Instituto do Coração do Hospital das Clínicas – FMUSP, São Paulo, SP
Resultados animadores sobre o prognóstico em curto ou longo prazo da cirurgia de revascularização miocárdica (RCM) são atribuídos à aplicação de um maior número de enxertos nas artérias coronarianas1. Para se alcançar esse objetivo, é necessário que as artérias nativas tenham um calibre adequado para receber o enxerto, que a placa aterosclerótica seja proximal e que o leito distal da artéria permita bom fluxo. Além disso, na estratégia cirúrgica, as opções de revascularizar sub-ramos arteriais e também artérias ocluídas deverão ser consideradas para intervenção.
A cirurgia realizada, nessas condições, recebe o nome de revascularização anatômica completa, na qual todos os vasos a serem tratados devam ter diâmetros > 1,5 mm e estenose luminar
A hipotética superioridade da cirurgia não transferiu, entretanto, benefícios concretos para determinado grupo de pacientes3. Com recentes avanços no uso de enxertos arteriais para RCM e
Na prática médica contemporânea, contudo, o médico encontra varias opções disponíveis na grande maioria dos casos. Todavia, assistimos a uma falta de resultados consistentes para escolher a melhor opção para revascularizar o miocárdio. As atuais diretrizes disponíveis para tratamento da doença multiarterial coronariana (DAC) não discutem formalmente essa questão6,7. Nesse contexto, a decisão de aplicar uma revascularização miocárdica completa ou não depende das condições que cada paciente apresenta, cujo julgamento é feito quase sempre durante a intervenção cirúrgica.
O mesmo dilema é vivido pelo cardiologista intervencionista durante procedimentos com pacientes portadores de DAC estável ou em presença de síndrome isquêmica aguda. Nessa última condição, a preferência do operador está focada quase sempre no vaso relacionado ao evento. Assim, a estratégia da revascularização percutânea completa depende da condição do paciente, do local das estenoses, da qualidade e do diâmetro do vaso. Nesse contexto, a probabilidade de ocorrer uma revascularização percutânea incompleta será maior que na RCM.
Estudos randomizados que objetivaram comparar a relativa eficácia da RCM sobre a PCI concluíram que a intervenção percutânea não diminuiu a taxa de mortalidade encontrada na cirurgia; além disso, revelaram expressiva necessidade de novas intervenções percutaneas8-12. Nesses estudos, o número de intervenções percutâneas foi significativamente menor que o número de enxertos aplicados nos pacientes. Além disso, cabe aqui salientar que, com exceção do estudo MASS II, todos os outros estudos utilizaram amostras predominantemente biarteriais cujo prognóstico clínico é admitido como bastante favorável (
Considerando que o número menor de intervenções percutâneas não teve reflexos na mortalidade imediata ou tardia nesses estudos comparativos, é licito questionar sobre se o número aumentado de enxertos tem real implicação no prognóstico da enfermidade. Para ambas as estratégias, PCI ou RCM, existe ainda substancial incerteza sobre uma definição, e também, sobre a mais adequada forma de revascularizar o miocárdio. Teoricamente, a revascularização completa do miocárdio para qualquer estratégia deveria agregar benefícios adicionais relacionados à recuperação da função miocárdica, ou à proteção de futuros eventos, traduzindo assim melhor sobrevivência. Isso resultaria, entretanto, num prolongado tempo de procedimento e alto risco imediato de complicações. Dessa forma, a decisão sobre a melhor forma de revascularizar o miocárdio ainda depende da correta avaliação individualizada do médico.
Avanços na técnica de revascularização cirúrgica do miocárdio têm permitido que pacientes recebam enxertos arteriais ou venosos sem auxilio de circulação extracorpórea. Esse procedimento tem, entretanto, limitações técnicas relativas a aplicações de enxertos em artérias localizadas na parede posterior do ventrículo esquerdo, impondo, assim, a realização de menor número de anastomoses. Essa condição sinaliza possibilidade real de revascularização incompleta do miocárdio. Isso não parece, entretanto, contribuir para um pior prognóstico em curto prazo nesses pacientes, quando comparados com aqueles que receberam maior número de enxertos com auxílio da circulação extracorpórea13-14 (
Cabe salientar, contudo, que mesmo revelando uma redução no número de eventos perioperatórios, a cirurgia de revascularização sem o auxílio da CEC impôs uma redução na perviabilidade dos enxertos em curto prazo, de maneira significativa (88%
Estudos prévios e também recentes, comparando o tratamento clínico com as formas habituais de revascularização, têm revelado que, baseados em rigoroso controle dos fatores de risco e em medicação apropriada, o tratamento clínico tem a mesma eficácia na prevenção da morte que RCM ou PCI, independentemente do número de intervenções percutâneas ou do número de enxertos aplicados em determinados subgrupos de pacientes8,15 (
Pacientes diabéticos considerados como de potencial risco aumentado de pior prognóstico foram avaliados em vários ensaios comparando RCM e PCI9,16. O melhor prognóstico em dez anos de sobrevivência em pacientes submetidos a RCM comparados com PCI (60%
Há ainda controvérsias se a revascularização, completa ou não, oferece melhor prognóstico em pacientes idosos, ainda que eles estejam expostos a um aumento de mortalidade relacionado ao procedimento19. Entre 5.003 pacientes com idade
Teoricamente, o tamanho da área revascularizada alcançada por RCM ou PCI é o maior determinante da sobrevivência de pacientes com DAC. Baseado em evidências disponíveis, a revascularização por meio de RCM ou PCI oferece benefícios similares em relação à sobrevivência; entretanto, a intervenção deverá ser pelo menos funcionalmente completa em pacientes com DAC estável, multiarterial com função ventricular preservada, e não-diabéticos. Contemporaneamente, a angioplastia coronária tem ampla preferência pelos médicos em razão de maior aceitação pelos pacientes e de reduzido tempo de internação hospitalar. Ainda que dados atuais relatem que PCI impõe riscos de subseqüentes intervenções em razão de reestenoses, o uso de novas próteses endoarteriais é extremamente promissor na redução desses riscos.
Condições clínicas devem nortear a escolha por uma completa ou incompleta revascularização diante de subgrupos específicos de pacientes. Os pacientes diabéticos têm maiores benefícios com a revascularização completa com RCM. De maneira contrária, em pacientes com síndrome coronariana aguda, uma incompleta revascularização por meio de PCI na artéria relacionada ao evento é muito efetiva quando realizada em tempo hábil. Entretanto, sendo a PCI um potencial indutor de reintervenções, e a RCM reservada prioritariamente para pacientes sintomáticos, é permitido colocar o tratamento medicamentoso, associado a um rigoroso controle dos fatores de risco, como uma opção terapêutica razoável para pacientes com DAC estável pouco sintomático e com função ventricular preservada, como primeira opção em pacientes que recusam o tratamento intervencionista; PCI ou RCM.
1. Hemingway H, Crock AM, Feder G, et al. Underuse of coronary revascularization procedures in patients considered appropriate candidates for revascularization Engl J Med. 2001;344:645-54.
2. Zamarino M, Calafiori AM, Caterina R. Complete Myocardial Revascularization: Between Myth and Reality. Eur Heart J. 2005;26:1824-30.
3. Hoffman SN, TenBrook JA, Wolf MP, et al. A meta-analysis of randomized controlled trials comparing coronary artery bypass graft with percutaneous transluminal coronary angioplasty: one- to eight-year outcomes. J Am Coll Cardiol. 2003;41:1293-304.
4. PW, Unger F, Sousa JE, et al. Comparison of coronary-artery bypass surgery and stenting for the treatment of multivessel disease. N Engl J Med. 2001;344:1117-24.
5. Legrand VM, Serruys PW, Unger F, et al. Three-year outcome after coronary stenting versus bypass surgery for the treatment of multivessel disease. Arterial Revascularization Therapy Study (ARTS) Investigators. Circulation. 2004;109:1114-20.
6. Smith SC Jr, Dove JT, Jacobs AK, et al. ACC/ AHA guidelines for percutaneous coronary angioplasty: a report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1993 Guidelines for Percutaneous Transluminal Coronary Angioplasty). J Am ColI Cardiol. 2001;37:2239i-lxvi.
7. Eagle KA, Guyton RA, Davidoff R, et al. ACC/ AHA 2004 guideline update for coronary artery bypass graft surgery: a report of the American College Df Cardiology / American Heart Association Task Force on Practice Guidelines (Committee to Update the 1999 Guidelines for Coronary Artery Bypass Graft Surgery). Circulation. 2004;110:e340-e437.
8. Hueb W, Soares PR, Gersh BJ, et al. The Medicine, Angioplasty, or Surgery Study (MASS-II): a Randomized Controlled Clinical Trial of 3 Therapeutic Strategies for Multi-vessel Coronary Artery Disease: 1-Year Results. Jam Coll Cardiol. 2004; 43:1743-51.
9. The Bypass Angioplasty Revascularization Investigators (BARI). Comparison of coronary bypass surgery with angioplasty in patients with multi-vessel disease. N Engl J Med. 1996;335:217-25.
10. CABRI Trial Participants. First-year results of CABRI (Coronary Angioplasty versus Bypass Revascularization Investigation). Lancet. 1995;346:1179-84. CABRI
11. The SoS Investigators. Coronary artery bypass surgery versus percutaneous coronary angioplasty with stent implantation in patients with multivessel coronary artery disease (the Stent or Surgery trial): a randomized controlled trial. Lancet. 2002;360:965-70.
12. Hamm CW, Reimers J, Ischinger T, Rupprecht HJ, Berger J, Bleifeld W. A randomized study of coronary angioplasty compared with bypass surgery in patients with symptomatic multivessel coronary disease. German Angioplasty Bypass Surgery Investigation. N Engl J Med. 1994;331:1037-43.
13. Straka Z, Widimski P, Jirasek K, et al. Off-pump versus on-pump coronary surgery: final results from a prospective randomized study PRAGUE-4. Ann Thorac Surg.2004;77:789-93.
14. Widimski P, Straka Z Stros P, et al. One-year coronary bypass patency. A randomized comparison between off-pump and on-pump surgery. Angiografic results. Circulation. 2004;110:3418-23.
15. Hueb W, Bellotti G, Ramires JAF, Da Luz PL, Pilleggi F. Two-to eight-year survival rates in patients who refused coronary artery bypass grafting. Am J Cardiol. 1989;63:155-9.
16. Serruys PW, Unger F, Souza JE, et al. Comparisson of coronary-artery bypass surgery and stenting for the treatment of multivessel disease. N Engl J Med. 2001;344:1117-24.
17. O'Keefe JH, Blackstone EH, Sergeant P, et al. The optimal mode of coronary revascularization for diabetics. A risk-adjusted long-term study comparing coronary angioplasty and coronary bypass surgery. Eur Heart J. 1998;19:1696-703.
18. Rozenman Y, Sapoznikov D, Mosseri M, et al. Long-term angiographic follow-up of coronary balloon angioplasty in patients with diabetes mellitus: a clue to the explanation of the results of the BAR I study. Balloon Angioplasty Revascularization Investigation. J Am Coll Cordial. 1997;30:1420-5.
19. Graham MM, Ghali WA, Faris PD, et al. Survival after coronary revascularization in the elderly. Circulation. 2002;105:2378-84.
20. Osswald BR, Tochtermann U, Schweiger P, et al. Does the completeness of revascularization contribute to an improved early survival in patients up to 70 years of age? Thorac Cardiovasc Surg. 2001;49:373-7.
Whady Armindo Hueb Rua Araucária, 677 02338-010 – São Paulo, SP E-mail:
Recebido em 11/04/06
Aceito em 24/04/06
Instituto do Coração do Hospital das Clínicas – FMUSP, São Paulo, SP - Brazil
Encouraging results in the short- or long-term prognosis of myocardial revascularization surgery (MRS) may be attributed to the use of a larger number of grafts in coronary arteries1. To reach this goal, native arteries need to have an adequate diameter to receive the graft, the atherosclerotic plaque has to be proximal and the distal arterial bed should allow good blood flow. Furthermore, in surgical strategy, options to revascularize arterial branches and occluded arteries should also be considered. Surgery done under such conditions is named complete anatomical revascularization, where every blood vessel to be treated should have a diameter over 1.5mm and lumen stenosis over 50%, regardless of downstream myocardial viability. Complete functional revascularization is also the situation in which only arteries that irrigate viable myocardium are surgically approached. When the surgical procedure does not treat every artery with stenosis over 50% in a viable myocardium, the operation is named incomplete but still functional revascularization2.
The hypothetical superiority of surgery has not resulted in true benefits for a specific group of patients3. Recent developments in the use of arterial grafts for MRS and stents for coronary angioplasty (PCI) have led to improved results in both strategies. Widespread pharmacological use of statins and antiplatelet drugs have improved the outcome in candidate patients for MRS or PCI, with little difference between both procedures except for more favorable results in non-fatal myocardial infarction prevention surgery and when a second intervention is required4,5.
On the other hand, in current medical practice, physicians have a variety of options available in most cases. However, there is a lack of consistent results to support the choice of the best procedure to revascularize the myocardium. Current available guidelines for the treatment of coronary multivessel disease do not formally address this issue6,7. In this context, the decision to apply complete or incomplete myocardial revascularization depends on the clinical condition of each patient and is made almost always during the surgical procedure. The interventionist cardiologist also faces the same dilemma in procedures on patients with stable coronary artery disease (CAD) or when acute ischemic syndrome is also present. In this situation the preference of the surgeon is almost always focused on the blood vessel related to the clinical event. Thus, the strategy of complete percutaneous revascularization depends on the patient's clinical condition, the site of stenosis, and the quality and diameter of the blood vessel. Hence, the probability that incomplete percutaneous revascularization will be done is higher in PCI when compared to MRS.
Randomized studies comparing the relative efficacy of MRS over PCI concluded that percutaneous angioplasty did not reduce the mortality rate of surgery; furthermore, the study disclosed a significant need for further percutaneous angioplasty8-12. In these studies the number of percutaneous angioplasty was significantly lower compared to the number of graft surgeries. It should be emphasized that, except for the MASS II trial, all other studies used predominantly double artery samples, which have a good clinical prognosis (
Given that a lower number of percutaneous angioplasty did not affect immediate or late mortality in these comparative studies, it is fair to inquire whether more grafts have a true effect on the prognosis. There is still significant uncertainty in the decision for each of the procedures (PCI or MRS), as well as for the most adequate form of myocardial revascularization. Theoretically, any strategy of complete myocardial revascularization should add extra benefits to myocardial function recovery or protection against future events, which could increase survival rates. However, this could also increase the procedure time and the risk of short-term complications. Therefore the best decision to revascularize the myocardium still depends on correct individualized medical assessment.
Advances in myocardial revascularization surgery techniques have allowed patients to receive arterial or venous grafts with no need for extra-corporeal circulation. This option, however, has technical limits when grafts are applied to the left ventricle posterior wall, which means fewer bypasses and more frequent incomplete myocardial revascularization. Apparently, however, this does not worsen the short-term prognosis for these patients as compared to those that received more grafts with help from extra-corporeal circulation13,14 (
A further point is that even with fewer perioperative events, revascularization surgery without extra-corporeal circulation resulted in significantly decreased short term graft patency (88%
Previous trials and other recent studies compared medical treatment with usual revascularization methods, and revealed that, based on a strict control of risk factors and appropriate medication, medical treatment has similar efficacy in reducing death compared to MRS or PCI regardless of the number of percutaneous angioplasties or the number of grafts applied to specific patient subgroups8,15 (
Diabetic patients admitted as potentially having an increased risk for worse prognosis were assessed in a number of trials comparing MRS and PCI9,16. The best 10-year survival prognosis in patients undergoing MRS compared to PCI (60%
There are still controversies about whether complete or incomplete revascularization offers better results in elderly patients, particularly as this group has a higher procedure-related mortality19. In a group of 5.003 patients aged over 70 years, incomplete revascularization was recognized as an independent risk factor for early death and death six months after the procedure20. In patients with reduced survival expectancy, complete revascularization can increase immediate procedure-related risks, which should be weighed strongly in the hypothetic possibility of prolonged survival.
Theoretically, the size of the revascularized area using MRS or PCI is the main survival determining factor for patients with coronary artery disease. Based on available evidence, revascularization by MRS or PCI offers similar survival benefits; the intervention, however, should be at least functionally complete in patients who are non-diabetic, and have preserved left ventricle function, multivessel, and stable coronary artery disease. Coronary angioplasty is currently more popular among physicians due to increased patient acceptance and reduced hospital stay. Although current data shows that PCI tends to require further interventions due to recurring stenosis, new endo-arterial stents promise a reduction of this risk.
Clinical conditions should guide the choice of complete or incomplete revascularization in specific patient groups. Diabetic patients enjoy greater benefits with complete revascularization by MRS. On the other hand, acute coronary syndrome patients tend to benefit more from timely incomplete revascularization of the event-related artery through PCI. As PCI potentially requires further interventions, and MRS is usually reserved for symptomatic patients, medical treatment including strict control of risk factors may be a reasonable first choice of treatment for patients with few symptoms, preserved left ventricular function, stable coronary artery disease, and who refuse invasive treatment such as PCI or MRS.
1. Hemingway H, Crock AM, Feder G, et al. Underuse of coronary revascularization procedures in patients considered appropriate candidates for revascularization Engl J Med. 2001;344:645-54.
2. Zamarino M, Calafiori AM, Caterina R. Complete Myocardial Revascularization: Between Myth and Reality. Eur Heart J. 2005;26:1824-30.
3. Hoffman SN, TenBrook JA, Wolf MP, et al. A meta-analysis of randomized controlled trials comparing coronary artery bypass graft with percutaneous transluminal coronary angioplasty: one- to eight-year outcomes. J Am Coll Cardiol. 2003;41:1293-304.
4. PW, Unger F, Sousa JE, et al. Comparison of coronary-artery bypass surgery and stenting for the treatment of multivessel disease. N Engl J Med. 2001;344:1117-24.
5. Legrand VM, Serruys PW, Unger F, et al. Three-year outcome after coronary stenting versus bypass surgery for the treatment of multivessel disease. Arterial Revascularization Therapy Study (ARTS) Investigators. Circulation. 2004;109:1114-20.
6. Smith SC Jr, Dove JT, Jacobs AK, et al. ACC/ AHA guidelines for percutaneous coronary angioplasty: a report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1993 Guidelines for Percutaneous Transluminal Coronary Angioplasty). J Am ColI Cardiol. 2001;37:2239i-lxvi.
7. Eagle KA, Guyton RA, Davidoff R, et al. ACC/ AHA 2004 guideline update for coronary artery bypass graft surgery: a report of the American College Df Cardiology / American Heart Association Task Force on Practice Guidelines (Committee to Update the 1999 Guidelines for Coronary Artery Bypass Graft Surgery). Circulation. 2004;110:e340-e437.
8. Hueb W, Soares PR, Gersh BJ, et al. The Medicine, Angioplasty, or Surgery Study (MASS-II): a Randomized Controlled Clinical Trial of 3 Therapeutic Strategies for Multi-vessel Coronary Artery Disease: 1-Year Results. Jam Coll Cardiol. 2004; 43:1743-51.
9. The Bypass Angioplasty Revascularization Investigators (BARI). Comparison of coronary bypass surgery with angioplasty in patients with multi-vessel disease. N Engl J Med. 1996;335:217-25.
10. CABRI Trial Participants. First-year results of CABRI (Coronary Angioplasty versus Bypass Revascularization Investigation). Lancet. 1995;346:1179-84. CABRI
11. The SoS Investigators. Coronary artery bypass surgery versus percutaneous coronary angioplasty with stent implantation in patients with multivessel coronary artery disease (the Stent or Surgery trial): a randomized controlled trial. Lancet. 2002;360:965-70.
12. Hamm CW, Reimers J, Ischinger T, Rupprecht HJ, Berger J, Bleifeld W. A randomized study of coronary angioplasty compared with bypass surgery in patients with symptomatic multivessel coronary disease. German Angioplasty Bypass Surgery Investigation. N Engl J Med. 1994;331:1037-43.
13. Straka Z, Widimski P, Jirasek K, et al. Off-pump versus on-pump coronary surgery: final results from a prospective randomized study PRAGUE-4. Ann Thorac Surg.2004;77:789-93.
14. Widimski P, Straka Z Stros P, et al. One-year coronary bypass patency. A randomized comparison between off-pump and on-pump surgery. Angiografic results. Circulation. 2004;110:3418-23.
15. Hueb W, Bellotti G, Ramires JAF, Da Luz PL, Pilleggi F. Two-to eight-year survival rates in patients who refused coronary artery bypass grafting. Am J Cardiol. 1989;63:155-9.
16. Serruys PW, Unger F, Souza JE, et al. Comparisson of coronary-artery bypass surgery and stenting for the treatment of multivessel disease. N Engl J Med. 2001;344:1117-24.
17. O'Keefe JH, Blackstone EH, Sergeant P, et al. The optimal mode of coronary revascularization for diabetics. A risk-adjusted long-term study comparing coronary angioplasty and coronary bypass surgery. Eur Heart J. 1998;19:1696-703.
18. Rozenman Y, Sapoznikov D, Mosseri M, et al. Long-term angiographic follow-up of coronary balloon angioplasty in patients with diabetes mellitus: a clue to the explanation of the results of the BAR I study. Balloon Angioplasty Revascularization Investigation. J Am Coll Cordial. 1997;30:1420-5.
19. Graham MM, Ghali WA, Faris PD, et al. Survival after coronary revascularization in the elderly. Circulation. 2002;105:2378-84.
20. Osswald BR, Tochtermann U, Schweiger P, et al. Does the completeness of revascularization contribute to an improved early survival in patients up to 70 years of age? Thorac Cardiovasc Surg. 2001;49:373-7.
Whady Armindo Hueb Rua Araucária, 677 02338-010 – São Paulo, SP, Brazil E-mail:
Received on 04/11/06
Accepted on 04/24/06