Tese
“DOS CONVENCIONAIS AOS RECOBERTOS”: 15 ANOS DE
EXPERIÊNCIA DE UM CENTRO TERCIÁRIO NO TRATAMENTO
PERCUTÂNEO DA COARCTAÇÃO DE AORTA COM STENTS
João Luiz Langer Manica
FUNDAÇÃO UNIVERSITÁRIA DE CARDIOLOGIA
Programa de Pós-Graduação em Medicina: Área de Concentração: Cardiologia e
Ciências da Saúde
“DOS CONVENCIONAIS AOS RECOBERTOS”: 15 ANOS DE
EXPERIÊNCIA DE UM CENTRO TERCIÁRIO NO TRATAMENTO
PERCUTÂNEO DA COARCTAÇÃO DE AORTA COM STENTS
Autor: João Luiz Langer Manica
Orientador: Prof. Dr. Rogério Sarmento Leite
Co-Orientador: Prof. Dr. Raul Ivo Rossi Filho
Orientador estrangeiro: Prof. Dr. Mario Carminati
Co-Orientador estrangeiro: Prof. Dr. Gianfranco Butera
Tese submetida como requisito para obtenção de grau de Doutor ao Programa de Pós-Graduação em Ciências da Saúde, área de Concentração: Cardiologia ou Ciências Cardiovasculares, da Fundação Universitária de Cardiologia/Instituto de Cardiologia do Rio Grande do Sul.
Porto Alegre 2012
Bibliotecária Responsável: Marlene Tavares Sodré da Silva CRB 10/1850
M278f Manica, João Luiz Langer.
Dos Convencionais aos Recobertos: 15 anos de experiência de um centro terciário no tratamento percutâneo da coarctação de aorta com
stents; orientação [por] Rogério Sarmento Leite; Raul Ivo Rossi Filho; Mario Carminati; Gianfranco Butera. - Porto Alegre, 2012.
88f.; tab.
Tese (Doutorado) - Instituto de Cardiologia do Rio Grande do Sul / Fundação Universitária de Cardiologia - Programa de Pós- Graduação em Ciências da Saúde, 2012.
1.Defeitos cardíacos congênitos.2.Tratamento percutâneo.
3.Stent.4.Coarctação da aorta.I.Rogério Sarmento Leite.II.Raul Ivo Rossi Filho.III.Mario Carminati.IV.Gianfranco Butera.V.Título. CDU: 616.132-089.84
Aos meus pais, irmãos, cunhados e sogros; À minha esposa, em especial;
Ao Raul Ivo Rossi Filho,
Ao Paulo Machado, Rogério Sarmento Leite e Mônica Scott Borges;
Ao Gianfranco Butera, Mario Carminati, Luciane Piazza e à todos colegas da Itália;
Ao Ângelo de Souza, Maurício Reche, Fernanda Poester e Sérgio Kato da Unidade de Pesquisa;
Ao Paulo Zielinsky;
À todos colegas e residentes do Instituto de Cardiologia; Aos meus amigos,
pela maneira como participaram durante este período importante da minha vida.
SUMÁRIO
BASE TEÓRICA ... 1
1 INTRODUÇÃO ... 2
1.1 TRATAMENTO CIRÚRGICO E ANGIOPLASTIA COM BALÃO ... 3
1.2 IMPLANTE DE STENT NÃO-RECOBERTO... 4
1.3 STENTS RECOBERTOS NO TRATAMENTO DA COARCTAÇÃO DE AORTA ... 5
2 HIPÓTESE E JUSTIFICATIVA ... 11 3 OBJETIVOS ... 13 3.1 OBJETIVO GERAL ... 13 3.2 OBJETIVO ESPECÍFICO ... 13 4 REFERÊNCIAS ... 14 ARTIGO ORIGINAL ... 22 5.1 ABSTRACT ... 24 5.2 INTRODUCTION ... 26 5.3 METHODS ... 26 5.4 RESULTS ... 31 5.5 COMPLICATIONS ... 34 5.6 DISCUSSION ... 38 5.7 LIMITATIONS ... 45 5.8 CONCLUSIONS ... 46 5.9 REFERENCES ... 47 5.10 FIGURES ... 53 5.11 TABLES... 54 ARTIGO DE REVISÃO ... 57 6.1 SUMMARY ... 59 6.2 INTRODUCTION ... 60 6.3 EXPERT OPINION ... 66
6.4 FIVE YEAR VIEW ... 68
6.5 KEY ISSUES ... 69
6.6 BIBLIOGRAPHY ... 70
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1 INTRODUÇÃO
A coarctação de aorta representa aproximadamente 7% dos defeitos cardíacos congênitos com uma freqüência de cerca de 0,04% dos nascidos vivos. Compreende uma síndrome clínica de amplo espectro no que se refere à anatomia, fisiologia, apresentação clínica, tratamento e desfecho. Entretanto, envolve uma característica comum a todos que é o estreitamento da aorta resultando em obstrução do fluxo sangüíneo do ventrículo esquerdo para a circulação sistêmica.
Anatomicamente, pode se apresentar como uma lesão localizada na aorta descendente ou com um acometimento difuso de um longo segmento determinando hipoplasia do arco aórtico e, em casos extremos, associado à síndrome do ventrículo esquerdo hipoplásico. A manifestação clínica depende do grau de obstrução podendo se apresentar desde insuficiência cardiaca congestiva refratária do recém-nascido logo após o fechamento do canal arterial ou, ocasionalmente, ser diagnosticada em um adolescente ou adulto assintomático durante investigação de hipertensão arterial sistêmica.
1.1 TRATAMENTO CIRÚRGICO E ANGIOPLASTIA COM BALÃO DA COARCTAÇÃO DE AORTA
O tratamento cirúrgico da coarctação de aorta foi inicialmente descrito por Crafoord em 1945 e melhorou o prognóstico desses pacientes diminuindo a incidência de acidentes vasculares cerebrais, doença arterial coronariana e morte prematura. Entretanto, estudos de seguimento tardio demonstraram uma incidência de recoarctação entre 8 e 35% dependendo da técnica cirúrgica e do tempo de segiumento1-3.
Baseado em conhecimento prévio que a angioplastia com balão de lesões não ateroscleróticas pode causar ruptura da camada íntima e parte da camada média4, a dilatação com balão da coarctação de aorta foi então testada e descrita pela primeira vez
em 19815. Estudos iniciais demonstraram excelentes resultados em pacientes
previamente submetidos a reparo cirúrgico apesar de aumentada incidência de reintervenção em pacientes com longos segmentos estenóticos, hipoplasia ístmica ou obstruções leves 6-9.
Os altos índices de recoarctação em recém-nascidos, lactentes jovens e pacientes com hipoplasia ístmica 10-15 e a aumentada incidência de formação aneurismática seguindo a dilatação com balão de coarctação nativa 16, 17 tornaram controverso o seu uso nesse espectro de pacientes.
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1.2 IMPLANTE DE STENT NÃO-RECOBERTO
O implante percutâneo de stents em pacientes com doença arterial coronária e periférica, além do próprio uso em cardiopatias congênitas, vem crescendo nas últimas décadas18, 19. Ao prevenir o recuo elástico após dilatação com balão mantendo o aumento do diâmetro independente da injúria intimal, o implante do stent diminui a incidência de reestenose e se tornou uma alternativa terapêutica possível para pacientes com coarctação de aorta refratários à angioplastia com balão8, 20, 21.
Além disso, o implante percutâneo do stent permite adequada aposição da camada íntima à média evitando o enfraquecimento da parede vascular e prevenindo dissecção aórtica e formação aneurismática tardia 20-22. Primeiramente descrito em 1991
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, o implante de stent em coarctação de aorta tem se tornado amplamente utilizado e, após 17 anos de experiência e várias séries descritas, está demonstrado a efetividade do procedimento tanto para lesões nativas, bem como para defeitos residuais, assim como a manutenção do alívio imediato da obstrução no seguimento a médio prazo 20, 23-33.
Entretanto, apesar da diminuição da incidência de dissecção aórtica ou formação aneurismática quando comparados com a angioplastia com balão ou aortoplastia cirúrgica, esse risco parece não ter sido eliminado com o uso de stents. Estudos prévios reportam uma incidência de complicação relacionada à parede aórtica que varia entre 0 e 16%, sendo mais freqüente em pacientes com faixa etária elevada e aqueles com coarctação nativa extrema 23, 25, 27-31, 34-42.
1.3 STENTS RECOBERTOS NO TRATAMENTO DA COARCTAÇÃO DE AORTA
Esses achados levantaram a hipótese de que esses pacientes suscetíveis a complicações na parede aórtica provavelmente se beneficiariam do implante de stents recobertos com politetrafluoroetileno (e-PTFE) 23, 35. Essa técnica foi inicialmente descrita em 1999 para o tratamento de um paciente com coexistente aneurisma da parede aórtica 43. O sucesso do procedimento e o conhecimento prévio sobre o risco de complicação aórtica após o implante de stents não-recobertos em casos de coarctação severa aumentaram o espectro de pacientes beneficiados por esse dispositivo.
Em 2001, Cheatham descreveu pela primeira vez o uso do stent
Cheatham-Platinum® (CP) manualmente recoberto (NuMed, Hopkinton, NY, USA) para o
tratamento de um paciente com interrupção do arco aórtico e outro com coarctação de aorta severa a fim de prevenir possível formação aneurismática após o implante de stents não recobertos nesses pacientes 23. Entre 2001 e 2005, relatos e pequenas séries de casos confirmaram excelentes resultados imediatos de diferentes tipos de stents recobertos no tratamento da coarctação de aorta. Esses estudos contribuíram para aumentar o espectro de pacientes beneficiados por essa abordagem como pacientes com ducto arterioso patente, àqueles com condutos previamente implantados, àqueles com doença inflamatória e longos segmentos de estenose, àqueles com doença avançada e àqueles com ruptura aórtica após implante de stent não recoberto como terapêutica de resgate 44-50.
Entretanto, exceto por um caso descrito por DeGiovanni, o uso em crianças em fase de crescimento sempre foi desencorajado devido à incerteza sobre a possibilidade de redilatar esses stents sem danificar o e-PTFE 48. Em 2006, Tzifa e colaboradores publicaram os primeiros resultados de segmento tardio do implante de stents recobertos em pacientes jovens e adultos 51. Quatro pacientes neste estudo, portadores de lesões
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subatréticas, foram submetidos a abordagem seriada com redilatação planejada do stent recoberto previamente implantado, como já descrito por Ewert et al 45, 51. Tomografia computadorizada ou ressonância magnética realizadas três a seis meses após o procedimento documentaram a patência da luz do stent, além de excluírem a formação de aneurisma, bem como, sinais de recoarctação. Dois casos de fraturas de stent foram atribuídos ao tipo de stent que foi posteriormente reforçado por solda a ouro com aparente resolução do problema.
Em 2007, Butera e colaboradores extenderam o uso de stents recobertos para pacientes com dilatação de aorta ascendente, com parede aórtica irregular e aqueles previamente tratados com o uso de parches cirúrgicos devido ao risco aumentado de ruptura aórtica nesses pacientes 52. Além disso, pela primeira vez o uso de e-PTFE que cobre o stent CP® foi descrito como um material elástico possível de ser redilatado devido ao crescimento somático, e o uso em crianças foi então advogado. Essa possibilidade foi então confirmada em 2008 pelos mesmos autores em um estudo que descreve a redilatação dos stents recobertos em 7 pacientes em fase de crescimento 53. Os procedimentos foram realizados em uma média de 20 meses após o implante primário do stent. Não foi detectada alteração luminal dos stents entre o primeiro e o segundo procedimento, bem como, não houve complicaçãoes no seguimento em médio-prazo após a redilatação. Esses achados confirmaram a efetividade do implante de stents recobertos no tratamento de crianças em fase de crescimento.
Entretanto, outra preocupação que deve ser considerada durante o implante de stents recobertos em crianças é a necessidade do uso de bainhas de maior diâmetro, geralmente 3 french´s acima do necessário para a angioplastia com balão apenas, o que limita seu uso na população pediátrica. Por essa razão, Bruckheimer e colaboradores descreveram em 2009 uma abordagem seriada com a utilização inicial de balões
menores com o intuito de reduzir o tamanho do sistema de liberação requisitado, seguido por dilatações seriadas do stent já implantado com balões maiores 54. Apesar de esta abordagem permitir o implante de stents recobertos através de sistema de liberação 9 french, cuidados devem ser tomados para não aumentar o risco de mobilização ou migração devido à utilização de balões sub-estimados, sendo esta técnica mais efetiva nos casos mais graves com relação Balão/Coarctação maiores que 3.
Em 2010, o mesmo autor publicou a primeira experiência sobre os resultados imediatos de um novo stent recoberto de baixo perfil balão expansível para o tratamento percutâneo da coarctação de aorta, o Advanta V12® (Atrium, Hudson, NH, USA)55. Este stent é pré-montado em um balão não complacente de alta pressão com diâmetros que variam de 12 a 16mm. Essa característica permitiu que esse stent fosse implantado com sucesso em uma criança de 20 quilogramas sob uma bainha 8 french. Desde então, a indicação do tratamento percutâneo da coarctação de aorta com stents recobertos em crianças vem sendo ainda mais encorajada.
Apesar dos resultados iniciais e de médio-prazo promissores, a eficácia e a durabilidade do implante percutâneo de stents recobertos em coarctação de aorta ainda necessitavam de melhor avaliação. Para isso, Tanous et al realizaram avaliação hemodinâmica e angiográfica em 22 pacientes submetidos a implante percutâneo de stent recoberto independente da evolução clínica e ecocardiográfica em uma média de 12,1 meses após a primeira intervenção 56. Não foram diagnosticados casos de pseudoaneurisma ou deformidade da parede aórtica, bem como sinais de recuo elástico do stent ou hiperplasia neointimal relevante. Este achado vai de acordo com o que vem sendo preconizado em grandes centros mundiais que é a recomendação de stents recobertos a todos os adolescentes e adultos com coarctação de aorta independente da
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presença de aneurisma ou procedimentos prévios (comunicação pessoal, Pediatric and Adult Interventional Cardiology Symposium, Las Vegas, 2007).
Ainda assim, existem alguns aspectos que devem ser considerados no momento de decidir sobre o implante percutâneo de stents recobertos. A possibilidade de ocluir vasos que se originam da aorta é uma preocupação importante especialmente em se tratando de artérias que suprem a medula espinhal que pode resultar em paraplegia se ocluídas. Entretanto, essas artérias geralmente se originam abaixo do diafragma e raramente são ocluídas, exceto na presença de embolização do stent recoberto, o que ainda não foi relatado na literatura 57, 58. Apesar da proximidade com a área coarctada, a oclusão da artéria subclávia esquerda não representa uma grande preocupação. Como já demonstrado em pacientes pós-operatórios de “flap” de subclávia, o fenômeno de roubo que acontece em pacientes com o sistema vértebro-basilar intacto mantém retrogradamente o fluxo para o membro superior esquerdo. Parece prudente a realização de angiografia na artéria vertebral esquerda previamente ao procedimento para documentação deste fenômeno em pacientes de alto risco de oclusão da artéria subclávia esquerda 54, 59.
A migração do stent é raramente um evento tardio e como previamente mencionado, nunca foi relatado após o implante de stents recobertos. Isto pode estar
relacionado ao desenvolvimento do balão BIB® (NuMed balloon-in-balloon,Hopkinton,
NY, USA) que proporciona melhor controle da posição do stent 23, 34 e à experiência prévia com o uso de stents não recobertos que demonstrou alguns fatores de risco que devem ser evitados durante o implante de stents recobertos como a presença de cateter balão maior que a aorta proximal ao sítio da coarctação e o uso de balões sub-estimados, principalemente em casos de pseudocoarctação 24, 27, 28, 35, 40. O uso de adenosina e marcapasso temporário durante o a liberação do stent foram descritos em
séries de stents não recobertos para evitar a migração do stent, porém, apenas 1 estudo de stents recobertos mencionou o uso desta abordagem preventiva em casos de regurgitação aórtica ou lesões leves 60.
O risco de complicações da parede aórtica se tornou quase nulo após a introdução dos stents recobertos para o tratamento da coarctação de aorta. Apenas 3 casos deste tipo de complicação foram descritos na literatura após o uso de stents recobertos. Um caso de dissecção aórtica e outro de hematoma aórtico com extravasamento de contraste aconteceram após pós-dilatação da porção distal do stent (“Flaring”). Ambos foram subsequentemente tratados com o implante de outro stent recoberto como procedimento de resgate 54, 61. A necrose medial cística presente na área pós-estenótica pode favorecer o aparecimento de dissecção aórtica ou ruptura 16 demonstrando que a controversa pós-dilatação distal para acomodação da malha do stent com a parede aórtica pode acarretar em mais riscos do que benefícios. O outro caso de ruptura aórtica aconteceu em uma porção proximal do stent implantado em um paciente submetido à reparo cirúrgico prévio (“flap” de subclávia), reforçando o risco de complicações nesse grupo de pacientes 60.
A reestenose do stent recoberto não parece ser um evento comum e quase sempre acontece como parte de um procedimento seriado previamente planejado devido à severidade da lesão ou devido ao crescimento somático do paciente. Há apenas 1 caso descrito na literatura de proliferação neointimal extensa após o implante percutâneo de stent recoberto em uma criança de 12 anos, redilatada com sucesso após 17 meses, sem outras complicações durante o seguimento de longo prazo 62. Além disso, o implante de stent recoberto pode ser usado como resgate em paciente com severa hiperplasia neointimal após o implante de stent não recoberto, como já descrito na literatura 63.
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Em conclusão, os autores sugerem que o implante de stent recoberto no tratamento da coarctação de aorta possui um papel muito mais importante que o que pensávamos inicialmente. A crescente experiência tem ampliado as indicações não apenas para o manejo de complicações de procedimentos prévios, defeitos associados ou populações específicas. Nós acreditamos que a maioria dos casos de coarctação de aorta em adolescentes e adultos devem ser tratados com o implante percutâneo de stents recobertos.
Ainda aguardamos para uma melhoria na tecnologia com o advento de stents biodegradáveis e o desenvolvimento de sistemas de liberação capazes de serem usados nas artérias femorais de lactentes, apesar do uso em crianças acima de 20 quilogramas já ser uma realidade
Pacientes com lesões leves e aumentado risco de embolização do stent, aqueles com hipoplasia de arco aórtico e risco de oclusão dos vasos da base, bem como na não disponibilidade dos stents recobertos, stents não recobertos devem ser considerados para o tratamento da coarctação de aorta.
2 HIPÓTESE E JUSTIFICATIVA
A hipótese é de que o uso de stents não recobertos está associado ao aparecimento de complicações da parede aórtica, ainda que em menor número se comparado com outras opções terapêuticas como a cirurgia e a angioplastia com balão. Ainda, a utilização de stents recobertos, além de ser uma excelente ferramenta de resgate nos casos complicados por ruptura aórtica ou pseudoaneurisma, deve prevenir o aparecimento deste tipo de complicação quando utilizados de forma primária.
Stents recobertos são rotineiramente utilizados em vários centros mundiais em pacientes com coarctação de aorta. Todavia, em nosso meio, são mais onerosos e não são disponibilizados por muitas fontes pagadoras, entre as quais o Sistema Único de Saúde (SUS). Considerando o potencial benefício dos stents recobertos, acredita-se que o seu uso sistemático reduza complicações e necessidade de os pacientes submeterem-se a novos procedimentos corretivos. Esta proposta tem como principal contribuição científica original a comparação da utilização destas duas possibilidades terapêuticas. Os resultados deverão orientar a escolha do dispositivo mais adequado para cada caso e os diferentes tipos de lesões e possíveis complicações relacionadas a cada abordagem.
A impossibilidade de utilização irrestrita de stents recobertos para o tratamento de coarctação de aorta em nosso meio impede a realização de tal estudo sem que haja a interação com um centro de referência em nível mundial. Além disso, a possibilidade de estabelecer uma relação de cooperação com um dos maiores centros de ensino e pesquisa em cardiologia pediátrica da Europa e de promover linhas de pesquisa para colaboração permanente entre os dois centros pode significar um avanço extraordinário para o desenvolvimento da cardiologia pediátrica no Brasil.
Como conseqüência prática deste estudo, as informações obtidas resultarão em uma maior efetividade e segurança do tratamento percutâneo da coarctação de aorta a
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partir da escolha adequada do dispositivo. Além disso, acredita-se que a menor taxa de complicações, especialmente de pseudoaneurisma, obtida com a utilização de stents recobertos resulte em um menor número de crianças submetidas a sucessivas reintervenções.
3 OBJETIVOS
3.1 OBJETIVO GERAL
Descrever os resultados imediatos e o seguimento em médio prazo da utilização de stents não recobertos (Grupo 1) para o tratamento de coarctação de aorta na comparação com o uso de stents recobertos (Grupo 2) com relação à taxas de sucesso, necessidade de reintervenção e incidência de complicações.
3.2 OBJETIVO ESPECÍFICO
Definir fatores de risco para o aparecimento de complicações ou necessidade de reintervenção após o tratamento percutâneo da coarctação de aorta com stents.
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39. Qureshi AM, McElhinney DB, Lock JE, Landzberg MJ, Lang P, Marshall AC. Acute and intermediate outcomes, and evaluation of injury to the aortic wall, as based on 15 years experience of implanting stents to treat aortic coarctation. Cardiol Young 2007; 17(3):307-18.
40. Suarez de Lezo J, Pan M, Romero M, et al. Immediate and follow-up findings after stent treatment for severe coarctation of aorta. Am J Cardiol 1999; 83(3):400-6.
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45. Ewert P, Abdul-Khaliq H, Peters B, Nagdyman N, Schubert S, Lange PE. Transcatheter therapy of long extreme subatretic aortic coarctations with covered stents. Catheter Cardiovasc Interv 2004; 63(2):236-9.
46. Forbes T, Matisoff D, Dysart J, Aggarwal S. Treatment of coexistent coarctation and aneurysm of the aorta with covered stent in a pediatric patient. Pediatr Cardiol 2003; 24(3):289-91.
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49. Sadiq M, Malick NH, Qureshi SA. Simultaneous treatment of native coarctation of the aorta combined with patent ductus arteriosus using a covered stent. Catheter Cardiovasc Interv 2003; 59(3):387-90.
50. Tan JL, Mullen M. Emergency stent graft deployment for acute aortic rupture following primary stenting for aortic coarctation. Catheter Cardiovasc Interv 2005; 65(2):306-9.
51. Tzifa A, Ewert P, Brzezinska-Rajszys G, et al. Covered Cheatham-platinum stents for aortic coarctation: early and intermediate-term results. J Am Coll Cardiol 2006; 47(7):1457-63.
52. Butera G, Piazza L, Chessa M, et al. Covered stents in patients with complex aortic coarctations. Am Heart J 2007; 154(4):795-800.
53. Butera G, Gaio G, Carminati M. Redilation of e-PTFE covered CP stents. Catheter Cardiovasc Interv 2008; 72(2):273-7.
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54. Bruckheimer E, Dagan T, Amir G, Birk E. Covered Cheatham-Platinum stents for serial dilation of severe native aortic coarctation. Catheter Cardiovasc Interv 2009; 74(1):117-23.
55. Bruckheimer E, Birk E, Santiago R, Dagan T, Esteves C, Pedra CA. Coarctation of the aorta treated with the Advanta V12 large diameter stent: acute results. Catheter Cardiovasc Interv 2010; 75(3):402-6.
56. Tanous D, Collins N, Dehghani P, Benson LN, Horlick EM. 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):287-95. 57. Connolly JE. Hume Memorial lecture. Prevention of spinal cord complications in
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58. Wada T, Yao H, Miyamoto T, Mukai S, Yamamura M. Prevention and detection of spinal cord injury during thoracic and thoracoabdominal aortic repairs. Ann Thorac Surg 2001; 72(1):80-4; discussion 5.
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60. Kenny D, Margey R, Turner MS, Tometzki AJ, Walsh KP, Martin RP. Self-expanding and balloon expandable covered stents in the treatment of aortic coarctation with or without aneurysm formation. Catheter Cardiovasc Interv 2008; 72(1):65-71.
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ARTIGO ORIGINAL
FROM BARE TO COVERED: 15-YEARS SINGLE CENTER EXPERIENCE IN TRANS-CATHETER STENT IMPLANTATION FOR AORTIC COARCTATION
Artigo para publicação March 2012
FROM BARE TO COVERED: 15-YEARS SINGLE CENTER EXPERIENCE IN TRANS-CATHETER STENT IMPLANTATION FOR AORTIC COARCTATION
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ABSTRACT
Objective: To report the 15-year experience of bare and covered stent implantation for aortic coarctation in a single tertiary referral center. Background: Since being introduced, bare stent placement has become the first line therapy for native aortic coarctation or recoarctation. The use of covered stents was first reported to treat aortic wall complications but more recently they have been used for an increasing number of patients with aortic coarctation. Methods: From 1997 to 2011, 143 patients with native or post-operative aortic coarctation were treated with percutaneous stent implantation at our institution. Seventy-one patients with a median age of 17 years (range from 4 to 70 years) and a median weight of 55.25 Kg (range from 13 to 94 Kg) underwent bare stent implantation (Group 1) and 72 patients with a median age of 17.5 years (range from 6 to 68 years) and a median weight of 61.56 Kg (range from 22 to 110 Kg) underwent covered stent implantation (Group 2). Success rate in the whole group was 95% with no differences between the two subgroups. More complex and tighter coarctations were treated using covered stents. Incidence of related-procedure adverse events was higher in group 1 than in group 2 (21.12% versus 8.3% p = 0.035). Aortic wall complications occurred in 7% of patients in group 1 (one death) while no complications occurred in group 2 (p = 0.028). Stent migration occurred in group 1 and it was higher in subjects with mild lesions (balloon/Coarctation diameter < 1.5). Length of follow-up was 58.11±37.81 years. Subjects in group 1 had a longer follow-up (81.70±33,58 versus 36±24.81 years, p < 0.001). Independent predictors associated with reintervention after percutaneous stent placement in patients with aortic coarctation included the presence of complex lesions (HR: 2.70; CI: 1.15 to 6.32; p = 0.023), balloon diameter used < 14mm (HR: 3.76; CI: 1.48 to 9.55; p = 0.005) and residual gradient > 10mmHg (HR: 4.30; CI: 1.96 to 9.47; p < 0.001). Conclusions: Both bare and covered stent implantation for aortic coarctation is a safe and efficacious treatment.
[s1] Comentário: Time interval taken to
Recently, the spectrum of patients treated by using covered stent implantation has increased with lower rates of acute and late complications.
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INTRODUCTION
Aortic coarctation accounts for about 7% of known congenital heart defects with a frequency of approximately 0.04% of live births. Since it was first reported in 1991 1, bare metal stent implantation for aortic coarctation has become a widely performed procedure, proving safe and effective for both residual and native lesions. It provides excellent immediate relief of the obstruction and maintains beneficial effects at medium term follow-up with a low incidence of complications 2-9. Although covered stents were first described to treat vessel complications as a bail out procedure 10-12, recent reports have shown that these stents can be used as a safe and reliable primary procedure for a specific spectrum of patients with aortic coarctation 13-15. The objective of this study was to report the 15-year single center experience of bare and covered stent implantation for aortic coarctation and to compare the follow-up of both procedures regarding success, need for reintervention, and complication rate.
METHODS
From 1997 to 2011, 143 patients with native or post-operative aortic coarctation were submitted to percutaneous stent implantation at our institution. Patients were referred for aortic coarctation relief when blood pressure gradient between upper and lower limbs was greater than 20 mmHg at rest or less than 20 mmHg but associated to significant systemic arterial hypertension at rest and/or at exercise with associated left ventricular dysfunction or hypertrophy.
DEFINITIONS
Complex aortic coarctation was defined as those cases in which the subject had aortic inflammatory disease, previous conduit or patch implantation, atresic or subatresic
segments, a proximal aorta/coarctation segment ratio > 3 (Ao/CoAo ratio), or in those patients who had associated dilatation of the ascending aorta, aneurysm formation or an irregular aortic wall 11,13,15-19.
Immediate intervention success was defined as stent implantation in the appropriate position occurring without complication and with an invasive peak-to-peak systolic gradient across the aortic isthmus < 20mmHg.
Complications were defined as aortic wall complications (aortic hematoma, dissection, aneurysm or rupture), technical complications (stent mobilization or embolization) and peripheral vascular complications (cerebral ischemic symptoms and access related complications) as already described in the literature 16.
Patients were divided into two groups with respect to the type of stent implanted. Group 1 included patients receiving bare stents and group 2 included those in whom covered stent implantation was performed.
PROCEDURE
All patients underwent general anesthesia with orotracheal intubation. Informed consent was obtained from all patients or their parents prior to the procedure. Intravenous heparin (100 IU/kg, maximum of 5000 IU) was given immediately after femoral artery cannulation, achieved by using an 8F introducer. The stenotic segment was crossed by a 6F multipurpose catheter and a floppy guide wire (0.035-in. Terumo guide wire). The catheter was then exchanged with a standard 0.035-in., 260-cm Exchange guide wire for a pigtail catheter. The pressure gradient was measured between the 8F femoral sheath and the pigtail catheter located in the ascending aorta. Anteroposterior, 40° left anterior oblique and lateral angiograms were obtained with the holes of the pigtail catheter close to the stenotic area. The following measurements were obtained from the angiography: (1) diameter and length of the
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stenotic area, (2) diameter of the descending aorta at the level of the diaphragm, (3) diameter of the aorta at the level of the subclavian artery, and (4) diameter of the transverse arch. The diameter of the balloon for dilatation was chosen to be equal to that of the distal arch at the level of the origin of the subclavian artery. If hypoplasia of the distal arch was present, the diameter of the transverse arch was used to choose the balloon. When a near atretic aortic coarctation was found, we performed predilation of the aortic segment using coronary balloons. The balloon catheter was chosen to be longer than the stent length. The length of the stent was determined by the distance from just beyond the left subclavian artery or the left common carotid if the left subclavian artery had been sacrificed in previous surgery, to about 10 to 15 mm beyond the site of the coarctation. BIB balloons (NuMED Inc, Cornwall, Ontario,Canada) or Crystal balloons (BALT, Montmorency, France) were used. Mullins transseptal long sheaths (Cook Europe, Bjaeverskov, Denmark) were chosen to be 1 Fr to 2 Fr larger than the sheath needed for balloon only when bare stents were implanted and 3 Fr to 4 Fr larger for covered stents. Long sheaths ranging from 8F to 14F were used. The Mullins sheath was exchanged over a 0.035-in. stiff guide wire positioned in the ascending aorta or in the right subclavian artery. The balloon with the stent was manually inflated in the correct position, up to the pressure recommended by the manufacturer, which was usually up to 4 to 6 atm. Angiography was performed during and after the placement of the stent through the side arm of the sheath or by using a pigtail to assess the result and rule out dissection or rupture of the aorta. Pressures were recorded after the procedure. Hemostasis was achieved by manual compression, hemostatic devices as Perclose™ (Abbott, IL, USA) or Angioseal™ (St Jude Medical, St. Paul, MN) or by surgical repair. All patients received cephalosporin for 24 hours and aspirin at a dose of 3 to 5 mg/kg once a day for 6 months after the implantation..
POSTOPERATIVE CARE
To monitor the arterotomy site, gastrointestinal symptoms, and rebound hypertension, the patients were kept in hospital for 2 to 3 days after the procedure prior to discharge.
FOLLOW-UP PROTOCOL
Outpatient follow-up consisted of clinical assessment including blood pressure and need for antihypertensive medication, 12-lead ECG, chest x-ray and transthoracic echocardiogram at 1, 3, 6, 12 months and then yearly. Spiral computed tomographic scan (CT) and ergometry were recommended to be performed at three months and then 12 months after procedure.
The need for additional investigation was determined based on clinical status, echocardiographic and CT findings. Patients were not routinely referred for recatheterization during follow-up.
STATISTICAL ANALYSIS
The following dependent outcome variables were analysed: age, sex, weight, age group (<15 yrs , >15 yrs), type of coarctation (native or recoarctation), type of lesion (simple, complex), aortic hypoplasia (yes/ no), aortic arch measurement, pre-operative peak-to-peak gradient, introducer French size, balloon diameter, stent type (bare, covered), hemostasis method (manual, device assisted or surgical), balloon:coarctation ratio, post-operative gradient, procedural complication (yes/ no), type of complication, mortality (yes/ no), follow-up (months), reinterventions (yes/no) and its causes (neointimal hyperplasia, localized stenosis, somatic growth and fracture).
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Descriptive statistics such as mean, median, SD, interquartile intervals and frequency were calculated for each demographic and clinical or anatomical characteristic wherer appropriate.
Univariate analysis was performed using the χ2 test, Fisher's exact test, unpaired Student's t-test, Wilcoxon rank sum test, and paired t-test as appropriate.Multivariable analysis was performed using multiple logistic regression analysis to study risk factors associated with complications. Independent variables with a P-value <0.2 in the univariate analysis were included in the multivariable model. Odds ratios and their 95% confidence intervals were calculated for independent variables included in the multivariable model.
Multivariable analysis using Cox proportional hazard regression analysis was performed to study the role of group, weight, age, the presence of aortic arch hypoplasia, complex lesion, balloon diameter and residual gradient > 10mmHg on the occurrence of reintervention in the early period and during the follow-up. Evaluation of proportional hazards assumption was performed using the goodness-of-fit testing approach. All tests were two-sided. A probability value of P < 0.05 was considered statistically significant.
RESULTS
GENERAL CHARACTERISTICS
Among the 143 patients the median age was 17 years (range from 4 to 70 years), mean weight was 59±19.88 kg, there was a male predominance (63.63%) and 71.32% of patients had native aortic coarctation.
Group 1 included 71 patients with a median age of 17 (range from 4 to 70 years-old) and a mean weight of 55.25 ± 19.22 kg (range from 13 to 94 kg) of which forty-six patients (64.8%) were diagnosed with native coarctation at the time of the procedure. Group 2 comprised 72 patients with a median age of 17.5 years (range from 6 to 68 years-old) and a mean weight of 61.56 ± 20.17 g (range from 22 to 110 kg), of which fifty-six (77.8%) had a diagnosis of native coarctation at the time of the procedure. Other data are reported in table 1. Between 1997 and 2004 we performed 57 of the 71bare stent procedures. 68 of the 72 covered stent implantations were performed between 2005 and 2010.
The following bare stents were used: Palmaz® stent (Cordis Corporation, Miami, USA) in 57.7% of cases, Palmaz-Genesis® (Cordis Corporation, Miami, USA) in 21.1%, Cheatham-Platinum (CP) stents (NuMed Inc., Hopkinton, NY, USA) in 18.3% and Andrastent (Andramed GmbH, Germany) in 2.9% of cases.
The covered stents used were predominantly 8-zig CP covered stents (NuMed Inc., Hopkinton, NY, USA) in 86.1% of cases and the Advanta V12 LD stent (Atrium Medical, NH) in 12.5% of cases. In the first case of our covered stent experience, we used a Palmaz stent covered by hand sewing on ePTFE, no longer used after the introduction of the CP covered stents (NuMed Inc., Hopkinton, NY, USA). The covered CP stent is a CP bare stent covered with an expandable sleeve of ePTFE, available in lengths from 16 to 45mm that can be dilated up to a maximal diameter of 24mm. The Advanta V12 LD stents (Atrium Medical, NH) are available in three lengths (29, 41 and 61mm) and are premounted on balloons of 12,
[s2] Comentário: 63.6%? One decimal
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14 and 16mm and can be dilated up to a maximal diameter of 22mm.
No differences were found between the groups on comparison of sex, age, or type of aortic coarctation (Table 1). Patients who underwent covered stent implantation were more commonly affected by complex aortic coarctations (75%), with more severe cases on comparison to patients who received a bare stent (Table 1).
The procedure was performed in the catheterization laboratory using a femoral retrograde approach as the primary access in all patients. Five patients from group 2 needed concomitant radial or brachial access due to aortic atresia or subatresia and two of them required a radio-frequency catheter to perforate the aorta and establish a connection between ascending and descending aorta. Experience concerning these subjects has been recently published 20. Only one subject in group 1 with subatretic aortic coarctation needed an additional radial approach.
EARLY PROCEDURAL DATA AND RESULTS
One hundred fifty-three stents were implanted in 143 patients at the first procedure with an immediate success rate of 95%. No differences were found when comparing success rate in groups 1 and 2 (95.4% versus 95.8% respectively, p = ns). At the end of the procedure only three patients in group 1 (4.2%) had a residual gradient of 20mmHg or more. All of them had aortic arch hypoplasia. Except for one patient with mild lesion in whom it was not possible to deliver the stent in the right position, all others presented severe aortic coarctation (mean Ao/CoAo ratio 4 and 4.6). Similarly, among the 3 patients in group 2 with post-stent gradient ≥ 20mmHg, two had severe aortic coarctation (mean Ao/CoAo ratio 11.7 and 4.5) and two had associated aortic arch hypoplasia. Both groups showed significant reduction in the measured peak-to-peak gradient before and after the procedure (Table 1). In group 1, mean peak-to-peak gradient diminished from 39.28 ± 14.53 mmHg before stent implantation
to 4.69 ± 6.03 mmHg after the procedure (p<0.001). Similarly in group 2, the mean gradient before the procedure was 39.42 ± 13.58 mmHg and decreased to 5.26 ± 6.64 mmHg after stent implantation (p<0.001). No difference was found when both pre and post-procedure peak-to-peak gradients were compared between the two groups (Table 1).
Coarctation diameter improved significantly in both groups. In group 1, the mean smallest coarctation diameter increased from 7.29 ± 2.77 mm to 14.86 ± 3.82 mm (p<0.001) with a mean increase in diameter of 7.78 ± 2.74 mm. In group 2, the mean smallest coarctation diameter increased from 5.37 ± 3.08 mm to 13.67 ± 3.58mm (p<0.001) with a mean increase in diameter of 8.18 ± 3.24 mm (Table 1).
No statistically significant difference was found between the two groups regarding post-procedure diameter. However, mean minimal pre-procedural diameter was significantly smaller in group (p < 0.001) 2. Furthermore, the mean balloon/aortic coarctation ratio was higher confirming a trend of more severe lesions in group 2 (Table 1). Moreover, only 13 patients in group 1 (21.7%) had balloon/coarctation ratio > 3 whereas in group 2 it occurred in 31 (43.1%) (p = 0.016).
A significant difference was found between groups in the method of haemostasis at the end of the procedure.. In group 1, 77.5% of patients had manual compression hemostasis compared to only 9.7% of patients in group 2 (p < 0.001). In addition, among patients undergoing covered stent implantation, 63.9% had surgical hemostasis whilst this occurred in only 7 patients (9.9%) in group 1 (p < 0.001). In the remaining cases Perclose™ (Abbott, IL, USA) and Angioseal™ (St Jude Medical, St. Paul, MN) devices were used to perform hemostasis. There was no association between the method of hemostasis and the incidence of vascular complications (p > 0.05).
[s3] Comentário: p value?
[s4] Comentário: Insert a comment ast
to why this was so different? Bigger stents in group 2 requiring bigger vascular sheaths so need for definitive repair?
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COMPLICATIONS
OVERALL COMPLICATIONS
The overall incidence of related-procedure complications was 14.68%. This incidence was not influenced by sex (p = 0.811), age (p = 0.466), type (p = 0.795), presence of non complex lesion (p = 0.147), aortic arch hypoplasia (p = 0.546), type of hemostasis (p = 0.546) and balloon diameter used to deliver the stent (p = 0.629). However, it was more frequently encountered in patients from group 1 (21.12% versus 8.3% respectively, p = 0.035) and those with balloon/coarctation ratio < 1.5 (p = 0.024). Variables with a p value < 0.2 in the univariate analysis were further entered into a multivariable logistic regression model. Independent predictors associated with complications after aortic stent implantation were patients who had bare stents (OR: 3.29; CI: 1.15 to 9.40; p = 0.026) and balloon/coarctation ratio < 1.5 (OR: 3.84; CI: 1.18 to 12.50; p = 0.025). The Hosmer and Lemeshow test showed that this model provided good fit with the data (p = 0.866).
AORTIC WALL COMPLICATIONS
Aortic wall complications were seen in 5 patients in group 1 (7%) and in no patients in group 2 (p = 0.028). Of these patients, 4 underwent Palmaz® stent (Cordis Corporation, Miami, USA) implantation and one received a Palmaz-Genesis® stent (Cordis Corporation, Miami, USA). One patient developed mild acute aortic hematoma, spontaneously resolving after 3 months, and aortic aneurysm formation was diagnosed in 3 patients (4.5%) during follow-up. All underwent successful covered stent implantation. Finally, one patient previously submitted to end-end surgical anastomosis and percutaneous balloon dilatation complicated by aneurysm formation, underwent bare stent implantation and aneurysm coil occlusion, but died 2 hours after the procedure secondary to aortic rupture.
TECHNICAL COMPLICATIONS
Technical complications occurred in group 1 to 7 patients (9.85%). Stent embolization to the thoracic or abdominal aorta occurred in 5 patients (7%); in one patient stent mobilization occurred during implantation requiring the implantation of another stent and in another the balloon migrated during stent delivery and a second balloon was then successfully expanded within the stent. In group 2 there were no cases of stent embolization. In two cases the stents moved proximally during implantation. They did not embolize but they were stabilized by implanting a longer covered stent. The incidence of stent embolization was significantly higher in patients submitted to bare stent implantation (p = 0.028). If we consider the overall incidence of technical complications (6.3%), they were much more frequently encountered in patients with milder lesions (6/17: 35%; p = 0.031) and in those with a balloon/coarctation diameter ratio < 1.5 (7/58:12%; p < 0.001) and were not influenced by aortic hypoplasia, balloon diameter and group.
PERIPHERAL COMPLICATIONS
The incidence of peripheral vascular complications was similar between both groups (4.2% versus 4.1% p = 1.00). Among the three patients in group 1, two of them developed arterio-venous fistula requiring surgical correction. In group 2, one patient developed an asymptomatic femoral artery stenosis following surgical hemostasis, one developed a small arterio-venous fistula which spontaneously resolved and one who underwent bilateral radial access to assist with an antegrade radio-frequency perforation developed left hand ischemia treated with alphaprostadil and heparin with complete resolution.
[s5] Comentário: Slightly unclear- did
stent embolization occur after implantation so another stent was required at the same site? In the second patient did the balloon move but stent stayed stable but not move so another balloon could get to correct position and deploy the stent?
[s6] Comentário: May need to
comment about need for pacing to prevent embolization? Whether they had higher systemic pressures at time of deployment may be worth commenting?
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FOLLOW-UP
Length of follow-up was 58.11 ± 37.81 months. Subjects in group 1 had a longer follow-up (80.50 ± 34,78 versus 34.54 ± 25.11 months, p < 0.001). Eight patients (5.59%) were lost at follow-up in the whole group.
In the group 1 three patients were lost to follow-up (4.28%). Among the sixty-seven patients that were followed-up for a median of 81.7 months (range from 7 to 149 months), 16 patients (23.88%) needed reintervention due to restenosis at a mean of 49.4 months (range from 8 to 111 months) after the first procedure and 3 (4.47 %) needed reintervention due to aneurysm formation at a mean of 45 months (range from 18 to 78 months) after the procedure.
In group 2, 5 patients (6.94%) were lost to follow-up. Among the sixty-seven patients that were followed-up for a median of 36 months (range from 1 to 100 months), 15 patients (22.38%) needed reintervention due to restenosis at a mean of 18.4 months (range from 4 to 39 months) after the first procedure and in one patient another stent was implanted to stabilize a mobile fractured cell.
Causes of restenosis were described as neointimal hyperplasia, localized stenosis, somatic growth (disproportion between stent diameter and proximal aorta without significant stent recoil) or fracture.
ANALYSIS OF RISK FACTORS FOR THE NEED OF REINTERVENTION Univariate analysis showed that the incidence of reintervention among the 143 patients was not influenced by sex (p = 0.128), weight (p = 0.187), group (p = 0.843) and type of coarctation (p = 0.413). However, age less than 15 years old (OR: 2.57; CI: 1.16 to 5.69; p = 0.025), the presence of aortic arch hypoplasia (OR: 4.85; CI: 1.91 to 12.27; p = 0.001), complex lesions (OR: 2.66; CI: 1.10 to 6.44; p = 0.041), use of a balloon <14mm in
diameterto deliver the stent (OR: 5.87; CI: 2.38 to 14.46; p < 0.001) and residual gradient more than 10mmHg (OR: 4.00; CI: 1.72 to 9.31; p = 0.002) were associated with reintervention during the follow-up period when univariate analysis or qui-square testing were performed (Table 2).
Multivariable analysis using Cox proportional hazard regression analysis showed that the presence of a complex lesion (HR: 2.70; CI: 1.15 to 6.32; p = 0.023), balloon diameter <14mm used to deliver the stent (HR: 3.76; CI: 1.48 to 9.55; p = 0.005) and residual gradient > 10mmHg (HR: 4.30; CI: 1.96 to 9.47; p = 0.001) were significantly associated with the need of reintervention during the follow-up period.
Neointimal hyperplasia (Figure 1) was observed in 12 patients (8.39%) during follow-up catheterization. The incidence was similar among both grofollow-ups: 7 (10.6%) in the bare stent group and 5 (7.5%) in patients with covered stents (p = 0.561). There were no cases of neointimal hyperplasia in adults submitted to covered stent implantation, while 3 cases were seen in the bare stent group. Neointimal hyperplasia was significantly associated with aortic arch hypoplasia and balloon diameter < 14mm (p = 0.012 and 0.003, respectively). Although not statistically significant, there was a trend to the presence of neointimal hyperplasia in patients with age < 15 years or lower weight (p = 0.061 and 0.056, respectively) and was not influenced by sex, type or complexity of the coarctation and group (Table 3).
The appearance of localized stenosis was more frequently encountered in patients with complex lesions (p = 0.027), aortic arch hypoplasia (p = 0.006), balloon < 14mm (p = 0.015), balloon/coarctation diameter ratio > 3 (p = 0.018) and residual gradient > 10mmHg (p < 0.001) (Table 3).
Somatic growth as cause of reintervention was associated to age < 15 years (p = 0.001) and the use of balloon less than 14mm of diameter (p = 0.005) nevertheless it was not
[s7] Comentário: % of all patients who
had stents OR % of those who had a repeat catheterization? Did al have repeat caths?
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associated to group, sex, age, weight, type and complexity of coarctation, balloon diameter and residual gradient > 10mmHg (Table 3).
Finally, 4 patients presented with stent fracture during follow-up in group 1 and 3 of those required reintervention due to restenosis. One patient in group 2 developed stent fracture and required further stent implantation to stabilize the stent position, despite absence of a residual gradient. There were no risk factors associated with stent fracture but it was only observed with Cheatham-Platinum (CP) stents (NuMed Inc., Hopkinton, NY, USA).
Spiral computed tomographic scan (CT) or MRI was performed in 76.1% of patients in group 1, the last CT being a mean of 56.4 months after the first procedure. In group 2, 71.6% of patients had a CT scan, the last CT being performed a mean of 21.7 months after the first procedure. CT scan evaluation assisted in finding out which cases were complicated by aneurysm formation (Figure 2).
DISCUSSION
Since the first report of transcatheter balloon angioplasty for aortic coarctation in 1982 21, the endovascular treatment of cardiovascular diseases has developed significantly. Despite the promising results of balloon angioplasty for residual postoperative aortic coarctation, its use for the relief of native coarctation instead of surgery was controversial until the end of 80’s. Initial studies demonstrated similar results of immediate gradient reduction and mortality with a significant incidence of recoarctation in newborns, young infants and patients with isthmus hypoplasia 22-25 in addition to increased incidence of aneurysm formation 26,27. Stent implantation helps to support the vessel after balloon dilation and maintains the effectiveness of dilatation regardless of intimal injury 5,16. It theoretically decreases the incidence of restenosis and has become a viable alternative therapy for patients with aortic coarctation 28. Moreover, the placement of endovascular stents reapplies the
intima to the media layer avoiding significant wall weakening and preventing aortic dissection and late aneurysm formation 28,29. Firstly reported in 1991 1, bare stenting for aortic coarctation has become widely performed and several case series have been already published since these first reports 2-9. However, the occurrence of vessel damage was not eliminated. Various studies have reported the association between aneurysm formation and overaggressive dilation of severe aortic coarctation, balloon pre-dilation, treatment of older patients and with the sharp edges of the stents used in the first initial series 9,17,30-35. The need for larger sheaths compared to balloon angioplasty is another concern and probably limits its use in the pediatric population. However, the use of smaller balloons, the possibility of redilating these stents in the long term by performing a staged approach or even to accommodate somatic growth, and the development of low-profile balloon expandable stents are some alternatives described in successful series of aortic coarctation stent implantation
16,29,35-39.
The use of covered stents with polytetrafluoroethylene (e-PTFE) was firstly reported to treat aortic wall complications with promising results 10-12. Afterwards, this technique started to be performed not only to deal with complications from previous procedures but also to prevent them. Previous studies reported the successful experience of covered stent implantation for complex aortic coarctations and patients with advanced aged 13-15. The possibility of redilating covered stents has also been described 40. More recently, with the advent of new low-profile stents 41, the spectrum of patients who may benefit from this approach has been increasing, but the indications are still not well defined.
In our institution, we have been implanting bare metal stents for the percutaneous treatment of aortic coarctation since 1997 and covered stents first became available for use in 2002. A total of 143 subjects have been treated to date. To our knowledge, this is the first report comparing both percutaneous approaches in aortic coarctation. In this study we
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demonstrate the feasibility, safety and efficacy of bare and covered stent implantation for native or residual aortic coarctation in children and adults.
In particular, more tight and complex coarctations were treated by covered stents than by bare stents alone. Furthermore, we found a lower incidence of acute aortic wall related complications. The overall incidence of complications (15%) was exactly the same as encountered by Forbes in the largest multi-institutional series already published in literature
16.
COMPLICATIONS
When comparing the incidence of aortic wall complications between the 2 groups, there was an advantage for patients undergoing covered stent implantation with no report of dissection, pseudoaneurysm or aortic wall rupture in those subjects. The 7% incidence of aortic wall complication in patients undergoing to bare stent implantation in our series was similar to most series to date ranging from 0 to 11% 2,4,5,9,16,30,39,42-45. No particular variables appeared associated with this event due to the small number of complications but 4 cases followed Palmaz stent implantation (Cordis Endovascular, Warren, NJ, USA); 2 cases after overaggressive dilatation of native aortic coarctation and 2 cases after balloon predilation. All of these features have been already described as risk factors for aortic complication after stent implantation 5,8,9,16,30,32-35,45. Interestingly, there were no cases of aortic wall complication in patients older than 30 years old. The absence of such complications in group 2 may indicate an advantage of covered stent use. Although Pedra et al reported 2 cases of aneurysm formation after covered stent implantation 15 and, together with other authors, recommended staged covered stent dilatation in patients with severe aortic coarctation or markers of aortic wall weakness 46, in the last few years, our policy has been to dilate to the full planned diameter in one stage.
The low incidence of technical complications has substantiated the safety of stents for aortic coarctation. The occurrence of distal stent migration after bare stent implantation (7%) was similar to that described in the literature 2,6,7,16,44,45. Covered stent embolization has never been reported in literature and must be avoided due to the risk of side branch occlusion, especially with regards to the spinal arteries. In this study we described two cases with covered stent mild malposition during delivery. In one case a 28mm CP covered stent® (NuMed, Hopkinton, NY, USA) deployed in a mild lesion (balloon/coarctation ratio 1.3) proximally displaced during post-dilatation and another longer stent was implanted. In the other patient, with a diagnosis of pseudocoarctation and balloon/coarctation ratio of 1.5, a 34mm CP covered stent® (NuMed, Hopkinton, NY, USA) had slight distal mobilization during post-dilatation and again another longer stent was implanted.
In our study the presence of balloon/coarctation diameter ratio < 1.5 and the absence of complex lesions were highly associated with bare stent malposition or migration. Bruckheimer warned that the use of a lower balloon/coarctation ratio risks stent embolization due to inadequate stent anchorage to the aortic wall 41,46. Forbes described this kind of complication is risked in mild lesions, underestimated balloon size and with balloon diameter larger than the proximal aorta 16. In this study, the majority of cases with technical complications happened during post-dilatation with balloons slightly bigger than proximal aorta, apart from a case in a patient with pseudocoarctation. Interestingly, in this study, mobilization was resolved in 2/3 of these cases by implantation of stents longer than those in the first deployment, mounted on the same balloons as used for post-dilatation. This observation underlines that stent length is more important than balloon diameter. The use of longer stents to prevent stent embolization has been already described in the literature 9. Although this fact is not statistically significant in the numbers in our study, it highlights the risk of stent embolization when short stents are used, mainly in patients with mild lesions and
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balloon/coarctation diameter ratio < 1.5. Balloon rupture has been already published as another risk factor for stent migration 6 but was not seen in our study. In addition, no patient was submitted to rapid right ventricular pacing as a maneuver to reduce systolic blood pressure and avoid stent embolization. The decreasing incidence of stent migration in the last covered stent series can probably be related to the previous experience with bare stents and the use of the balloon-in-balloon catheter (BIB, NuMED Inc.) that provides better control during stent deployment 5-7,17,32.
Although patients subjected to covered stents required larger long sheaths than in those patients subjected to bare stents, there were no differences in the incidence of vascular access-related complications. In the group 1, 2 patients developed arterio-venous fistula requiring surgical repair, both who had to manual compression hemostasis. The only case in group 2 with this complication occurred after device-assisted compression and did not require surgical correction. Despite the absence of statistically significant differences among the types of hemostasis, we believe that surgical repair of the vessel is an excellent option for patients submitted to covered stent implantation who need bulkier long sheaths to be inserted, mainly older children and adolescents with small femoral arteries. The increasing number of surgical hemostasis seen in this study reflects the aggressive measures of our institution in the last years to avoid the incidence of access-related complications.
FOLLOW-UP
The incidence of reintervention due to restenosis was similar among both groups and to that described in literature 4.
Some risk factors for reintervention can be identified if we consider the whole sample. Multivariable analysis using Cox proportional hazard regression analysis showed that the presence of complex lesions, the use of balloon < 14mm of diameter and residual gradient >
