Thoracic endovascular aneurysm repair for complicated type B aortic dissection

Jan D. Blankensteijn, MD, PhD, Section Editor EVIDENCE SUMMARY Thoracic endovascular aneurysm repair for complicated type B aortic dissection Christoph A. Nienaber, PhD, MD, a Stephan Kische, MD, a Hüseyin Ince, PhD, MD, a and Rossella Fattori, PhD, MD, b Rostock, Germany; and Bologna, Italy Endovascular reconstruction of the true lumen by use of minimally invasive stent grafting or stenting is becoming increasingly popular and may have the potential to emerge as the first-line therapy for acute complicated type B dissection. Thoracic aortic dissection can be classified as complicated vs uncomplicated (stable), or anatomically according to the origin of the intimal tear or whether the dissection involves the ascending aorta. Although the outcomes of so-called complicated type B dissection are known to be disastrous with open surgery and disappointing with medical management alone, those patients with complications, such as organ malperfusion syndrome, impending rupture, ongoing pain, and resistant hypertension, may qualify preferentially for endovascular reconstruction of the true lumen. Cumulative extraction of currently available outcomes data and meta-analytic interpretation of the available observational evidence suggest that endovascular stent grafts provide improved survival in the setting of complicated type B dissection today. (J Vasc Surg 2011;54:1529-33.) Endovascular reconstruction of the true lumen by use of minimally invasive stent grafting or stenting is becoming increasingly popular and may have the potential to emerge as the first-line therapy for acute complicated aortic dissection. Acute thoracic aortic dissection can be classified as complicated vs uncomplicated (stable), or anatomically, according to the origin of the intimal tear or whether the dissection involves the ascending aorta, regardless of the site of origin. Accurate classification is important because it drives decisions regarding surgical vs nonsurgical management. The most common classification schemes are the De- Bakey and the Stanford systems (Fig 1). The ascending aorta refers to the aorta proximal to the brachiocephalic artery, and the descending aorta is distal to the left subclavian artery. Although dissection of the ascending aorta requires immediate surgical attention, therapeutic strategies to the descending aorta in case of type B dissection may From the Heart Center, University of Rostock, Rostock a ; and the Department of Radiology and Cardiovascular Imaging Unit, University of Bologna, Bologna. b Competition of interest: none. Correspondence: Christoph A. Nienaber, MD, FESC, FACC, Heart Center and Department of Internal Medicine, University of Rostock, Ernst- Heydemann-Str 6, 18055 Rostock, Germany (e-mail: christoph.nienaber@ med.uni-rostock.de). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a competition of interest. 0741-5214/$36.00 Copyright 2011 by the Society for Vascular Surgery. doi:10.1016/j.jvs.2011.06.099 vary. Endovascular stent graft placement may be technically feasible and relatively safe as a procedure but may not always be prognostically beneficial. For instance, the risk of death in type B aortic dissection is increased in patients who present with or develop complications such as retrograde dissection or any kind of organ or limb malperfusion. 1-4 Other predictors of increased inhospital death include age 70 years, hypotension or cardiac tamponade, kidney failure, and pulse deficits. 5 Although patients with uncomplicated type B dissection have a 30-day mortality of 10%, 6 those with ischemic complications, such as renal failure, visceral ischemia, or contained rupture, often require urgent aortic repair, which carries a mortality of 20% by day 2 and 25% by day 30. Moreover, similar to type A dissection, advanced age, rupture, shock, and malperfusion are important independent predictors of early death in type B dissection. 7-9 METHODS The intent of the current review was to identify rates of mortality and morbidity associated with various treatment modalities of type B aortic dissection. Data were extracted from a search of peer-reviewed literature until December 2010. With search criteria comprising endovascular repair, medical treatment, and surgical repair, the outcomes of 17,000 patients with reported type B aortic dissection in a variety of clinical presentations were analyzed, including acute, subacute, and chronic, as well as uncomplicated and complicated dissection. Even with differing follow-up periods reported in the extracted publications, reports were adjusted and homogenized to 1529

1530 Nienaber et al JOURNAL OF VASCULAR SURGERY November 2011 Fig 1. DeBakey and Stanford classifications of aortic dissection. Table I. Primary outcome after stent graft intervention for type B dissection No. Primary technical success rate (%) Range (%) All type B dissections 3092 95.1 79-100 Acute Complicated 1052 95.6 84-100 Uncomplicated 17 100... Subacute Complicated 54 100... Uncomplicated 72 95.7... Chronic Complicated 849 90.2 83-100 Uncomplicated 89 93.8... 1 year, 2 years, and long-term follow-up. Standardized definitions (as used in those publications) for group allocation were applied. RESULTS On aggregate, acute aortic pathology confined to the descending aorta usually remains subject to medical treatment, unless complicated by organ or limb malperfusion, progressive dissection, extra-aortic blood collection (impending rupture), intractable pain, or uncontrolled hypertension. 10 In these scenarios, endovascular interventions come into play with a primary technical success rate of 90% on average (Table I) and with increasingly convincing evidence for improved outcomes compared with open surgery or medical treatment alone. More than 80% of patients with complicated acute or chronic type B dissection are likely to survive for 1 and 2 years if they undergo timely endovascular reconstruction (Table II). Interestingly, when monitored over time, it becomes evident that 20% require some reintervention after 1 year, with growing need for adjunctive interventions after 2 years and at long-term (Table III). Care for pathology of the descending aorta. Traditionally, open surgical replacement of the diseased aorta has been performed through a left posterolateral thoracotomy, with prosthetic graft replacement of the descending thoracic aorta, in conjunction with singlelung ventilation, full heparinization, cardiopulmonary bypass, profound hypothermia, cerebrospinal fluid drainage, and circulatory arrest, in an attempt to minimize morbidity, particularly stroke and paraplegia. 6,26 Data from the International Registry of Acute Aortic Dissection database suggest an improving but significant mortality rate for emergency complicated type B dissections during the last 5 years, with contemporary in-hospital mortality rates of 17% reported with open surgery. 27 Given the reasonable results with medical management for uncomplicated type B dissections, medical therapy constitutes a gold standard that is difficult to surpass with surgery. Historically, patients who undergo surgical treatment of type B dissections have had a mortality rate of 10.7%. 28 In the emergency setting, 25% to 50% of patients have persistent false-lumen flow, and surgeons have had variable success in relieving distal malperfusion.

JOURNAL OF VASCULAR SURGERY Volume 54, Number 5 Nienaber et al 1531 Table II. Survival rates after stent graft interventions in type B aortic dissection Survival, % First author 1 year 2 years Eggebrecht 11 Overall complicated 80.4 6.7 73.2 7.8 Alves 12 Overall complicated 80 80 Böckler 13 Overall complicated 80.4 5.6 72.3 6.7 Chaikof 14 Overall complicated 73... Kische 15 Overall complicated 90.6 2.3 90.6 2.3 Shimono 16 Chronic complicated 100 100 Böckler 17 Chronic complicated 100 90 Jing 18 Chronic complicated... 92.3 Sayer 19 Chronic complicated... 66.5 Böckler 17 Acute complicated 62 62 Jingl 18 Acute complicated... 86.4 Sayer et al 19 Acute complicated... 93 Verhoye 20 Acute complicated 73 11 73 11 Cambria 21 Acute complicated 79... Ehrlich 22 Acute complicated 81 78 Steuer 23 Acute complicated 94... Zeeshan 24 Acute complicated 82 79 Eggebrecht 25 Meta-analysis 89.9 1.7 88.8 1.9 Table III. Freedom from reintervention after stent graft placement First author 1 year (%) 2 years (%) Long-term (%) (years) Böckler 17 Overall complicated 81 73 68 5 Kische 15 Overall complicated...... 71.5 3 Jing 18 Chronic complicated...... 96 4 Sayer 19 Chronic complicated... 55...... Jing 18 Acute complicated...... 74 4 Sayer 19 Acute complicated... 62...... Ehrlich 22 Acute complicated 78... 61 4 The risk of irreversible spinal cord injury and operative death for acute type B dissections can range from 14% to 67%. 7,27 Endovascular repair. Endovascular repair is developing as a strong alternative to surgery and may eventually evolve as a superior method for definitive treatment for patients with appropriate indications (complicated dissections). Intuitive advantages include the ability to obliterate the false lumen by sealing the aortic tear with an aortic endograft, thereby repressurizing the collapsed true lumen and abolishing any distal malperfusion. Among patients with acute type B aortic dissection, false lumen rupture causes 60% of associated deaths. Continued patency of the false lumen has been reported to lead to aneurysmal dilatation; but even if only partial thrombosis of the false lumen is achieved, the endograft may still protect the false lumen from enlarging over time. 29 DISCUSSION The feasibility of stent grafting for dissections of the descending thoracic aorta has been well established since the late 1990s as a supplemental treatment and an alternative to classic high-risk surgical treatment; however, because there are no randomized trials involving complicated type B dissection with substantial follow-up, indications for stent grafting are not firmly settled yet. Observational evidence shows that depressurization and shrinkage of the false lumen are beneficial in acute type B aortic dissections, with the goal of thrombosis of the false lumen and remodeling of the dissected aorta. Similar to previously accepted indications for surgical intervention, refractory pain, malperfusion, expansion 1 cm/year, and a critical diameter of 5.5 cm are increasingly being accepted as indications for stent graft placement in type B aortic dissections. Stent placement has been used to treat retrograde extension of a type B dissection into the ascending aorta because coverage of the entry site may enable thrombosis, remodeling of the false lumen, and even healing. If malperfusion of a branch vessel persists, branch vessel stenting or the technique of provisional extension to induce complete attachment (PETTICOAT) may be used with open bare-metal stents to correct distal malperfusion (Fig 2, a-d). 30 Patients who present with unstable type B aortic dissection manifesting renal or mesenteric ischemia have an operative mortality rate of 50% and 88%, respectively. 31,32 Early data from the IRAD registry of aortic dissections suggested significant differences with respect to in-hospital death stratified by type of treatment for patients with acute type B aortic dissections. IRAD reported an in-hospital mortality rate of 32% for surgically treated individuals, 7% for those managed with endovascular techniques, and 10% for those managed with medical therapy alone (P.0001). 27,33 These results have been confirmed by subsequent studies. Interestingly, of 571 patients with acute type B aortic dissection in IRAD, 390 (68%) were treated medically; among complicated cases, 59 (10%) underwent standard open surgery, and 66 (12%) were

1532 Nienaber et al JOURNAL OF VASCULAR SURGERY November 2011 Fig 2. Malperfusion syndrome treated with endovascular stent graft and the provisional extension to induce complete attachment (PETTICOAT) technique. a, Angiography of lower body shows malperfusion. b, Angiography shows reperfusion after proximal stent graft placement. c, Three-dimensional computed tomography reconstruction shows acute complicated dissection with malperfusion. d, Reconstructed aorta and abolished malperfusion are shown after stent graft and PETTICOAT technique. with appropriate use of endovascular stent graft placement, patients with complicated dissection enjoyed an improved prognosis, eventually similar to patients with an uncomplicated stable course requiring only medical management. Conversely, with propensity and multivariable adjustment, open surgical repair was associated with an increased risk of in-hospital death (odds ratio, 3.41; 95% confidence interval, 1.00-11.67; P.05). Fig 3. Comparison of various treatments in patients with complicated acute type B aortic dissections. 34 treated by endovascular techniques (even in 40% after open surgical repair). 34 The in-hospital mortality rate of patients with complicated type B dissection was significantly higher after open surgery (33%) than after endovascular treatment (11%; Fig 3). This demonstrated that CONCLUSIONS Thus, although long-term data are not available, stent graft repair is emerging as an attractive alternative to open surgical repair for dissection with ischemic complications or impending rupture. The meta-analysis of outcomes for endovascular treatment of acute type B aortic dissections revealed an in-hospital mortality rate of 9%. Major complications included stroke, 3.1%; paraplegia, 1.9%; conversion to type A dissection, 2%; bowel infarction, 0.9%; and major amputation, 0.2%. Aortic rupture occurred in 0.8% during a 20-month period. The meta-analytic approach to the available body of observational evidence indicates that endovascular treatment of complicated acute type B aortic dissection enables favorable initial outcomes and improved survival. Although data on long-term outcomes are required, endovascular reconstruction provides an important treatment option today. 32

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Submitted May 7, 2011; accepted Jun 25, 2011.