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Ann Thorac Surg 2006;82:2147-2153
© 2006 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Long-Term Results From a 12-Year Experience With Endovascular Therapy for Thoracic Aortic Disease

^a Department of Surgery, University of Michigan Hospitals, Ann Arbor, Michigan
^b Department of Radiology, University of Michigan Hospitals, Ann Arbor, Michigan

Accepted for publication June 19, 2006.

^_* Address correspondence to Dr Patel, Department of Surgery, Section of Cardiac Surgery, 2120 Taubman Center Box 0348, 1500 E. Medical Center Dr, Ann Arbor, MI 48109-0348 (Email: hjpatel{at}med.umich.edu).

Presented at the Poster Session of the Forty-second Annual Meeting of The Society of Thoracic Surgeons, Chicago, IL, Jan 30–Feb 1, 2006.

Dr Williams discloses that he has a financial relationship with Medtronic and Gore; Drs Deeb and Dasika with Cook, Gore, and Medtronic.

 

	Abstract

Top Abstract Introduction Patients and Methods Results Comment References

 
BACKGROUND: Endovascular approaches promise to revolutionize therapy for thoracic aortic disease. This study describes a long-term analysis of endovascular thoracic aortic repair.

METHODS: Seventy-three patients (mean age, 67.4 years) underwent endovascular thoracic aortic repair from 1993 to 2005. Indications for intervention included aneurysm (38%), dissection (23%), or penetrating ulcer or pseudoaneurysm (34%). Rupture was present in 16 patients (22%). Seventy-one percent were considered high risk for open surgery for reasons of age or comorbid conditions. Treated segments included ascending aorta (n = 1), distal arch (n = 24), and proximal (n = 50) or distal (n = 55) descending aorta. The total descending thoracic aorta was covered in 31 patients. Procedural success was achieved in 96%. Devices were delivered by femoral (79%), retroperitoneal iliac (18%), or carotid (2.7%) exposure. Devices used included Excluder (n = 30), Talent (n = 23), Zenith (n = 3), AneuRx (n = 5), and custom-fabricated (n = 14). Follow-up was 100% complete.

RESULTS: Thirty-day mortality was 5.5%. Significant morbidity included stroke (8.2%) and need for dialysis (4.1%). Although 3 patients had transient spinal cord ischemia (4.1%), none had permanent sequelae. Intervention for fusiform aneurysm was independently associated with a composite end point of 30-day mortality, need for dialysis, and stroke (p = 0.015). Eight patients (11%) had new or persistent endoleaks, and aortic reintervention was performed in 7 patients (9.6%). Mean survival for the entire cohort was 46.8 ± 5.1 months. Intervention for penetrating ulcer or pseudoaneurysm (p = 0.045) was independently associated with long-term all-cause mortality.

CONCLUSIONS: An endovascular approach produces acceptable results for a broad range of thoracic aortic disease. However, the potential for endoleak or need for reintervention mandates continued close follow-up to achieve satisfactory long-term results.

The report by Parodi and colleagues [1] of successful endoluminal abdominal aortic repair (EVAR) in 1991 ushered in the era of minimally invasive approaches for aortic disease. After the seminal report by Dake and associates [2] describing endovascular thoracic aortic repair (TEVAR), several investigators reported early to mid-term results with TEVAR [3–9]. In contrast to EVAR (typically performed for aneurysms), TEVAR has been applied for a variety of pathologic entities including aneurysms, acute aortic syndromes (penetrating ulcers, intramural hematomas, aortic dissections), aortobronchial fistulas, and traumatic aortic disruptions [2–9].

The benefits of TEVAR obviate the significant morbidity and mortality encountered with traditional open surgery [10,11]. Despite the excellent results reported with open repair, there is a perceived lower morbidity with an endovascular approach. Benefits of open repair include the very durable nature of the operation with an extremely low rate for reintervention in the treated aortic segment(s) [10]. In contrast, prior reports of endovascular repair show that there is a significant endoleak rate and need for reintervention [6,8].

This report describes both procedural and late outcomes with an initial 12-year experience with TEVAR. Endovascular thoracic aortic repair in this study was used for a broad spectrum of thoracic aortic disease.

	Patients and Methods

Top Abstract Introduction Patients and Methods Results Comment References

 
Data from all patients undergoing TEVAR at the University of Michigan Hospitals between 1993 and 2005 (n = 73, 60.3% male) were retrospectively analyzed. This study was approved by the Institutional Review Board of the University of Michigan Hospitals (No. 2003–0128; informed consent requirements waived).

Thoracic surgeons experienced in aortic reconstruction performed the initial preoperative evaluation. Suitability of the aortic lesion for TEVAR was based on patient comorbidities, characteristics of available devices, anatomic features of the lesion, and quality of access vessels. This assessment was made collaboratively by surgery and interventional radiology. The surgical team (either thoracic or vascular) was primarily responsible for obtaining access and directing postoperative care, whereas device sizing and delivery were done collaboratively by surgeons and radiologists. Sizing for TEVAR was performed using spiral computed tomography with or without three-dimensional reconstruction, intravascular ultrasound, or calibrated angiography. Operative procedures were performed either in the operating room with fluoroscopy or in an angiography suite with fixed imaging equipment. General anesthesia was used in all except 1 patient (with poor pulmonary function), who was treated in the semi-seated position using local anesthesia. Percutaneous access to obtain necessary angiograms was obtained through either the brachial or contralateral femoral artery. Patients were administered systemic heparin to maintain activated clotting times greater than 250 seconds. The activated clotting time was checked at 30-minute intervals, and heparin was readministered as guided by the activated clotting time. The access vessel was isolated for device delivery. Device positioning and deployment were guided by angiographic landmarks or intravascular ultrasound. Completion aortography was performed, and all type I or type III endoleaks were treated when identified. All catheters were then withdrawn. The access vessel was then repaired, and protamine was administered to reverse the anticoagulation.

Postoperative management for prevention of spinal cord ischemia was conducted according to standardized protocols described as follows. Lumbar drainage was used selectively at the discretion of the operating surgeon in 10 patients (13.5%), and all lumbar drains were placed just after induction of anesthesia. No significant complications identified were directly attributed to lumbar drain placement. All patients were managed with mild permissive hypertension postoperatively to keep spinal perfusion pressures at 80 mm Hg or higher (if a lumbar drain was placed), or a mean arterial pressure of 90 to 100 mm Hg (if no lumbar drain was present). Duration of lumbar drainage was generally 24 to 36 hours. At that time, if no neurologic sequelae had occurred and the patient was hemodynamically stable, the drain was capped for an additional 6 to 8 hours before removal.

Data were collected from clinic visit notes, hospital charts, imaging studies, and interrogation of the National Death Index. Follow-up was 100% complete as of February 2006. The median length of follow-up was 22.5 months (mean, 30.2 ± 29.6 months).

Statistical Analysis
Early outcomes included 30-day or in-hospital mortality, stroke, permanent renal failure, and permanent paralysis or paresis. Late outcomes included presence of new or persistent endoleak, need for aortic reintervention, and vital status.

Data were analyzed using SAS V8.2 (SAS, Cary, NC). Dichotomous variables were evaluated using ² analysis; continuous variables using one-way analysis of variance. Multivariate models (logistic regression for dichotomous variables and linear regression for continuous variables) were constructed using a forward selection process to identify factors that were independently associated with each of the outcomes of interest. Survival analysis and freedom from reintervention were analyzed by life table methods. All results with probability less than 0.05 were considered statistically significant.

	Results

Top Abstract Introduction Patients and Methods Results Comment References

 
Preoperative demographics, comorbidities, and indications for intervention are listed in Table 1. Reasons for proceeding with TEVAR versus open repair included the following. The most frequent reason was the consideration by an experienced thoracic aortic surgeon that the patient was high risk for open surgery (52 patients, 71.2%) on the basis of age of 80 years or older (n = 18, 24.7%) or significant comorbid conditions (n = 51, 69.9%; Table 2). "Anatomic" reasons, such as presentation with a saccular aneurysm or short-segment fusiform aneurysm, that appeared quite feasible with an endovascular approach were present in 22 patients (30.1%). Finally, patient preference for TEVAR was a reason in 18 patients (24.7%).

Details regarding both TEVAR and additional procedures performed at the time of intervention are listed in Table 3. Extension of the proximal landing zone by either partial or complete left subclavian arterial coverage was required in 16 patients (21.9%). Three patients had prior left carotid to left subclavian artery bypass grafting, whereas 2 patients had postoperative procedures for arm ischemia from subclavian coverage (1 requiring bypass in the seventh postoperative month, and 1 treated with a subclavian artery stent hours after TEVAR).

Permanent spinal cord ischemia was not observed in any patient. In contrast, cord ischemia causing temporary paralysis was diagnosed in 3 patients, all within 48 hours of the intervention. A lumbar drain was inserted in all 3 with immediate complete resolution in 2 patients. The third patient had total return of lower extremity function by discharge, and resolution of bowel and bladder dysfunction by the first postoperative visit. A preoperative history of peripheral vascular disease, total number of stent grafts used, and type of additional in-hospital procedure were all univariate correlates of temporary paralysis (all p < 0.05). Although all 3 patients who had transient paralysis had the entire descending thoracic aorta covered, the need for total descending thoracic aortic coverage only approached statistical significance (p = 0.06), likely owing to small sample size. In contrast to other reports, a previous history of abdominal aortic aneurysm repair (13 patients) did not correlate with the occurrence of spinal cord ischemia (p = 0.41) [8].

Postoperative dialysis was required in 3 patients (4.1%). New-onset renal failure (defined as a rise in postoperative creatinine at any time to 2.0 mg/dL) was identified in 9 patients (12.3%). The mean preoperative and discharge creatinine levels were 1.4 ± 1.8 mg/dL and 1.3 ± 1.1 mg/dL, respectively. By univariate analysis, a prior history of peripheral vascular occlusive disease or other concomitant aneurysms, presentation with a rupture, type of stent graft used, need for aortic coverage into the visceral segment, and type of additional in-hospital procedure all correlated with the need for postoperative dialysis (all p < 0.05).

A composite end point of postoperative mortality, stroke, or need for hemodialysis was constructed. By univariate analysis, reoperation for access-related bleeding complications or the occurrence of a new endoleak, rupture, or dissection in treated or adjacent aortic segments correlated with the composite end point (all p < 0.05). A multivariate analysis of age, date of initial intervention, preoperative comorbidities, and aortic disease demonstrated that only a diagnosis of fusiform aneurysm independently predicted the composite end point (odds ratio, 24.0; p = 0.015).

Long-Term Results
Overall survival for the entire cohort was 59.4%. By life table analysis, mean survival was 46.8 ± 5.1 months (Fig 1; median survival, 4.2 years). Univariate analysis demonstrated the type of endograft used (custom-fabricated versus commercially available), the aortic pathologic indication for intervention, and the occurrence of postoperative renal failure were all correlated with long-term mortality (all p < 0.05). By multivariate analysis of factors including age, date of initial intervention, preoperative comorbidities, and aortic disease, only intervention for either penetrating ulcer or pseudoaneurysm independently predicted a lower long-term risk for mortality (odds ratio, 0.072; p = 0.045).

View larger version (15K): [in this window] [in a new window]   Fig 1. Long-term survival after endovascular thoracic aortic repair. All-cause mortality for the entire cohort was 40.5%. Five-year survival by life table analysis is 35%, likely reflecting the high-risk status of the study group. The solid line represents the survival curve and the dashed lines are the 95% confidence limits.

View larger version (47K): [in this window] [in a new window]   Fig 2. Eventual outcome after initial endovascular thoracic aortic repair. In this cohort, in which approximately 75% were considered high risk for open surgery, almost 50% of patients are alive without reintervention at last follow-up.

View larger version (15K): [in this window] [in a new window]   Fig 3. Life table analysis of freedom from aortic reintervention. Freedom from aortic reintervention was 81.2% at 5 years, with the mean time to reintervention of 31.6 ± 1.8 months. The solid line represents the survival curve and the dashed lines are the 95% confidence limits.

View larger version (18K): [in this window] [in a new window]   Fig 4. Life table analysis of freedom from open surgery or aneurysm-related mortality. Freedom from open surgery or aneurysm-related death was 79% at 5 years, with a mean time to occurrence of the event of 48.1 ± 2.3 months. The solid line represents the survival curve and the dashed lines are the 95% confidence limits.

	Comment

Top Abstract Introduction Patients and Methods Results Comment References

Our initial 12-year experience described here demonstrates that satisfactory perioperative results can be achieved with TEVAR for a wide variety of pathologic entities. In this "learning curve" series, 71% of patients were considered high risk for conventional open approaches after evaluation by thoracic surgeons experienced in thoracic aortic reconstruction. In addition, 29% presented either with rupture or with pathologic entities (aortobronchial fistulas, mycotic aneurysms, acute dissection) traditionally considered high-risk operative procedures.

Prior reports have also documented the safety and feasibility of TEVAR in both low-risk and high-risk settings [2–9]. The multicenter phase II trial of the Gore TAG endoprosthesis (performed in acceptable surgical candidates) documented a mortality rate of 1.5% along with a 7% incidence of neurologic events (4% stroke, 3% transient or permanent paralysis) [4]. Similar results have been demonstrated in institutional series, as well as the combined EUROSTAR/United Kingdom Thoracic Registries [5–9].

Despite improving results, adverse neurologic events after either open or endovascular thoracic aortic repair remain the focus of continued concern [2–11]. Reported outcomes of TEVAR focus on the proposed decrease in postoperative paralysis [2–5]. Although this approach likely minimizes hemodynamic instability, the need to cover more thoracic aorta (for landing zone fixation) as well as the inability to reimplant critical intercostal vessels may limit the benefit of TEVAR with regard to spinal cord ischemia. Endovascular thoracic aortic repair also introduces new challenges with respect to the postoperative complication of stroke, a relatively underemphasized complication of endovascular therapy. Device delivery in TEVAR mandates manipulation of large-bore sheaths and stiff guidewires through heavily diseased segments of both arch and descending aorta, thereby increasing the risk for atheroembolism. In this study, three of the six strokes were diagnosed at emergence from anesthesia, suggesting that a frequent cause of this complication is atheroembolism during device deployment. Improvements in device design or delivery mechanisms, such as hydrophilic sheaths with precurved shapes (similar to the arch contour), may decrease this complication.

Although early success of TEVAR has been demonstrated, the question of durability remains unanswered. Traditional open repair is exceedingly secure, with a low failure rate in treated aortic segments [10]. In contrast, post-TEVAR endoleak can predispose treated patients to aneurysm-related mortality [8]. Both abdominal and thoracic aortic endovascular repair have an overall endoleak rate of 10% to 25%, which may be device-specific [2–9, 12]. However, endoleaks after TEVAR are frequently the more virulent type I (proximal or distal attachment zone) or type III (junctional) varieties [8]. In contrast, post-EVAR endoleaks are more often type II endoleaks (backflow from aortic side branches), which may portend a better prognosis [8,14]. If needed, however, additional procedures to treat endoleaks can also be performed with an endoluminal strategy (Fig 3 versus Fig 4).

Aortic disease may also determine TEVAR durability [5]. Dilatation of the proximal neck after open infrarenal aortic aneurysmectomy has been demonstrated previously [13]. This occurrence may vary in thoracic aortic aneurysmal disease depending on the initial disease. A neck in fusiform aneurysmal disease may behave differently than that in aortic dissection, or traumatic injury. The large EUROSTAR/United Kingdom registry has demonstrated differences in outcomes according to the aortic disease [5]. In our study, we failed to identify a correlation between aortic disease and the success rate of the initial endograft procedure, likely because of the sample size. However, we have noted late adjacent aortic problems in all 4 patients who underwent attempts at stent graft placement to cover only a penetrating ulcer when the ulcer was associated with intramural hematoma. Three of these patients presented within a year with pseudoaneurysm formation at the landing zone(s), and the fourth ruptured the descending thoracic aorta on the night of the operation. These results underscore the absolute necessity to fixate the device in healthy aorta both proximally and distally to avoid long-term failure of TEVAR.

The acceptable periprocedural and long-term success rates demonstrated here suggest that the primary mode of therapy in the high-risk patient should be an endovascular approach. Since the approval by the US Food and Drug Administration of the first thoracic endograft, our current approach for the patient with descending thoracic aortic disease is to offer either an open or endovascular repair to those both anatomically and physiologically suitable for both types of therapy. For those patients with a good life expectancy (eg, 50 to 70 years with minimal comorbid conditions), our preference, however, is an open approach, given its demonstrated long-term durability. For those patients with suspected limited life expectancy (eg, age older than 70 years or significant comorbid conditions making open repair a higher risk), our preference is an endovascular approach, given its relatively lower morbidity and mortality.

In conclusion, this report demonstrates that an endovascular approach can be performed with acceptable early morbidity and mortality for a broad spectrum of thoracic aortic disease. However, the development of a new or persistent endoleak, or recurrent disease in either treated or adjacent aortic segments in the long-term, mandates continued close follow-up to prevent thoracic aortic aneurysm-related mortality. Finally, this series describing outcomes from an initial endovascular approach presents an encouraging picture of the potential for this new technology.

	References

Top Abstract Introduction Patients and Methods Results Comment References

 

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11. Coselli JS, LeMaire SA, Koksy C, et al. Left heart bypass during descending thoracic aortic aneurysm repair does no reduce the incidence of paraplegia Ann Thorac Surg 2004;77:1298-1303.[Abstract/Free Full Text]
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This Article Abstract Full Text (PDF) 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 Add to Personal Folders Download to citation manager Author home page(s): Himanshu J. Patel Mary C. Proctor G. Michael Deeb Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Patel, H. J. Articles by Deeb, G. M. Search for Related Content PubMed PubMed Citation Articles by Patel, H. J. Articles by Deeb, G. M. Related Collections Great vessels