAM) has been used with growing frequency.^4–9 Remarkable progress in the development of the stent graft design can be observed.^10–12 Nevertheless, a high incidence of endoleaks,^8,12 and therefore incomplete exclusions of the aneurysm as well as the lack of long-term results,^5,6,9,11 are the main discouraging factors. Furthermore, only about half of the patients are eligible for the endoluminal approach because of the anatomy of the aneurysm sac.³ Thus, TEAM has not been accepted as standard treatment of AAA so far, and even has been called a "failed experiment."¹³ Postoperative results of TEAM are derived from pooled series or originate from international multicenter registries like EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair (EUROSTAR).⁸ Postoperative mortality rates of 3%^5,8,11,12 have been reported.

After open surgical repair, postoperative mortality rates were impressively reduced, and rates as low as 2% to 5% have been published in recent series,^14–20 particularly in low-risk patients. However, age, female sex, and some organ dysfunctions are factors responsible for adverse outcome. In patients with advanced age, especially in octogenarians with significant comorbidities, mortality rates are still disappointing—between 6% and 14%.^{14,15,18,19,21–26}

Cumulative results of both treatments suggest similar early postoperative outcomes in general. The few studies published so far comparing TEAM with open surgery^5,6,9,27 were unable to reveal significant differences in overall midterm survival rates. In these studies, the number of patients was limited and analyses considering risk profiles were not performed. At present, sufficient data to recommend either method of treatment on the basis of individual risk factors is not available.

Thus, the aim of this single-center analysis was to test whether TEAM, because of the reduced invasiveness, may improve postoperative mortality in high-risk patients, especially in geriatric patients with respective comorbidities, as compared with conventional open surgery.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
Patients
From January 1995 to December 2000, 454 consecutive patients were treated electively for infrarenal aortic aneurysms. Patients with thoracoabdominal or juxtarenal aortic aneurysms, as well as those requiring cross-clamping above the renal arteries, were excluded. The clinical series consisted of 412 men and 42 women with a median age of 72 years (range: 32 to 95 years; interquartile range: 66 to 76 years). In 248 patients (54.6%), the classical graft replacement technique of the dilated aortic segment was used, whereas the other 206 patients (45.4%) received TEAM. If anatomic preconditions of the iliac arteries were suitable for implantations of stent grafts, the decision to use the open or closed repair was left to the surgeon’s preference. Patients’ data were collected prospectively.

Besides an age above the median, sex, and several preoperative risk factors, the type of the surgical procedure was analyzed with regard to in-hospital mortality and 900-day survival rates. Renal dysfunction was considered to be present in patients with serum levels of creatinine exceeding 1.5 mg/dL. Pulmonary dysfunction was assumed when the results of lung function tests were below 65% of the expected values, and/or moderate or severe dyspnea on exertion was found. Hepatic dysfunction was indicated by serum levels of -glutamyl transpeptidase (GGT) exceeding 30 IU/L. The respective cut-off levels were chosen according to internationally accepted limits, as well as the normal values of our Department of Laboratory Medicine. Furthermore, history of heart disease, including myocardial infarction, stable angina pectoris, balloon dilatation of coronary arteries, bypass grafting, evidence of reduced ventricular performance, and presence of pulmonary hypertension, was defined as a cardiac risk factor. Additionally, diabetes, hypertension, smoking, and evidence of severe cerebrovascular disease were used as further risk factors. In patients with clear indications for revascularization of coronary or carotid arteries, the respective interventional or operative repair was done before exclusion of AAA. Patients presenting with untreatable unstable angina pectoris, New York Heart Association class IV function, necessity of O₂-support at rest, or end-stage malignant disease were not treated for their AAA. American Society of Anesthesiologists (ASA) scoring²⁸ was used to estimate overall status of health of the individual patient.

With regard to survival data, the most recent information is periodically obtained from the Austrian Central Bureau of Statistics (Oesterreichisches Statistisches Zentralamt) in Vienna. Federal Austrian law demands that all deaths be reported to this institution. At least once a year, all data are transferred to the mainframe computer of the Medical Faculty of the University of Vienna. The last upgrade of data was performed on January 1, 2001.

Surgical Technique
For open surgery, a transperitoneal approach via a median laparotomy was used. Exclusion of AAA was performed by implantation of commercially available bifurcated (n=108) or tubular grafts (n=140). Inclusion technique was used for aortic anastomoses. End-to-end or end-to-side technique was applied for the iliac or femoral distal suture lines.

Endoluminal stent grafting was achieved by a transfemoral approach (n=206). The common femoral artery of one side was surgically exposed. Afterward, commercially available modular stent grafts (Stentor, Vanguard, Talent, Excluder, and Zenith) were implanted through an arteriotomy. In case of bifurcated stent grafts (n=181), the extension graft for the second limb was inserted by transcutaneous puncture or arteriotomy of the contralateral common femoral artery. Intraluminal positioning and deployment of all stent grafts took place under fluoroscopic guidance in specially equipped theaters or angiography suites.

Statistical Analysis
For basic description, age was expressed as median, interquartile range, and absolute range. Significant differences were checked by the Mann-Whitney rank sum test. All categorical data were displayed as frequencies and percentages. We performed ² tests for bivariate analysis of categorical data. If appropriate, adjustments of probability values for multiple testing were done by a resampling technique. Survival estimates were calculated by Kaplan-Meier method. Cox proportional hazard modeling was used for unadjusted and adjusted survival analysis. To adjust for the bias inherent to the decision of choosing TEAM or open surgery, propensity scores²⁹ were used. Propensity analysis aims to identify patients with similar probability of receiving TEAM on the basis of observed clinical characteristics. With the use of a multivariable logistic regression model that includes basic risk parameters as the independent variables, the probability of a patient’s being assigned to TEAM therapy was determined. The goodness-of-fit of the propensity score model was obtained by c statistics. The variables included in the propensity score model were age, renal dysfunction (serum creatinine 1.5 mg/dL), pulmonary dysfunction, liver dysfunction (GT 30 IU/L), cardiac disease, cerebrovascular disease, history of malignant disease, and estimation of the actual physical status by ASA scoring. The population was then divided into quintiles according to the propensity score. Within each quintile, the mean propensity scores of TEAM and open surgery groups were compared, as were their clinical and procedural characteristics. To adjust for the heterogeneity between the 2 groups, the propensity score was then entered as a continuous variable in the Cox proportional hazards model, along with the type of operation and 12 potential covariates as listed in Table 1. These covariates included the baseline variables entered in the propensity score model and other procedural variables that might correlate with outcome: namely, sex, diabetes, hypertension, and history of smoking. The validity of the proportional hazards assumption was tested with the introduction of a time-dependent explanatory variable to check increasing or decreasing trends in hazard ratio over time. All statistical analyses were performed with the SAS program (version 6.09E) on an IBM 4090 mainframe.

View this table: [in this window] [in a new window]   Table 1. Demographic Data, Prevalence, and Distribution of Preoperative Risk Factors

	Results

Top Abstract Introduction Methods Results Discussion References

 
The overall mortality rate in hospital or within the first 30 postoperative days for all patients was 3.7%. After TEAM and open aneurysm repair, the mortality rates were 2.4% and 4.8%, respectively. Figure 1 shows similar probabilities of survival in patients followed up for 900 days (P<0.769) after both modalities of treatment.

View larger version (11K): [in this window] [in a new window]   Figure 1. Probability of survival estimated according to Kaplan-Meier (in percentages) after open surgery vs TEAM in all patients.

Table 1 shows the distribution of the preoperative risk factors in the 2 groups of patients. As expected, significantly higher prevalences in most of the investigated preoperative risk factors were found in the endoluminally treated group.

Figure 2 illustrates the different treatment modalities as preferentially used in the various age groups. Using ASA staging, significantly more high-risk patients (ASA class IV) received TEAM (41.3% TEAM versus 10.5% open surgery; P<0.001), whereas most patients in ASA classes I and II underwent open surgery (35.5% open surgery versus 4.9% TEAM; P<0.001).

View larger version (22K): [in this window] [in a new window]   Figure 2. Distribution of age in patients receiving open surgery vs TEAM.

Figure 3 summarizes results of subgroup analysis of the significant preoperative risk factors with regard to 900-day mortality. Only patients with reduced physical status classified as ASA IV showed a significant increased hazard ratio (2.3; P<0.028) after undergoing open surgery.

View larger version (32K): [in this window] [in a new window]   Figure 3. Comparison of open surgery and TEAM 900-day mortality rates stratified by subgroups.

Figure 4 gives Kaplan-Meier estimates of survival after TEAM compared with those after open surgery in ASA class IV patients (P<0.0275). Similarly, there was a significant difference between TEAM and open surgery with regard to in-hospital mortality rates (4.7% versus 19.2%; P<0.02).

View larger version (12K): [in this window] [in a new window]   Figure 4. Probability of survival estimated according to Kaplan-Meier (in percentages) after open surgery vs TEAM in ASA class IV patients.

According to propensity score analysis, the decision to choose TEAM or open surgery depends on, in descending order, ASA scoring, cerebral risk, cardiac risk, age, renal dysfunction, malignant disease, hepatic dysfunction, and pulmonary dysfunction. The c statistic for goodness-of-fit of the propensity score model was 0.78, indicating that an acceptable discrimination between the 2 treatment groups was achieved. After splitting in quintiles, propensity scores and the investigated covariates were similar in the two treatment groups.

Adjusted for propensity scores and covariates, a Cox proportional hazard model revealed a significant influence of the type of operation on the 900-day mortality rate. Table 2 illustrates the results of this analysis. Furthermore, Table 3 shows the other significant predictors for increased mortality rates, ie, renal dysfunction, pulmonary dysfunction, diabetes, and age. No decreasing or increasing trends in risk ratio were found, indicating no violation of the proportional hazard assumption.

View this table: [in this window] [in a new window]   Table 2. Hazard Ratio Regarding 900-Day Mortality of Patients Who Have Undergone TEAM versus Open Surgery

View this table: [in this window] [in a new window]   Table 3. Independent Predictors for Mortality at 900 Days After Operation Adjusted for Covariates and Propensity Scores

With regard to in-hospital mortality rates, Table 4 shows a descriptive contingency table analysis. The a priori hypothesis that TEAM offers superior outcome in geriatric high-risk patients is demonstrated. Even after correction for multiple testing by a resampling technique, a significance level of P<0.05 is still achieved.

View this table: [in this window] [in a new window]   Table 4. Descriptive Analyses of In-Hospital Mortality Rates According Either to Age and Significant Risk Factors or to ASA Scoring

Reinterventions (ie, overstenting) because of primary type I or III endoleaks were performed in 7.3% of the patients. Secondary type I or III endoleaks were treated in 9.7% of patients during a 900-day follow-up period after TEAM. Type II endoleaks were observed in 18% of the patients. Secondary rupture occurred in 7 patients (3.4%; Vanguard n=5, Stentor n=1, Talent n=1), whereas 3 of them receiving open repair died postoperatively. In the meantime, both Vanguard and Stentor devices were withdrawn from the market and are no longer commercially available.

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
Open surgery with conventional graft replacement of the aneurysmatic aortic segment either by implantation of tubular or bifurcated grafts is still the standard of care for AAA.¹⁷ The aim of this prophylactic treatment is to prolong survival by balancing the risk of rupture with exsanguinating hemorrhage and death against the expected postoperative mortality. Reduction of postoperative mortality rates is assigned to the progress in operative technique, ie, preferential use of tube grafts instead of bifurcation prostheses, the introduction of blood saving devices, and amelioration of intra- and perioperative management.^18,20 Having survived the first postoperative year, subsequent life expectancy seems to be influenced primarily by underlying diseases rather than by this procedure itself.^{16,17,19,20,24,30,31} Nevertheless, open surgery represents a major burden, causing hemodynamic instability and reperfusion injury³² due to aortic clamping and declamping, with respective demands on physiological compensation mechanisms. Thus, superior early postoperative mortality rates between 1% and 2% are only achieved in low-risk patients with better compensating capabilities but without significant organ dysfunctions.^14,15,20 As previously shown,^14,15,18,33 we were also able to demonstrate that advanced age and renal or pulmonary dysfunction adversely influence postoperative outcome. In our series, younger patients without these risk factors revealed a postoperative mortality rate below 1%, whereas geriatric patients under the strain of such risk factors had unacceptably high mortality rates approaching 20%.

Studies comparing TEAM with open surgery have not been able to show significant differences in early overall postoperative survival rates.^5,6,9,27 Similarly, Kaplan-Meier estimates without risk stratification revealed no clinical relevant differences in midterm survival rates.³⁴ Only parameters of morbidity such as less blood loss, reduced need for blood replacement, and decreased length of stay in the intensive care unit and the hospital could be proved.^5,6,34 In reconsideration of other clinical investigations, the inability to find statistically different mortality rates or the lack of proof of any difference might be caused by the absence of statistical power due to the small clinical effects in insufficient numbers of patients; ie, 2% difference in overall mortality rate may be expected, which would require the recruitment of >1500 patients in each treatment group to achieve sufficient statistical power. Similarly, Sicard et al³⁴ recently compared TEAM with open surgery in 470 patients. All patients and, as a subgroup, those 80 years of age were investigated without evaluation of individual risk profiles. Again, significant differences were only found in parameters of morbidity, and only a trend toward reduced mortality rates in octogenarians was revealed.

In our patients, overall early postoperative mortality and midterm survival rates also showed no significant differences. Our further analyses, however, implied that individual profiles of risk factors, corrected for the basic demographic parameters of age and sex and for parameters of organ dysfunctions, are covariates, as these are expected to influence a priori survival rates in general as well as after open surgical repair of AAA.^18,21–26 Furthermore, propensity score–based analysis was intended to reduce bias caused by the surgeon’s decision-making and to control for systematic differences between the 2 treatment groups. Logistical regression analysis was used as multivariate tool for obtaining propensity scores.^29,35 After stratification in quintiles, similar distributions of risk factors within the quintiles could be observed, thus representing adequate counterbalance by propensity scores.

A Cox proportional hazard regression model adjusted for propensity scores showed that the less invasive endoluminal treatment significantly reduced the 900-day mortality rates. Similarly, early postoperative mortality rates in patients with significant preoperative risk factors are unfavorably high for elective surgical procedures. Notably, in those patients with high individual operative risk (ie, classified as ASA IV), TEAM offers the only possibility for elective treatment with acceptable clinical results. The argument that absence of well-documented long-term results prohibits the use of TEAM as therapy of AAA seems unacceptable in the subgroup of high-risk patients with reduced life expectancy. TEAM is the only therapeutic option in otherwise incurable patients, especially in geriatric patients with large aneurysms and an excessive profile of risk factors.

In our present analysis, a priori differences in the health status of patients in both treatment groups have to be expected because there was the institutional policy to treat patients with reduced health status endoluminally. Simple descriptive analysis strengthened the assumption that patients receiving TEAM presented with significantly more risk factors. Statistically, propensity-adjusted analysis was performed to reduce bias caused by this fact. Nevertheless, a remaining kind of retrospective bias has to be supposed. However, in light of the unacceptable mortality rates in ASA class IV patients, a prospective, randomized clinical trial seems ethically unjustified, and the remaining bias has to be accepted when treating high-risk patients.

In conclusion, no clinically relevant difference in early and midterm postoperative survival rates after TEAM or open surgical exclusion of AAA in younger patients without significant preoperative risk factors could be found. In patients presenting with significant preoperative risk factors, however, especially those with advanced age, only TEAM allows elective surgical treatment of AAA with acceptable postoperative mortality rates. Thus, we suggest that the presence of renal or pulmonary dysfunctions, especially in geriatric or ASA class IV patients, is a clear indication for the application of endoluminal repair. In patients with moderate risk factors (eg, those classified ASA III) the early postoperative outcome after TEAM seems to be slightly superior as compared with open surgery. Given the high incidence of endoleaks, however, the clinical significance of this difference has to be proved in a prospective way to achieve reliable, evidence-based decision-making about which procedure to select in patients with moderate risk factors.

	Footnotes

 
This article originally appeared Online on July 29, 2002 (Circulation. 2002;106:r15– r20).

Received May 28, 2002; revision received June 24, 2002; accepted June 25, 2002.

	References

Top Abstract Introduction Methods Results Discussion References

 
1. Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysms. Ann Vasc Surg. 1991; 5: 491–499.[CrossRef][Medline] [Order article via Infotrieve]

2. Volodos NL, Karpovich IP, Troyan VI, et al. Clinical experience of the use of self-fixing synthetic prostheses for remote endoprosthetics of the thoracic and the abdominal aorta and iliac arteries through the femoral artery and as intraoperative endoprosthesis for aorta reconstruction. Vasa. 1991; 33: 93–95.[CrossRef]

3. Blum U, Lammer J, Polterauer P, et al. Endoluminal stent-grafts for infrarenal abdominal aortic aneurysms. N Engl J Med. 1997; 336: 13–20.[Abstract/Free Full Text]

4. Kretschmer G, Lammer J, Polterauer P, et al. The first 15 months of transluminal abdominal aortic aneurysm management: a single centre experience. Eur J Vasc Endovasc Surg. 1997; 14: 24–32.[Medline] [Order article via Infotrieve]

5. Moore WS, Kashyap VS, Vescera CL, et al. Abdominal aortic aneurysm: a 6-year comparison of endovascular versus transabdominal repair. Ann Surg. 1999; 230: 298–306.[CrossRef][Medline] [Order article via Infotrieve]

6. Quinones-Baldrich WJ, Garner C, Caswell D, et al. Endovascular, transperitoneal, and retroperitoneal abdominal aortic aneurysm repair: results and costs. J Vasc Surg. 1999; 30: 59–67.[CrossRef][Medline] [Order article via Infotrieve]

7. Hölzenbein TJ, Kretschmer G, Polterauer P, et al. Endovascular AAA treatment: expensive prestige or economic alternative? Eur J Vasc Endovasc Surg. 1997; 14: 265–272.[CrossRef][Medline] [Order article via Infotrieve]

8. EUROSTAR Data Registry Center. Progress report August 2000. Available at: http://www.csvs.org/international/Eurostar.htm. Accessed July 15, 2002.

9. Cohnert TU, Oelert F, Wahlers T, et al. Matched-pair analysis of conventional versus endoluminal AAA treatment outcomes during the initial phase of an aortic endografting program. J Endovasc Ther. 2000; 7: 94–100.[CrossRef][Medline] [Order article via Infotrieve]

10. May J, White GH, Waugh R, et al. Adverse events after endoluminal repair of abdominal aortic aneurysms: a comparison during two successive periods of time. J Vasc Surg. 1999; 29: 32–37.[CrossRef][Medline] [Order article via Infotrieve]

11. Hölzenbein TJ, Kretschmer G, Polterauer P, et al. Midterm durability of abdominal aortic aneurysm endograft repair: a word of caution. J Vasc Surg. 2001; 33 (suppl 2): S46–S54.[CrossRef][Medline] [Order article via Infotrieve]

12. Buth J, Laheij RJ. Early complications and endoleaks after endovascular abdominal aortic aneurysm repair: report of a multicenter study. J Vasc Surg. 2000; 31: 134–146.[CrossRef][Medline] [Order article via Infotrieve]

13. Collin J, Murie JA. Endovascular treatment of abdominal aortic aneurysm: a failed experiment. Br J Surg. 2001; 88: 1281–1282.[CrossRef][Medline] [Order article via Infotrieve]

14. Calligaro KD, Azurin DJ, Dougherty MJ, et al. Pulmonary risk factors of elective abdominal aortic surgery. J Vasc Surg. 1993; 18: 914–920.[CrossRef][Medline] [Order article via Infotrieve]

15. Golden MA, Whittemore AD, Donaldson MC, et al. Selective evaluation and management of coronary artery disease in patients undergoing repair of abdominal aortic aneurysms: a 16-year experience. Ann Surg. 1990; 212: 415–420.[Medline] [Order article via Infotrieve]

16. Feinglass J, Cowper D, Dunlop D, et al. Late survival risk factors for abdominal aortic aneurysm repair: experience from fourteen Department of Veterans Affairs hospitals. Surgery. 1995; 118: 16–24.[CrossRef][Medline] [Order article via Infotrieve]

17. Ernst CB. Abdominal aortic aneurysm. N Engl J Med. 1993; 328: 1167–1172.[Free Full Text]

18. Kazmers A, Perkins AJ, Jacobs LA. Outcomes after abdominal aortic aneurysm repair in those > or =80 years of age: recent Veterans Affairs experience. Ann Vasc Surg. 1998; 12: 106–112.[CrossRef][Medline] [Order article via Infotrieve]

19. Katz DJ, Stanley JC, Zelenock GB. Operative mortality rates for intact and ruptured abdominal aortic aneurysms in Michigan: an eleven-year statewide experience. J Vasc Surg. 1994; 19: 804–815.[Medline] [Order article via Infotrieve]

20. Pfeiffer T, Reiher L, Grabitz K, et al. Results of conventional surgical therapy of abdominal aortic aneurysms since the beginning of the "endovascular era." Chirurg. 2000; 71: 72–79.[CrossRef][Medline] [Order article via Infotrieve]

21. Dean RH, Woody JD, Enarson CE, et al. Operative treatment of abdominal aortic aneurysms in octogenarians: when is it too much too late? Ann Surg. 1993; 217: 721–728.[Medline] [Order article via Infotrieve]

22. Ritter R, Grabitz K, Godehardt E, et al. Long-term survival after abdominal aortic aneurysm repair in octogenarians. Gefaesschirurgie. 1997; 2: 5–10.

23. Soisalon-Soininen SS, Salo JA, Mattila SP. Abdominal aortic aneurysm surgery in octogenarians. Vasa. 1998; 27: 29–33.[Medline] [Order article via Infotrieve]

24. O’Hara PJ, Hertzer NR, Krajewski LP, et al. Ten-year experience with abdominal aortic aneurysm repair in octogenarians: early results and late outcome. J Vasc Surg. 1995; 21: 830–837.[CrossRef][Medline] [Order article via Infotrieve]

25. Chalmers RT, Stonebridge PA, John TG, et al. Abdominal aortic aneurysm in the elderly. Br J Surg. 1993; 80: 1122–1123.[Medline] [Order article via Infotrieve]

26. Harris KA, Ameli FM, Lally M, et al. Abdominal aortic aneurysm resection in patients more than 80 years old. Surg Gynecol Obstet. 1986; 162: 536–538.[Medline] [Order article via Infotrieve]

27. May J, White GH, Waugh R, et al. Improved survival after endoluminal repair with second-generation prostheses compared with open repair in the treatment of abdominal aortic aneurysms: a 5-year concurrent comparison using life table method. J Vasc Surg. 2001; 33 (suppl 2): S21–S26.[CrossRef][Medline] [Order article via Infotrieve]

28. Keats AS. The ASA classification of physical status: a recapitulation. Anesthesiology. 1978; 49: 233–236.[Medline] [Order article via Infotrieve]

29. Joffe MM, Rosenbaum PR. Invited commentary: propensity scores. Am J Epidemiol. 1999; 150: 327–333.[Abstract/Free Full Text]

30. Polterauer P, Prager M, Hölzenbein T, et al. Dacron versus polytetrafluoroethylene for Y-aortic bifurcation grafts: a six-year prospective, randomized trial. Surgery. 1992; 111: 626–633.[Medline] [Order article via Infotrieve]

31. Resnikoff M, Darling RCIII, Chang BB, et al. Fate of the excluded abdominal aortic aneurysm sac: long-term follow-up of 831 patients. J Vasc Surg. 1996; 24: 851–855.[CrossRef][Medline] [Order article via Infotrieve]

32. Huk I, Nanobashvili J, Polterauer P, et al. L-arginine treatment alters the kinetics of nitric oxide and superoxide release and reduces ischemia/reperfusion injury in skeletal muscle. Circulation. 1997; 96: 667–675.[Abstract/Free Full Text]

33. Berry AJ, Smith RBII, Weintraub WS, et al. Age versus comorbidities as risk factors for complications after elective abdominal aortic reconstructive surgery. J Vasc Surg. 2001; 33: 345–352.[CrossRef][Medline] [Order article via Infotrieve]

34. Sicard GA, Rubin BG, Sanchez LA, et al. Endoluminal graft repair for abdominal aortic aneurysms in high-risk patients and octogenarians: is it better than open repair? Ann Surg. 2001; 234: 427–437.[CrossRef][Medline] [Order article via Infotrieve]

35. Rubin DB. Estimating causal effects from large data sets using propensity scores. Ann Intern Med. 1997; 127: 757–763.[Abstract/Free Full Text]

This article has been cited by other articles:

				G S Soor, M O Chakrabarti, J R Abraham, S W Leong, I Vukin, T Lindsay, and J Butany Aortic stent grafts J. Clin. Pathol., July 1, 2008; 61(7): 794 - 801. [Abstract] [Full Text] [PDF]

				A. Wibmer, M. Schoder, K. S. Wolff, A. M. Prusa, M. Sahal, J. Lammer, I. Huk, P. Polterauer, G. Kretschmer, and H. Teufelsbauer Improved Survival After Abdominal Aortic Aneurysm Rupture by Offering Both Open and Endovascular Repair Arch Surg, June 1, 2008; 143(6): 544 - 549. [Abstract] [Full Text] [PDF]

				D. Zimpfer, H. Schima, M. Czerny, M.-T. Kasimir, S. Sandner, G. Seebacher, U. Losert, P. Simon, M. Grimm, E. Wolner, et al. Experimental Stent-Graft Treatment of Ascending Aortic Dissection Ann. Thorac. Surg., February 1, 2008; 85(2): 470 - 473. [Abstract] [Full Text] [PDF]

				H. Teufelsbauer, P. Polterauer, J. Lammer, I. Huk, J. Nanobachvili, and G. Kretschmer Repair of Abdominal Aortic Aneurysms: The Benefits of Offering Both Endovascular and Open Surgical Techniques Perspectives in Vascular Surgery and Endovascular Therapy, September 1, 2006; 18(3): 238 - 246. [Abstract] [PDF]

				M. B. Pitton, H. Schweitzer, S. Herber, W. Schmiedt, A. Neufang, P. Kalden, M. Thelen, and C. Duber MRI Versus Helical CT for Endoleak Detection After Endovascular Aneurysm Repair Am. J. Roentgenol., November 1, 2005; 185(5): 1275 - 1281. [Abstract] [Full Text] [PDF]

				A. M. Prusa, K. S. Wolff, M. Sahal, P. Polterauer, J. Lammer, G. Kretschmer, I. Huk, and H. Teufelsbauer Abdominal Aortic Aneurysms and Concomitant Diseases Requiring Surgical Intervention: Simultaneous Operation vs Staged Treatment Using Endoluminal Stent Grafting Arch Surg, July 1, 2005; 140(7): 686 - 691. [Abstract] [Full Text] [PDF]

				T. F. Lindsay and on behalf of The Canadian Society for Vascular Sur Canadian Society for Vascular Surgery consensus statement on endovascular aneurysm repair Can. Med. Assoc. J., March 29, 2005; 172(7): 867 - 868. [Full Text] [PDF]

				M. Al-Omran, S. Verma, T. F. Lindsay, R. D. Weisel, and Y. Sternbach Clinical Decision Making for Endovascular Repair of Abdominal Aortic Aneurysm Circulation, December 7, 2004; 110(23): e517 - e523. [Full Text] [PDF]

				J. T. Powell and R. M. Greenhalgh Small Abdominal Aortic Aneurysms N. Engl. J. Med., May 8, 2003; 348(19): 1895 - 1901. [Full Text] [PDF]

This Article Abstract Full Text (PDF) All Versions of this Article: 106/7/782    most recent 01.CIR.0000028603.73287.7Dv1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Teufelsbauer, H. Articles by Huk, I. Search for Related Content PubMed PubMed Citation Articles by Teufelsbauer, H. Articles by Huk, I. Related Collections CV surgery: aortic and vascular disease