COARCTATION REPAIR IN THE ADULT WITH COVERED STENTS

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1 Original Research 3 COARCTATION REPAIR IN THE ADULT WITH COVERED STENTS Sawires J 1, Guirgis M 2, BSc MD, Qadura M 2, BSc PhD MD, Saleh A 2, BSc MSc MD, Harlock JA 2, MD FRSC(C), Szalay DA 2, MD MEd FRCS(C) 1 McMaster University, Faculty of Health Sciences, Hamilton, Ontario, Canada 2 Division of Vascular Surgery, McMaster University, Hamilton, Ontario, Author for Correspondence: John Harlock MD FRCSC RPVI, Assistant Professor Division of Vascular Surgery Department of Surgery, McMaster University and Niagara Health System harlocj@mcmaster.ca Canada ABSTRACT: Coarctation of the aorta is a one of the most common congenital abnormalities diagnosed in the adult patient. Treatment of these lesions has traditionally meant open surgery, however, trans-catheter interventions, such as balloon-angioplasty and stent implantation, have now gained popularity. We present a case series of three adult patients who underwent successful treatment of aortic coarctation using covered low profile balloon expandable stents. There remains however, considerable debate regarding the best treatment option for the patients. This is in part due to the lack of high-grade evidence as well as long-term outcome data. INTRODUCTION: Coarctation of the aorta is a congenital narrowing that can occur in the descending thoracic aorta at the insertion of the ligamentum arteriosum, and accounts for 5-7% of all congenital heart diseases. 1 If left untreated, most patients die in the neonatal period; however those surviving into adulthood may develop such complications as coronary artery disease, infective endocarditis, and intracranial hemorrhage. 1 Aortic coarctation is hypothesized to result from a structural malformation during fetal development that causes greater flow through the ductus arteriosus relative to the flow entering the aorta from the left ventricle. 2 This results in the ductal flow to divide into proximal and distal streams, leading to a branch point at the distal end of the ductus arteriosis causing the obstruction. 2 Although aortic coarctation is predominantly diagnosed in infancy, cases may still be discovered later in adulthood. Given its rarity, there are no screening guidelines established and diagnosis is often made on CT imaging when investigating permissive hypertension, leg cramps, and other symptoms that are associated poor circulation to the lower extremities. 3,4 In infancy, the pre-ductal form of coarctation whereby the narrowing is proximal to the ductus arteriosis is generally seen and is associated an earlier and often more severe presentation. 2 Conversely, the post-ductal form is often seen in adulthood and has the narrowing located distal to the ductus arteriosus. 2 When diagnosed in infancy, open surgical repair is often preferred as it allows for vessel growth and has comparatively lower re-intervention rates. 5,6 Treatment of aortic coarctation in the adult patient has traditionally meant open surgical repair, involving a left thoracotomy and an end-to-end anastomosis. 7 Since the 1980s, less invasive endovascular procedures such as balloon angioplasty have proven to be an effective treatment modality promising short-term results as well as reduced mortality as compared to open repair. 8 However higher recurrence rates of up to 27% have been observed in stented

2 4 McMASTER UNIVERSITY MEDICAL JOURNAL Original Research cases. 8 Stenting of these lesions has evolved over the past ten years, initially balloon-expandable bare-metal stents and then covered stents to reduce the risk of aortic wall rupture or dissection. 8,9 The aim of this case series is to explore the postoperative outcomes of three adult patients who underwent endovascular repair of native aortic coarctation using covered stents and to add three case reports to the body of literature on this topic. METHODS: Data regarding demographics, symptoms, imaging and follow-up was collected by the authors, retrospectively, from hospital records for the three included cases. Our inclusion criteria included: patients above 18 years of age, undergoing primary coarctation repair. All three patients included were male a mean age of 33 years (range 22 40), and were treated in the same center by the same vascular surgeon. Postoperatively, each patient was followed up a CT scan at 6-8 weeks, and then yearly thereafter. Patient characteristics are summarized in Table 1. The primary measure of short-term success in the majority of available literature is a decrease in the post stent gradient of at least 20mmHg. 5,8 This pressure gradient is measured between the femoral sheath and the pigtail catheter located in the ascending aorta. However, changes in the need for antihypertensive medication postoperatively, as well as relative changes in the diameter of the coarcted segment have also been reported. 8 Additionally, re-intervention rates have also been used to assess long-term success rates. 5 CASE 1 A 40-year-old male initially presented refractory hypertension. On workup, he was found to have a 2-3mm wide post-ductal coarctation in his thoracic aorta (Figure 1). The patient had been hypertensive since his 20s, had mild asthma and was a 15- pack year smoker. Currently, despite being on four antihypertensive medications, his preoperative blood pressure (BP) was poorly controlled at 180/111 mmhg and an upper-to-lower limb pressure gradient (ULG) of 35 mmhg. Given the proximity of the coarctation to the left subclavian artery origin and the risk of blocking it a stent graft, a left subclavian to carotid bypass was planned. A spinal drain was placed preoperatively in order to manage CSF pressure and reduce the risk of spinal cord ischemia, and the patient had bilateral femoral dissections under general anesthetic. The coarctation was initially ballooned to 8mm in order to bring up the delivery system in place. Adenosine was then used to decrease the patient s heart rate during stent deployment for increased accuracy. A low profile Cook stent (Cook Inc., Bloomington, IN) was deployed across the coarct and covered the left subclavian artery. The stent measured 39mm in length. A 25mm compliant balloon (Boston Scientific, Natick, MA) was then inflated to ensure full stent deployment. (Figure 2) Finally, measurement of the left radial artery pressure demonstrated a 30 mmhg systolic drop as compared to the right and a left subclavian to carotid artery bypass was performed as planned. The patient was taken to the intensive care unit (ICU) postoperatively and discharged on postoperative day (POD) #6. The patient s blood pressure was reduced to 140/80 mmhg, and was only prescribed 2 antihypertensive medications upon discharge. Furthermore, there was a 450% fold increase in the diameter of the coarcted segment of his aorta, as well as a 35mmHg decrease in his ULG, from 35mmHg to 0mmHg. At 2-week follow-up, he the patient reported some transient weakness in his left arm. A follow-up CT showed a type 2 endoleak and an occluded left subclavian to carotid bypass, likely due to competitive flow of his large collaterals. CASE 2 A 22-year-old male no established medical history was found to be profoundly hypertensive on presentation to the emergency department after an unrelated snowboarding accident. On chest CT, a 5mm wide post-ductal coarctation was found in addition to an atrophic kidney. His preoperative blood pressure was 200/ mmhg out anti-hypertensive medication, and a ULG of 40mmHg. He was taken to the OR two days later, a spinal drain was placed preoperatively and under general anesthetic had a low profile stent (Cook Inc, Bloomington, IN) placed across his coarctation. The stent measured 39mm in length. A 25mm compliant balloon (Boston Scientific, Natick, MA) was then inflated to ensure full stent deployment. He was also taken to ICU postoperatively and was discharged POD#3 out any complications. The patient s blood pressure was reduced to 130/70 and was prescribed 2 antihypertensive medications upon discharge. The diameter of the coarcted segment increased by 260%, and his ULG decreased from 40mmHg to 5mmHg. CASE 3 A 38-year-old male a 3 year history of hypertension had been extensively worked up. A trans-thoracic echocardiogram eventually showed a narrowing in the proximal descending thoracic aorta and a follow up CT showed a 5mm post-ductal coarctation of the thoracic aorta. The patient also had a history of a bicuspid aortic valve that was repaired ten years prior. He had a preoperative blood pressure of 160/ mmhg while on 2 antihypertensive medications, and a ULG of 30 mmhg. Under local anesthetic, percutaneous access to both femoral arteries was obtained and a low profile stent (Cook Inc, Bloomington, IN) was used to dilate the coarctation to a width of 15mm. The stent measured 39mm in length. The patient developed a postoperative hematoma in his left groin and was discharged on POD#1. The patient s blood pressure was reduced to 120/80, and was prescribed only one anti-hypertensive medication. The diameter of the coarcted segment increased by 300%, and the patient s ULG decreased from 30mmHg to 0mmHg. Upon stent implementation, all three patients showed a decrease in their blood pressure, their ULG, as well as an increase in the widths of their coarctation segments. The results of each case have been summarized in Table 2. VOLUME 11 NO

3 COARCTATION REPAIR IN THE ADULT WITH COVERED STENTS 5 Patient 1 Patient 2 Patient 3 Gender Male Male Male Age Symptoms and Comorbidities Preoperative Blood Pressure control Smoker (~15 pack/year) Mild asthma control. Atrophic Kidney control. Bicuspid AV valve replaced a mechanical valve in 1996 Positive for Cardiac arrhythmias Widened QRSpacemaker History of GERD 190/ / 160/ ULG Coarctation width (mm) Preoperative medication list Angiotensin Receptor Blocker Diuretic Beta-Blocker Calcium Channel Blocker N/A Beta-Blocker Anticoagulant Figure 1. Preoperative CT scan 3D reconstruction of Patient #1 showing a post-ductal Coarctation. Table 1. Summary of preoperative patient characteristics. RESULTS Upon stent implementation, all three patients showed a decrease in their blood pressure, their ULG, as well as an increase in the widths of their coarctation segments. The results of each case have been summarized in Table 2 below. Patient 1 had a preoperative blood pressure of / while on 4 antihypertensive medications. Following endovascular stent placement his postoperative blood pressure was reduced to 140/80, and was only prescribed 2 antihypertensive medications upon discharge. Furthermore, there was a 4.5 fold increase in the diameter of the coarcted segment of his aorta, as well as a ULG decrease from 35mmHg to 0mmHg. Patient 1 was discharged POD# 6 out any complications. At 2-week follow up, he reported some transient weakness in his left arm. A follow-up CT showed a type 2 endoleak, and an occluded left subclavian to carotid bypass, likely due to competitive flow of his large collaterals Patient 2 had a preoperative blood pressure of 200/ out any antihypertensive medication, which was reduced to 130/70 postoperatively. The diameter of the coarcted segment increased by a factor of 2.6X. Additionally his ULG, decreased from 40mmHg to Figure 2. Postoperative CT scan 3D reconstruction of Patient #1 showing a patent stent graft.

4 6 McMASTER UNIVERSITY MEDICAL JOURNAL Original Research 5mmHg. Patient 2 was discharged POD# 3 out any complication. Patient 3 had a preoperative blood pressure of 160/ while on 2 antihypertensive medications, and his postoperative blood pressure was reduced to 120/80. He had a 3 fold increase in the diameter of the coarcted segment of his aorta and the patient experienced a significant decrease in his ULG as it dropped from 30mmHg to 0mmHg. Patient 3 developed a hematoma in his left groin postoperatively, and was discharged POD#1. A follow-up CT after 6 weeks confirmed stent graft patency position. Stents Patient 1 Patient 2 Patient 3 Anti-Hypertensive Medication Class Preop Postop Preop Postop Preop Postop Aorta Diameter (mm) Relative Increase in Diameter Blood Pressure Change in Gradient % 260% 300% 180/ 140/ / 130/ / Table 2. Summary of preoperative and postoperative patient characteristics. Note that PREOP refers to preoperative, and POSTOP refers to postoperative. DISCUSSION 120/ 80 Angioplasty, or out the use of covered stents is widely considered to be a viable alternative to open surgical repair, for the treatment of aortic coarctation, largely due to a high success rate, lower mortality rate and encouraging short-term results. 4,5,8,10 Pilla et al. reported technical success in 100% of their sample of 64 patients, as did Erdem et al. 47 patients and Roselli et al. 43 patients. 3,11,12 Pilla et al. also reported a 61% reduction (p < 0.001) in the prevalence of clinical symptoms identified as dizziness, visual abnormalities, headaches, fatigues, and muscle cramps in the lower limbs. 12 Furthermore, the mortality rates associated stenting are also considered low; mortality rate ranged from 0-2% in several studies, including a large multi-institutional prospective study. 3,10,12,13,14 However, the adverse effect rates associated stenting are somewhat higher; the mean rate of complications was 9% (3.4% %) 6,10,11,12,13,14,15,16 Stenting has also shown positive results in clinical outcomes including hypertension. 10,14,15,17 Mahadevan et al. report an average pre-stent systolic blood pressure of 142±14 mmhg amongst 37 patients, which dropped significantly to 125±12 mmhg in the span of a year. 14 Likewise, Macdonald et al. showed a drop in mean blood pressure from 178/93 mmhg, to 131/76 mmhg. 17 The residual blood pressure gradient has been found to be an important indicator of clinical success, and Holzer et al. established that an immediate residual gradient of less than 20 mmhg should be aimed for. 13 In all cases, stenting has been shown to decrease the blood pressure gradient well past the 20 mmhg target; the residual blood pressure gradient decreased by an average of 34.2 mmhg ( mmhg) across 279 patients. 11,12,14,15,16,17,18,19 Our group of three patients all had successful endovascular treatment of their aortic coarctation using covered stents. All three saw a reduction in their ULG of at least 30 mmhg and at least a 2.5 fold increase in the aortic diameter following treatment of the coarcted segment. Furthermore, these patients saw a significant change between their pre- and postoperative blood pressure as well as the number of anti-hypertensive medications prescribed. Our success and complication rates are comparable to those described in the literature; all three patients had their stents successfully implanted, and achieved a 20 mmhg reduction in ULG. Furthermore, the only complication was seen in patient 3, in which a hematoma developed postoperatively in his left groin. In comparison to surgery and Balloon angioplasty, stenting appears to be a viable alternative. With regards to morbidity, stenting was shown to have lower rates when compared to balloon angioplasty. 6,12 Paradoxically, surgery is considered a safer treatment; Carr et al. hypothesize this is because although complications from open surgery may be slightly more frequent, complications seen in stenting are likely to be more severe. 6 The most common postoperative complications for the surgical treatment of aortic coarctation appear to be the development of hypertension, recurrent coarction, and aortic aneurysm.1 Complications for endovascular treatment of aortic coarctation can be arranged in three categories: the first category being aortic wall complications, which includes intimal tears, aortic wall dissections, and aortic aneurysms; the second category being technical complications, which includes stent displacement, stent fracture, and balloon rupture; and lastly the third category being vascular complications, which includes cerebrovascular accident, peripheral embolic event, injury to access vessels, hematoma formation, and bleeding. 16 In terms of efficacy, Tanous et al. advocate the use of stenting over angioplasty in nearly all cases of native coarctation, whereas Carr et al. publish that surgery consistently cures >60% of patients hypertension, whereas stenting cures 40-60%. 6,10 However, Lam et al. found surgery is often associated loss of right ventricle functionality, as surgery patients show significantly lower free wall systolic velocities than their stenting counter-parts. 18 Lastly, the need for re-intervention is much higher in endovascular repair (including both stenting and angioplasty) than open surgery, and although the costs of surgery are higher in comparison, the extensive need for reintervention results in stenting being a less cost-effective treatment. 6 SUMMARY Native aortic coarctation remains one of the most common congenital heart anomalies seen in the adult patient. Endovascular treatment is a viable alternative to surgery in the treatment of these coarcted segments. Some of the current literature demonstrates a high success VOLUME 11 NO

5 COARCTATION REPAIR IN THE ADULT WITH COVERED STENTS 7 rate, lower mortality and encouraging short-term results. However, the majority of this data is based on single center cases-controlled studies. There remains a lack of long-term follow up data to support these claims. References 1. Chen M, Shih P, Tholpady A, Kramer C, et al. Surgical and endovascular repair of aortic coarctation: Normal findings and appearance of complications on CT angiography and MR angiography. Am J Roentgenol 2006; 187: pp. W302-W Hutchins GM. Coarctation of the aorta explained as a branch-point of the ductus arteriosus. Am J Pathol 1971; 63(2): pp Roselli EE, Qureshi A, Idrees J, et al. Open, hybrid, and endovascular treatment for aortic coarctation and postrepair aneurysm in adolescents and adults. Ann Thorac Surg 2012; 94: pp Koletsis E, Ekonomidis S, Panagopoulos N, et al. Two stage hybrid approach for complex aortic coarctation repair. J Cardiothorac Surg 2009; 4(10): pp Zabal C, Attie F, Rosas M, et al. The adult patient native coarctation of the aorta: balloon angioplasty or primary stenting? Br Med J 2003; 89: pp Mahadevan VS, Vondermuhll IF, Mullen MJ. Endovascular aortic coarctation stenting in adolescents and adults: angiographic and hemodynamic outcomes. Catheter Cardiovasc Interv 2006; 67(2): pp Tanous D, Collins N, Dehghani P, et al. Covered stents in the management of coarctation of the aorta in the adult: initial results and 1-year angiographic and hemodynamic follow-up. Int J Cardiol 2010; 140(3): pp Yildirim I, Karagoz T, Sahin M, et al. Endovascular stents for treatment of coarctation of the aorta. Anadolu Kardioyol Derg 2011; 11(4): pp Macdonald S, Thomas SM, Cleveland TJ, et al. Angioplasty or stenting in adult coarctation of the aorta? A retrospective single center analysis over a decade. Cardiovasc Intervent Radiol 2003; 26(4): pp Lam YY, Kaya MG, Li W, et al. Effect of endovascular stenting of aortic coarctation on biventricular function in adults. Heart 2007; 93(11): pp Shennib H, Rodriguez-Lopez J, Ramaiah V, et al. Endovascular management of adult coarctation and its complications: intermediate results in a cohort of 22 patients. Eur J Cardiothorac Surg 2010; 37(2): pp Carr JA. The results of catheter-based therapy compared surgical repair of adult aortic coarctation. J Am Coll of Cardiol 2006; 47(6): pp Palma G, Giordano R, Russolillo V, et al. in adult after operation of aortic coarctation. J Cardiovasc Surg 2011; 52: pp Egan M, Holzer RJ. Comparing balloon angioplasty, stenting and surgery in the treatment of aoric coarctation. Expert Rev Cardiovasc Ther 2009; 7(11): pp Ringel RE, Gauvreau K, Moses H, et al. Coarcation of the aorta stent trial (COAST): Study design and rationale. Am Heart J 2012; 164(1): pp Tanous D, Benson LN, Horlick EM. Coarctation of the aorta: evaluation and management. Curr Opin Cardiol 2009; 24(6): pp Erdem A, Akdeniz C, Saritas T, et al. Cheatham-Platinum stent for native and recurrent aortic coarctation in children and adults: immediate and early follow-up results. Anadolu Kardiyol Derg 2011; 11(5): pp Pilla CB, Fontes VF, Pedra CA. Endovascular stenting for aortic coarctation. Expert Rev Cardiovasc Ther 2005; 3(5): pp Holzer R, Qureshi S, Ghasemi A, et al. Stenting of aortic coarctation: acute, intermediate, and long-term results of a prospective multi-institutional registry--congenital Cardiovascular Interventional Study Consortium (CCISC). Catheter Cardiovasc Interv 2010; 76(4): pp At the Michael G. DeGroote School of Medicine, our international reputation for teaching and research innovation is putting Hamilton on the world map. Researchers at Canada s McMaster University have figured out how to make blood out of human skin...patients needing blood will be able to have blood created from a patch of their own skin. CNN McMaster is the birthplace of problem-based learning so successful that when Harvard medical school adopted a PBL approach it was hailed as the new pathway for medical education. Newsweek