Dual platelet antiaggregation therapy after myocardial revascularization surgery

SUMMARY Coronary artery bypass graft (CABG) is a consolidated treatment in patients with coronary artery disease (CAD) for both symptom control and improvement of prognosis. The patency of venous grafts is still the most vulnerable point of the surgical treatment since it presents a high prevalence of occlusion both in the immediate postoperative period and in the long-term follow-up. Aspirin plays a well-established role in this setting, and for a long time, clopidogrel use has been restricted to patients allergic to aspirin. Recently, subgroup analyses of studies with different anti-platelet therapies have shown reduced mortality and cardiovascular events in patients on dual anti-platelet antiplatelet therapy (DAPT) undergoing CABG, although such studies have not been designed to evaluate this patient profile. However, there is still an insufficient number of randomized studies using DAPT in this context, resulting in a disagreement between the European and American cardiology societies guidelines regarding their indication and generating doubts in clinical practice.

RESUMO A cirurgia de revascularização miocárdica (CRM) é tratamento fundamental em pacientes com doença arterial coronariana (DAC) tanto para controle de sintomas quanto para melhora do prognóstico. A patência dos enxertos venosos ainda hoje é o ponto mais vulnerável do tratamento cirúrgico, por apresentar alta prevalência de oclusão tanto no pós-operatório imediato como no seguimento em longo prazo. A aspirina tem papel bem estabelecido neste cenário e, por muito tempo, o uso do clopidogrel ficou restrito a pacientes alérgicos a aspirina. Recentemente, análises de subgrupos de estudos com diferentes terapias antiplaquetárias demonstraram redução de mortalidade e eventos cardiovasculares em pacientes em uso de dupla antiagregação plaquetária (Dapt) submetidos à CRM, ainda que tais estudos não tenham sido desenhados para avaliar este perfil de pacientes. Contudo, há ainda uma quantidade insuficiente de estudos randomizados com uso de Dapt nesse contexto, resultando em uma discordância entre as diretrizes europeia e americana de cardiologia quanto à sua indicação e gerando dúvidas na prática clínica.

Rapamycin Combined with α-Cyanoacrylate Contributes to Inhibiting Intimal Hyperplasia in Rat Models / Rapamicina em Combinação com α-Cianoacrilato Contribui à Inibição de Hiperplasia Intimal em Modelos em Ratos

Abstract Background: Vein graft restenosis has an adverse impact on bridge vessel circulation and patient prognosis after coronary artery bypass grafting. Objectives: We used the extravascular supporter α-cyanoacrylate (α-CA), the local application rapamycin/sirolimus (RPM), and a combination of the two (α-CA-RPM) in rat models of autogenous vein graft to stimulate vein graft change. The aim of our study was to observe the effect of α-CA, RPM, and α-CA-RPM on vein hyperplasia. Methods: Fifty healthy Sprague Dawley (SD) rats were randomized into the following 5 groups: sham, control, α-CA, RPM, and α-CA-RPM. Operating procedure as subsequently described was used to build models of grafted rat jugular vein on carotid artery on one side. The level of endothelin-1 (ET-1) was determined by enzyme-linked immunosorbent assay (ELISA). Grafted veins were observed via naked eye 4 weeks later; fresh veins were observed via microscope and image-processing software in hematoxylin-eosin (HE) staining and immunohistochemistry after having been fixed and stored" (i.e. First they were fixed and stored, and second they were observed); α-Smooth Muscle Actin (αSMA) and von Willebrand factor (vWF) were measured with reverse transcription-polymerase chain reaction (RT-PCR). Comparisons were made with single-factor analysis of variance and Fisher's least significant difference test, with p < 0.05 considered significant. Results: We found that intimal thickness of the α-CA, RPM, and α-CA-RPM groups was lower than that of the control group (p < 0.01), and the thickness of the α-CA-RPM group was notably lower than that of the α-CA and RPM groups (p < 0.05). Conclusion: RPM combined with α-CA contributes to inhibiting intimal hyperplasia in rat models and is more effective for vascular patency than individual use of either α-CA or RPM.

Resumo Fundamento: Reestenose de enxertos venosos tem um impacto adverso na circulação de pontagens e no prognóstico de pacientes após a cirurgia de revascularização miocárdica. Objetivos: Nós utilizamos α-cianoacrilato (α-CA) como suporte extravascular, rapamicina/sirolimus (RPM) como aplicação local e a combinação dos dois (α-CA-RPM) em modelos de enxerto venoso autógeno em ratos para estimular mudança no enxerto venoso. O objetivo do nosso estudo foi observar o efeito de α-CA, RPM e α-CA-RPM na hiperplasia venosa. Métodos: Cinquenta ratos Sprague Dawley (SD) saudáveis foram randomizados nos 5 grupos seguintes: sham, controle, α-CA, RPM e α-CA-RPM. O procedimento operacional descrito subsequentemente foi utilizado para construir modelos de enxertos da veia jugular na artéria carótida em ratos, em um lado. O nível de endotelina-1 (ET-1) foi determinado por ensaio de imunoabsorção enzimática (ELISA). As veias enxertadas foram observadas a olho nu 4 semanas após; as veias frescas foram observadas via microscópio e software de processamento de imagem com coloração hematoxilina-eosina (HE) e imuno-histoquímica depois de serem fixadas e armazenadas; α-actina do músculo liso (αSMA) e o fator de von Willebrand (vWF) foram medidos com reação em cadeia da polimerase-transcriptase reversa (RT-PCR). Realizaram-se as comparações com análise de variância de fator único (ANOVA) e o teste de diferença mínima significativa (LSD) de Fisher, com p < 0,05 sendo considerado estatisticamente significante. Resultados: Nós achamos que a espessura intimal nos grupos α-CA, RPM e α-CA-RPM era menor que no grupo controle (p < 0,01) e a espessura no grupo α-CA-RPM era notavelmente menor que nos grupos α-CA e RPM (p < 0,05). Conclusão: A combinação de RPM e α-CA contribui à inibição de hiperplasia em modelos em ratos e é mais efetivo para patência vascular que uso individual de α-CA ou RPM.

An overview of modern embolic protection in percutaneous coronary intervention.

Coronary embolism due to atherosclerotic debris is a rather common cause of post-procedural complications. While evidence has shown that both arteriolar vasodilators and platelet glycoprotein inhibitors have proven ineffective against post- and peri-procedural embolism,5 mechanical interventional devices have been shown to improve (lower) 30-day MACE rates. These interventions include distal filtration, distal, and proximal occlusion balloons. The distal occlusion balloon was the first approach to embolic protection. The intervention involves placement of a low pressure (<2 atm) balloon distal to the lesion of interest. Antegrade flow is temporarily interrupted while the lesion is treated. Mounted on conventional 0.014-inch guidewire shafts, distal filtration systems follow a similar intervention method to distal occlusion. In this proceeding, a delivery/recovery sheath catheter deploys an expandable filter device approximating the lumen, which is later removed following PTCA or stent placement in retroversion. The variety of existing, rather novel filter designs typically feature a wire mounted umbrella-type filter consisting of laser-drilled micropores design varied, averaging approximately 100 microm. The primary benefit derived of distal filtration includes the trivial uninterruption of antegrade flow. Unlike distal occlusion, proximal devices allow for vessel protection before lesion crossing, a great advantage in cases involving thrombosis, vulnerable plaque, or primary unstable angina. Proximal occlusion follows a nearly identical implementation as distal occlusion. While substantial research is still needed, interventionalists are advised to always use embolic protection devices in SVG interventions.

Efficacy of PercuSurge in acute myocardial infarction patients undergoing revascularization with a special emphasis on procedural time.

AIM: To evaluate the efficacy of the PercuSurge Guardwire(R) Plus Temporary Occlusion and Aspiration System, the actual procedural time involved and long-term follow-up in acute MI patients undergoing primary/rescue percutaneous coronary intervention (PCI). METHODS & RESULTS: It was a single centred, prospective study in 67 prospective AMI patients undergoing PCI. They were divided randomly into two groups depending on whether PercuSurge was used (n=30) or not used (control n=37) during PCI. Final TIMI flow, TMP grade and the time involved in or necessary for various steps of the PCI were recorded. PercuSurge showed significantly greater achievement of TIMI III flow and TMP III grade (p<0.01). Its use was associated with less total procedural time (p<0.05). The time required from guidewire crossing to stent placement; from guidewire crossing to TIMI III flow and from predilatation/stent placement to optimal TIMI flow was significantly reduced with its use (p<0.05 for all). Slow/no-reflow was significantly reduced (p<0.001), thus reducing intracoronary vasodilators and GP IIb/IIIa antagonists requirements. A 2 years' follow-up revealed four deaths in control and one death in PercuSurge group. CONCLUSION: PercuSurge reduced the total procedural time with better and faster optimal TIMI flow and TMP grade in primary/rescue PCI and was associated with less long term events.

Avaliação do leito arterial distal em revascularização de membros inferiores: estudo comparativo entre ecografia-doppler, arteriografia e medidas diretas do fluxo no intra-operatório / Arterial distal bed evaluation in revascularization of the lower extremities: comparative study enter doppler echography, arteriography and intra operative direct measures flow

A cirurgia de restauração circulatória aterial no paciente portador de isquemia crítica de membros inferiores apresenta indicações clínicas e técnica operatória já bastante estudadas e definidas. Ainda hoje, no entanto, um considerável número de enxertos evolui para oclusão. Entre as causas relacionadas à falência precoce, podemos destacar a resistência do leito distal receptor do enxerto. Interessou-nos estudar a existência de correlação hemodinâmica entre a Ecografia-Dopller, a Arteriografia pré-operatória e medidas diretas intra-operatórias de resistência do leito arterial receptor de enxerto. Foram estudadas 68 operações de revascularização de membros inferiores portadores de isquemia crítica . A Ecografia-Dopller foi considerada tenicamente satisfatória em 93,2%. Foi verificada a presença de correlação hemodinâmica positiva entre os métodos descritos acima (Teste de Pearson), particularmente para artéria a ser revascularizada pode auxiliar no estudo hemodinâmico do leito arterial receptor do enxerto e dessa forma auxiliar na definição do prognóstico do enxerto e no estabelecimento da melhor estratégia terapêutica a ser tomada ainda no período pré-operatório.

Prevención de reestenosis post implante de stents coronarios / The restenosis prevention post coronary stent implantation

Los stent coronarios fueron grandes optimizadores de la angioplastia coronaria con balón. Los estudios stress, benestent 1 y 2 evidenciaron reducciones importantes en las tasas de reestenosis coronaria. El proceso de reestenosis fue afectado por los stents en el sentido de reducir el retroceso elástico precoz y el remodelamiento negativo, pero el proceso de hiperplasia neoíntimal sólo no fue modificado sino que exagerado. En el sentido de minimizar la hiperplasia debemos establecer formas de reducir la injuria durante el implante del stent, reducir el proceso inflamatorio, inhibir la migración y proliferación celular y favorecer el proceso de endotelización del stent. Varias opciones farmacológicas han sido discutidas y presentaremos los resultados con dichas drogas tales como: actinomocina, tacrolimus, taxol y sirolimus

Aterectomía coronaria: rol actual / Endovascular coronary atherectomy: present role

La aterectomía coronaria endovascular representa a un conjunto de técnicas de remoción de placa que fueron altamente utilizadas durante la angioplastia previo a la introducción de stents. En esa época, aunque comparadas con la angioplastia con balón no ofrecían beneficio en cuanto a la incidencia de reestenosis, permitían un procedimiento más seguro que el tratamiento de las lesiones complejas. Sin embargo, posterior al advenimiento de los stents su uso se restringió a situaciones exepcionales. En los últimos años nuevamente se plantea un rol de la aterectomía para ser usada previa al implante de los stents, con el propósito de disminuir la incidencia de reestenosis. Los resultados de los estudios preliminares hasta ahora disponibles sugieren que si bien esta tecnología puede no ser necesaria en la mayoría de los casos, frente a la dilatación de placas seleccionadas que tienen una conocida mayor incidencia de reestenosis, podría ser útil la aterectomía previa al implante de los stents

Intravascular brachytherapy: a model for the calculation of the dose

In this study we present the radiation dose distribution for a theoretical model with Montecarlo simulation, and based on an experimental model developed for the study of the prevention of restenosis post-angioplasty employing intravascular brachytherapy. In the experimental in vivo model, the atherosclerotic plaques were induced in femoral arteries of male New Zealand rabbits through surgical intervention and later administration of cholesterol enriched diet. For the intravascular irradiation we employed a 32P source contained within the balloon used for the angioplasty. The radiation dose distributions were calculated using the Monte Carlo code MCNP4B according to a segment of a simulated artery. We studied the radiation dose distribution in the axial and radial directions for different thickness of the atherosclerotic plaques. The results will be correlated with the biologic effects observed by means of histological analysis of the irradiated arteries

Effectiveness of clopidogrel and aspirin versus ticlopidine and aspirin after coronary stent implantation: 1 and 6-month follow-up.

BACKGROUND: Clopidogrel is a new thienopyridine derivative and has less serious hematologic complications. We investigated the efficacy of clopidogrel plus aspirin (CA) in stent thrombosis prevention compared with ticlopidine plus aspirin (TA). METHOD AND RESULTS: Sixty-eight patients who underwent coronary stenting were randomized into 2 groups: TA group, n = 31 and CA group, n = 37. At 1 month, there were 3 major bleeding complications, 2 in the CA group and 1 in the TA group. Neither stent thrombosis nor hematologic events were found in both groups. Two patients in the TA group died, 1 from sudden death and another from tracheal stenosis. At 6 months, five patients developed in-stent restenosis, 4 in the CA group and 1 in the TA group, p = NS. One patient in each group had acute coronary syndrome. CONCLUSION: Clopidogrel plus aspirin is an effective coronary stenting regimen comparable to ticlopidine plus aspirin.