Pathology of drug-eluting versus bare-metal stents in saphenous vein bypass graft lesions

Pathological evaluation of a fluoropolymer-based drug-eluting stent in an arteriovenous graft outflow venous stenosis

A fluoropolymer-based drug-eluting stent was implanted in an arteriovenous graft outflow venous stenosis. Two and a half years later, due to a local infection, the stent was removed surgically, and a pathological evaluation was conducted. The stent struts exhibited partial endothelial cell coverage, with the remaining surface predominantly covered by fibrin. Notably, there was no evidence of restenosis or aneurysmal change.

Single-Centre Registry Analysis of Patients Who Underwent Percutaneous Coronary Intervention on Their Coronary Bypass Grafts

Background

The study assessed the outcomes of patients undergoing percutaneous coronary intervention (PCI) to bypass grafts, focusing on all-cause mortality and target vessel failure (TVF) rates.

Methods

A single-centre registry analysis included 364 patients who underwent PCI on coronary bypass grafts between 2008 and 2019. The study analyzed all-cause mortality and TVF, which encompassed target lesion revascularization, target vessel revascularization, and medically treated occluded target graft post-PCI.

Results

The median age of the patients was 71 years (interquartile range: [IQR] 65-78), with 82.1% being male. Most patients (94.8%) received PCI on saphenous vein grafts, and the median graft age was 13.0 years (IQR: 8.4-17.6). Drug-eluting stents were used more frequently (54.4%) than bare-metal stents (45.6%), with a median stent diameter of 3.5 mm (IQR: 3-4) and length of 19 mm (IQR: 18-28). Outcome differences were not significant for PCI sites (aorto-ostial, graft body, anastomosis), use of drug-eluting stents, or use of protection devices. The 1-year mortality rate was 3.3%, whereas the combined rate of TVF or death was 20.3%. After 5 years, the mortality rate increased to 14.9%, and the combined TVF or death rate rose to 40.3%. Multivariable analyses revealed that chronic kidney disease was independently associated with mortality (hazard ratio [HR] 1.74, 95% confidence interval [CI] 1.16-2.61, P = 0.007), whereas hypertension (HR 2.42, 95% CI 1.32-4.42, P = 0.004) and increased stent length (HR 1.01, 95% CI 1.00-1.02, P = 0.007) were independently associated with the TVF-or-mortality outcome.

Conclusions

Patients undergoing PCI to bypass grafts experience considerable adverse outcomes over a 5-year period, highlighting the need for further strategies in managing this high-risk population.

Apolipoprotein A-I vascular gene therapy reduces vein-graft atherosclerosis

Coronary artery venous bypass grafts typically fail because of atherosclerosis driven by lipid and macrophage accumulation. Therapy for vein-graft atherosclerosis is limited to statin drugs, which are only modestly effective. We hypothesized that transduction of vein-graft endothelium of fat-fed rabbits with a helper-dependent adenovirus expressing apolipoprotein AI (HDAdApoAI) would reduce lipid and macrophage accumulation. Fat-fed rabbits received bilateral external jugular vein-to-carotid artery interposition grafts. Four weeks later, one graft per rabbit (n = 23 rabbits) was infused with HDAdApoAI and the contralateral graft with HDAdNull. Grafts were harvested 12 weeks later. Paired analyses of grafts were performed, with vein graft cholesterol, intimal lipid, and macrophage content as the primary endpoints. HDAd genomes were detected in all grafts. APOAI mRNA was median 63-fold higher in HDAdApoAI grafts versus HDAdNull grafts (p < 0.001). HDAdApoAI grafts had a mean 15% lower total cholesterol (by mass spectrometry; p = 0.003); mean 19% lower intimal lipid (by oil red O staining; p = 0.02); and mean 13% lower expression of the macrophage marker CD68 (by reverse transcriptase-mediated quantitative PCR; p = 0.008). In vivo transduction of vein-graft endothelium achieves persistent APOAI expression and reduces vein-graft cholesterol, intimal lipid, and CD68 expression. Vascular gene therapy with APOAI has promise for preventing vein-graft failure caused by atherosclerosis.

Pathophysiology and management of saphenous vein graft disease

INTRODUCTION

The saphenous vein graft (SVG) is the most used conduit in CABG. With standardization of its use as a conduit came an understanding of its accelerated atherosclerosis, known as saphenous vein graft disease (SVGD). Given its extensive use, a review of the pathophysiology and management of SVGD is important as we optimize its use.

AREAS COVERED

For this review, an extensive literature search was completed to identify and examine the evolution of SVG in CABG, mechanisms driving SVGD, and methods developed to prevent and manage it. This includes a review of relevant major papers and trials in this space.

EXPERT OPINION

Eras of evolution in SVG usage in CABG include an experimental era, era of SVG dominance in CABG, and the current era of mixed venous and arterial grafting. As SVGD was studied, the mechanisms behind it became more understood, and prevention and management methods were developed. As advances in surgical techniques and pharmacotherapy continue to reduce occurrence and severity of SVGD, long-term patency of SV grafts continues to improve and remain excellent in optimized settings. With continued innovation and improvement in operative techniques, the SVG conduit is and will remain an important player in the field of coronary bypass.

Acute Mechanical Consequences of Vessel-Specific Coronary Bypass Combinations

PURPOSE

Premature coronary artery bypass graft (CABG) failure has been linked to geometric, mechanical, and compositional discrepancies between host and graft tissues. Acute hemodynamic disturbances and the introduction of wall stress gradients trigger a myriad of mechanobiological processes at the anastomosis that can be associated with restenosis and graft failure. Although the origins of coronary artery disease dictate the anastomotic target, an opportunity exists for graft-vessel optimization through rationale graft selection.

METHODS

Here we explored the four distinct regions of the left (L) and right (R) ITA (1 = proximal, 2 = submuscular, 3 = middle, 4 = distal), and four common target vessels in the coronary circulation including the proximal and distal left anterior descending (PLAD & DLAD), right coronary (RCA), and left circumflex (LCX) arteries. Benchtop biaxial mechanical data was used to acquire constitutive model parameters of these tissues and enable vessel-specific computational models to elucidate the mechanical consequences of 32 unique graft-target combinations.

RESULTS

Simulations revealed the maximum principal wall stresses for the PLAD, RCA, and LCX occurred when anastomosed with LITA1, and the maximum flow-induced shear stress occurred with LITA4. The DLAD, on the other hand, reached stress maximums when anastomosed to LITA4. Using a normalized objective function of simulation output variables, we found LITA2 to be the best graft choice for both LADs, RITA3 for the RCA, and LITA3 for the LCX.

CONCLUSION

Although mechanical compatibility is just one of many factors determining bypass graft outcomes, our data suggests improvements can be made to the grafting process through vessel-specific regional optimization.

Clinical results of everolimus-eluting stents and sirolimus-eluting stents in patients undergoing percutaneous coronary intervention

Background

It has been pronounced that everolimus-eluting stent (EES) had lower charge of goal-lesion revascularization and stent thrombosis as compared with sirolimus-eluting stents (SES).The goal of this observation was to compare the efficacy and protection of EES with SES in primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI).

Methods

In this retrospective study, a total of 404 patients with coronary artery stenosis who underwent angioplasty of one or more coronary arteries were included in the study. Of these, 202 were treated with SES and the others with EES. The data were collected by a questionnaire through which the annual incidence of coronary stent complications including the occurrence of stent thrombosis (confirmed by re-angiography), the occurrence of acute coronary syndrome leading to hospitalization, the occurrence of vascular myocardial infarction related to the stenting vessel, the need for re-angiography and angioplasty and finally the incidence of cardiac mortality were evaluated.

Results

This study showed that the odds ratio of EES thrombosis to SES stent in the unadjusted model is 1.01 (0.06-16.34) and in the adjusted model for confounding variables was equal to 0.80 (0.04-13.35) which in both models, these values were not statistically significant.

Conclusion

The findings of the present study indicate that there is no statistically significant difference between the outcomes in the two groups treated with SES and EES release stents.

Jha P, Lupieri A, Nakano T, Passos LS, Rogers MA, Becker-Greene D, Le TD, Decano JL, Ho Lee L, Guimaraes GC, Abdelhamid I, Halu A, Muscoloni A, V. Cannistraci C, Higashi H, Zhang H, Vromman A, Libby P, Keith Ozaki C, Sharma A, Singh SA, Aikawa E, Aikawa M. Proprotein Convertase Subtilisin/Kexin 9 (PCSK9) Promotes Macrophage Activation via LDL Receptor-Independent Mechanisms

BACKGROUND

Activated macrophages contribute to the pathogenesis of vascular disease. Vein graft failure is a major clinical problem with limited therapeutic options. PCSK9 (proprotein convertase subtilisin/kexin 9) increases low-density lipoprotein (LDL)-cholesterol levels via LDL receptor (LDLR) degradation. The role of PCSK9 in macrophage activation and vein graft failure is largely unknown, especially through LDLR-independent mechanisms. This study aimed to explore a novel mechanism of macrophage activation and vein graft disease induced by circulating PCSK9 in an LDLR-independent fashion.

METHODS

We used Ldlr^-/- mice to examine the LDLR-independent roles of circulating PCSK9 in experimental vein grafts. Adeno-associated virus (AAV) vector encoding a gain-of-function mutant of PCSK9 (rAAV8/D377Y-mPCSK9) induced hepatic PCSK9 overproduction. To explore novel inflammatory targets of PCSK9, we used systems biology in Ldlr^-/- mouse macrophages.

RESULTS

In Ldlr^-/- mice, AAV-PCSK9 increased circulating PCSK9, but did not change serum cholesterol and triglyceride levels. AAV-PCSK9 promoted vein graft lesion development when compared with control AAV. In vivo molecular imaging revealed that AAV-PCSK9 increased macrophage accumulation and matrix metalloproteinase activity associated with decreased fibrillar collagen, a molecular determinant of atherosclerotic plaque stability. AAV-PCSK9 induced mRNA expression of the pro-inflammatory mediators IL-1β (interleukin-1 beta), TNFα (tumor necrosis factor alpha), and MCP-1 (monocyte chemoattractant protein-1) in peritoneal macrophages underpinned by an in vitro analysis of Ldlr^-/- mouse macrophages stimulated with endotoxin-free recombinant PCSK9. A combination of unbiased global transcriptomics and new network-based hyperedge entanglement prediction analysis identified the NF-κB (nuclear factor-kappa B) signaling molecules, lectin-like oxidized LOX-1 (LDL receptor-1), and SDC4 (syndecan-4) as potential PCSK9 targets mediating pro-inflammatory responses in macrophages.

CONCLUSIONS

Circulating PCSK9 induces macrophage activation and vein graft lesion development via LDLR-independent mechanisms. PCSK9 may be a potential target for pharmacologic treatment for this unmet medical need.

Saphenous Vein Graft Intervention

Even though saphenous vein grafts (SVGs) are the most commonly used surgical conduits, their long-term patency is limited by accelerated atherosclerosis often resulting in acute coronary syndrome or asymptomatic occlusion. SVG intervention is associated with 2 significant challenges: a significant risk of distal embolization with resultant periprocedural myocardial infarction in the short-term and restenosis in the long-term. Several individual trials have compared bare metal stents with drug-eluting stents for SVG intervention. This review article discusses the pathophysiology of SVG lesions, indications for SVG intervention, and the challenges encountered, and also technical considerations for SVG intervention and the supporting evidence.

Contemporary coronary artery bypass graft surgery and subsequent percutaneous revascularization

Patients who have undergone coronary artery bypass graft (CABG) surgery are susceptible to bypass graft failure and progression of native coronary artery disease. Although the saphenous vein graft (SVG) was traditionally the most-used conduit, arterial grafts (including the left and right internal thoracic arteries and the radial artery) have improved patency rates. However, the need for secondary revascularization remains common, and percutaneous coronary intervention (PCI) has become the most common modality of secondary revascularization after CABG surgery. Procedural characteristics and clinical outcomes differ considerably from those associated with PCI in patients without previous CABG surgery, owing to altered coronary anatomy and differences in conduit pathophysiology. In particular, SVG PCI carries an increased risk of complications, and operators are shifting their focus towards embolic protection strategies and complex native-vessel interventions, increasingly using SVGs as conduits to facilitate native-vessel PCI rather than pursuing SVG PCI. In this Review, we discuss the differences in conduit pathophysiology, changes in CABG surgery techniques, and the latest evidence in terms of PCI in patients with previous CABG surgery, with a particular emphasis on safety and long-term efficacy. We explore the subject of contemporary CABG surgery and subsequent percutaneous revascularization in this complex patient population.

In-Stent Restenosis in Saphenous Vein Grafts (from the DIVA Trial)

Saphenous vein grafts (SVGs) have high rates of in-stent restenosis (ISR). We compared the baseline clinical and angiographic characteristics of patients and lesions that did develop ISR with those who did not develop ISR during a median follow-up of 2.7 years in the DIVA study (NCT01121224). We also examined the ISR types using the Mehran classification. ISR developed in 119 out of the 575 DIVA patients (21%), with similar incidence among patients with drug-eluting stents and bare-metal stents (BMS) (21% vs 21%, p = 0.957). Patients in the ISR group were younger (67 ± 7 vs 69 ± 8 years, p = 0.04) and less likely to have heart failure (27% vs 38%, p = 0.03) and SVG lesions with Thrombolysis In Myocardial Infarction 3 flow before the intervention (77% vs 83%, p <0.01), but had a higher number of target SVG lesions (1.33 ± 0.64 vs 1.16 ± 0.42, p <0.01), more stents implanted in the target SVG lesions (1.52 ± 0.80 vs 1.31 ± 0.66, p <0.01), and longer total stent length (31.37 ± 22.11 vs 25.64 ± 17.42 mm, p = 0.01). The incidence of diffuse ISR was similar in patients who received drug-eluting-stents and BMS (57% vs 54%, p = 0.94), but BMS patients were more likely to develop occlusive restenosis (17% vs 33%, p = 0.05).

Association between SYNTAX II Score and late saphenous vein graft failure in patients undergoing isolated coronary artery bypass graft surgery

OBJECTIVE

Coronary artery bypass graft (CABG) surgery is a well-established treatment modality for patients with multivessel coronary artery disease (CAD). Syntax II Score has been established as novel scoring system with better prediction of postprocedural outcomes. This study aimed to investigate the prognostic value of SYNTAX II Score for predicting late saphenous vein graft (SVG) failure in patients undergoing isolated CABG.

METHODS

The records of 1,875 consecutive patients who underwent isolated CABG with at least one SVG were investigated. Those who underwent coronary angiography and SVGs angiography at least 1 year after the CABG were included. Patients were divided into two groups based on the presence or absence of SVG failure. For each group, predictors of late SVG failure and subsequent clinical outcomes were analyzed.

RESULTS

According to this study, the presence of hypertension, higher rates of repeat revascularization, and higher SYNTAX II Scores were found to be independent predictors of late SVG failure. In addition, the prognostic value of SYNTAX II Score was found to be significantly higher than anatomical SYNTAX Score in terms of predicting late SVG failure and major adverse cardiovascular and cerebrovascular event.

CONCLUSIONS

There was a strong association between SYNTAX II Score and late SVG failure in patients undergoing isolated CABG.

Mechanisms, Prevention and Treatment of Saphenous Vein Graft Disease

Saphenous vein grafts are imperfect yet indispensable conduits commonly used for coronary artery bypass grafting. Their degeneration ultimately leading to occlusion results from the pathological response of the vein to altered blood rheology and several types of vascular injury. Surgical techniques minimizing vessel damage, and prolonged antiplatelet and lipid-lowering treatment are established methods of mitigating the degeneration process hence preventing graft occlusions. Percutaneous interventions in degenerated vein grafts carry high risk of embolization, periprocedural myocardial infarction and restenosis. Thus, native vessel should be the preferred treatment target in case of graft failure whenever technically feasible.

A Novel Risk Scoring Tool to Predict Saphenous Vein Graft Occlusion After Cardiac Artery Bypass Graft Surgery

Objectives: Coronary artery bypass grafting (CABG) success is reduced by graft occlusion. Understanding factors associated with graft occlusion may improve patient outcomes. The aim of this study was to develop a predictive risk score for saphenous vein graft (SVG) occlusion after CABG.

Methods: This retrospective cohort study enrolled 3,716 CABG patients from January 2012 to March 2013. The development cohort included 2,477 patients and the validation cohort included 1,239 patients. The baseline clinical data at index CABG was analyzed for their independent impact on graft occlusion in our study using Cox proportional hazards regression. The predictive risk scoring tool was weighted by beta coefficients from the final model. Concordance (c)-statistics and comparison of the predicted and observed probabilities of predicted risk were used for discrimination and calibration.

Results: A total of 959 (25.8%) out of 3,716 patients developed at least one late SVG occlusion. Significant risk factors for occlusion were female sex [beta coefficients (β) = 0.52], diabetes (β = 0.21), smoking (currently) (β = 0.32), hyperuricemia (β = 0.22), dyslipidemia (β = 0.52), prior percutaneous coronary intervention (PCI) (β = 0.21), a rising number of SVG (β = 0.12) and lesion vessels (β = 0.45). On-pump surgery (β = −0.46) and the use of angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) (β = −0.59) and calcium channel blockers (CCB) (β = −0.23) were protective factors. The risk scoring tool with 11 variables was developed from the derivation cohort, which delineated each patient into risk quartiles. The c-statistic for this model was 0.71 in the validation cohort.

Conclusions: An easy-to-use risk scoring tool which included female sex, diabetes, smoking, hyperuricemia, dyslipidemia, prior PCI, a rising number of SVG and lesion vessels, on-pump surgery, the use of ACEI/ ARB and CCB was developed and validated. The scoring tool accurately estimated the risk of late SVG occlusion after CABG (c-statistic = 0.71).

Saphenous Vein Graft Failure: From Pathophysiology to Prevention and Treatment Strategies

Saphenous vein grafts (SVGs) remain the most frequently used conduits in coronary artery bypass graft surgery (CABG). Despite advances in surgical techniques and pharmacotherapy, SVG failure rates remain high, often leading to repeat coronary revascularization. The no-touch SVG harvesting technique (minimal graft manipulation with preservation of vasa vasorum and nerves) reduces the risk of SVG failure, whereas the effect of the off-pump technique on SVG patency remains unclear. Use of buffered storage solutions, intraoperative graft flow measurement, careful selection of the target vessels, and physiological assessment of the native coronary circulation before CABG may also reduce the incidence of SVG failure. Perioperative aspirin and high-intensity statin administration are the cornerstones of secondary prevention after CABG. Dual antiplatelet therapy is recommended for off-pump CABG and in patients with a recent acute coronary syndrome. Intermediate (30%-60%) SVG stenoses often progress rapidly. Stenting of intermediate SVG stenoses failed to improve outcomes; hence, treatment focuses on strict control of coronary artery disease risk factors. Redo CABG is associated with higher perioperative mortality compared with percutaneous coronary intervention (PCI); hence, the latter is preferred for most patients requiring repeat revascularization after CABG. SVG PCI is limited by high rates of no-reflow and a high incidence of restenosis during follow-up. Drug-eluting and bare metal stents provide similar long-term outcomes in SVG PCI. Embolic protection devices reduce no-reflow and should be used when feasible. PCI of the corresponding native coronary artery is associated with better short- and long-term outcomes and is preferred over SVG PCI, if technically feasible.

The role of extracellular vesicles in neointima formation post vascular injury

Pathological neointimal growth can develop in patients as a result of vascular injury following percutaneous coronary intervention and coronary artery bypass grafting using autologous saphenous vein, leading to arterial or vein graft occlusion. Neointima formation driven by intimal hyperplasia occurs as a result of a complex interplay between molecular and cellular processes involving different cell types including endothelial cells, vascular smooth muscle cells and various inflammatory cells. Therefore, understanding the intercellular communication mechanisms underlying this process remains of fundamental importance in order to develop therapeutic strategies to preserve endothelial integrity and vascular health post coronary interventions. Extracellular vesicles (EVs), including microvesicles and exosomes, are membrane-bound particles secreted by cells which mediate intercellular signalling in physiological and pathophysiological states, however their role in neointima formation is not fully understood. The purification and characterization techniques currently used in the field are associated with many limitations which significantly hinder the ability to comprehensively study the role of specific EV types and make direct functional comparisons between EV subpopulations. In this review, the current knowledge focusing on EV signalling in neointima formation post vascular injury is discussed.

Targeting Smad-Mediated TGFß Pathway in Coronary Artery Bypass Graft

Revascularization surgeries such as coronary artery bypass grafting (CABG) are sometimes necessary to manage coronary heart disease (CHD). However, more than half of these surgeries fail within 10 years due to the development of intimal hyperplasia (IH) among others. The cytokine transforming growth factor-beta (TGFß) and its signaling components have been found to be upregulated in diseased or injured vessels, and to promote IH after grafting. Interventions that globally inhibit TGFß in CABG have yielded contrasting outcomes in in vitro and in vivo studies including clinical trials. With advances in molecular biology, it becomes clear that TGFß exhibits both protective and damaging roles, and only specific components such as some Smad-dependent TGFß signaling mediate vascular IH. The activin receptor-like kinase (ALK)-mediated Smad-dependent TGFß signaling pathways have been found to be activated in human vascular smooth muscle cells (VSMCs) following injury and in hyperplastic preimplantation vein grafts. It appears that focused targeting of TGFß pathway constitutes a promising therapeutic target to improve the outcome of CABG. This study dissects the role of TGFß pathway in CABG failure, with particular emphasis on the therapeutic potentials of specific targeting of Smad-dependent and ALK-mediated signaling.

The Role of Immunomodulation in Vein Graft Remodeling and Failure

Obstructive arterial disease is a major cause of morbidity and mortality in the developed world. Venous bypass graft surgery is one of the most frequently used revascularization strategies despite its considerable short and long time failure rate. Due to vessel wall remodeling, inflammation, intimal hyperplasia, and accelerated atherosclerosis, vein grafts may (ultimately) fail to revascularize tissues downstream to occlusive atherosclerotic lesions. In the past decades, little has changed in the prevention of vein graft failure (VGF) although new insights in the role of innate and adaptive immunity in VGF have emerged. In this review, we discuss the pathophysiological mechanisms underlying the development of VGF, emphasizing the role of immune response and associated factors related to VG remodeling and failure. Moreover, we discuss potential therapeutic options that can improve patency based on data from both preclinical studies and the latest clinical trials. This review contributes to the insights in the role of immunomodulation in vein graft failure in humans. We describe the effects of immune cells and related factors in early (thrombosis), intermediate (inward remodeling and intimal hyperplasia), and late (intimal hyperplasia and accelerated atherosclerosis) failure based on both preclinical (mouse) models and clinical data.

Care of the Post-CABG Patient

An estimated 400,000 coronary artery bypass graft operations are performed annually in the United States. Saphenous vein grafts are the most commonly used conduits; however, graft failure is common. In contrast, left internal mammary artery grafts have more favorable long-term patency rates. Guidelines recommend aggressive secondary prevention. In the 2 decades following surgery, 16% of patients require repeat revascularization, and percutaneous coronary intervention accounts for 98% of procedures performed. Post-coronary artery bypass graft patients presenting with symptoms of acute coronary syndrome or progressive heart failure should undergo early coronary angiography given the high likelihood that such a presentation represents graft failure. Percutaneous coronary intervention in degenerated saphenous vein grafts is associated with embolization that may cause the "no-reflow phenomenon," which can be avoided with the use of embolic protection devices. Hybrid revascularization procedures are a promising emerging strategy to avoid the placement of vein grafts.

Drug-Eluting Stents Versus Bare-Metal Stents in Saphenous Vein Graft Intervention

Background Percutaneous coronary intervention with drug-eluting stents (DES) has been increasingly used for revascularization of saphenous vein graft stenosis without strong clinical evidence favoring their use. Randomized controlled trials comparing DES versus bare-metal stents (BMS) in saphenous vein graft-percutaneous coronary intervention have been inconclusive. Methods and Results We performed a comprehensive literature search through May 15, 2018, for all eligible studies comparing DES versus BMS in patients with saphenous vein graft stenosis in PubMed, EMBASE, SCOPUS, Google Scholar, and ClinicalTrials.gov. Clinical outcomes included all-cause mortality, cardiovascular mortality, major adverse cardiovascular events, myocardial infarction, stent thrombosis, and target vessel revascularization. Six randomized controlled trials were eligible and included 1582 patients, of whom 797 received DES and 785 received BMS. The follow-up period ranged from 18 months to 60 months. There was no statistically significant difference between DES and BMS for all-cause mortality (risk ratio [RR],1.11; 95% CI, 0.0.77-1.62; P=0.57), cardiovascular mortality (RR, 1.00; 95% CI, 0.64-1.57; P=0.99), major adverse cardiovascular events (RR, 0.83; 95% CI, 0.63-1.10; P=20), target vessel revascularization (RR, 0.73; 95% CI, 0.48-1.11; P=0.14), myocardial infarction (RR, 0.74; 95% CI, 0.48-1.16; P=0.19), or stent thrombosis (RR, 1.06; 95% CI, 0.42-2.65; P=0.90). Conclusions In patients undergoing percutaneous coronary intervention for saphenous vein graft lesions, our results showed that there was no significant difference between DES and BMS for mortality, major adverse cardiovascular events, target vessel revascularization, myocardial infarction, or stent thrombosis.

Efficacy Over Time With Drug-Eluting Stents in Saphenous Vein Graft Lesions

BACKGROUND

In the ISAR-CABG (Is Drug-Eluting-Stenting Associated with Improved Results in Coronary Artery Bypass Grafts?) trial, clinical outcomes at 1 year in patients undergoing treatment of saphenous vein graft lesions were superior with drug-eluting stents (DES) versus bare-metal stents.

OBJECTIVES

The authors compared outcomes between treatment groups at 5 years.

METHODS

Patients were randomized (1:1:1:3) to receive DES (either permanent-polymer paclitaxel-eluting stents, permanent-polymer sirolimus-eluting stents, or biodegradable-polymer sirolimus-eluting stents) or bare-metal stents. The primary endpoint was the combined incidence of death, myocardial infarction (MI), or target lesion revascularization (TLR). Secondary endpoints were the composite of death or MI and TLR.

RESULTS

A total of 610 patients were allocated to treatment with DES (n = 303) or bare-metal stents (n = 307). At 5 years, the primary endpoint occurred in 159 (55.5%) versus 157 (53.6%) patients in the DES and bare-metal stent groups, respectively (hazard ratio [HR]: 0.98; 95% confidence interval [CI]: 0.79 to 1.23; p = 0.89). There was interaction between treatment effect and time (p_interaction = 0.005), with a lower event rate in the DES group at 1 year (HR: 0.64; 95% CI: 0.44 to 0.94; p = 0.02) but a numerically higher rate between 1 and 5 years (HR: 1.24; 95% CI: 0.94 to 1.63; p = 0.13). Death or MI occurred in 93 (32.8%) versus 108 (36.6%) patients, respectively (HR: 0.85; 95% CI: 0.64 to 1.12; p = 0.24), without significant interaction between treatment effect and time (p_interaction = 0.57). TLR occurred in 84 (33.1%) versus 69 (25.5%) patients in the DES and bare-metal stent groups, respectively (HR: 1.20; 95% CI: 0.87 to 1.64; p = 0.27). There was interaction between treatment effect and time (p_interaction <0.001): TLR was significantly lower in the DES group at 1 year (HR: 0.49; 95% CI: 0.28 to 0.86; p = 0.01) but significantly higher thereafter (HR: 2.02; 95% CI: 1.32 to 3.08; p = 0.001).

CONCLUSIONS

In patients undergoing treatment of saphenous vein graft lesions, the advantage of DES over bare-metal stents demonstrated at 1 year was lost at 5 years due to higher attrition of efficacy in the DES group. (Efficacy Study of Drug-Eluting and Bare Metal Stents in Bypass Graft Lesions [ISAR-CABG]; NCT00611910).

Application of virtual histological intravascular ultrasound in plaque composition assessment of saphenous vein graft diseases

OBJECTIVE

Saphenous vein grafts disease (SVGD) is a common complication after coronary artery bypass graft (CABG) and normally treated by percutaneous coronary intervention (PCI). The most common complication after SVG-PCI is slow or no-reflow. It is known that the no-reflow phenomenon occurs in up to 15% of the SVG-PCI and is associated with high risk of major adverse cardiac events (MACEs) and mortality, therefore, it is important to investigate the factors that could predict the clinical outcome of PCI for risk stratification and guiding interventions. In recent years, the spectral analysis of intravascular ultrasound (IVUS) radiofrequency data (virtual histology-IVUS [VH-IVUS]) has been used to provide quantitative assessment on both plaque compositions and morphologic characteristics.

DATA SOURCES

The PubMed, Embase, and Central databases were searched for possible relevant studies published from 1997 to 2018 using the following index keywords: "Coronary artery bypass grafting," "Saphenous venous graft disease," "Virtual histology-intravascular ultrasound," "Virtual histology-intravascular ultrasound," and "Percutaneous coronary intervention."

STUDY SELECTION

The primary references were Chinese and English articles including original studies and literature reviews, were identified and reviewed to summarize the advances in the application of VH-IVUS techniques in situ vascular and venous graft vascular lesions.

RESULTS

With different plaque components exhibiting a defined spectrum, VH-IVUS can classify atherosclerotic plaque into four types: fibrous tissue (FT), fibro fatty (FF), necrotic core (NC), and dense calcium (DC). The radiofrequency signal is mathematically transformed into a color-coded representation, including lipid, fibrous tissue, calcification, and necrotic core. Several studies have demonstrated the independent relationship between VH-IVUS-defined plaque classification or plaque composition and MACEs, but a significant association between plaque components and no-reflow after PCI in acute coronary syndrome. In recent years, VH-IVUS are applied to assess the plaque composition of SVGD, based on the similarity of pathophysiological mechanisms between coronary artery disease (CAD) and SVGD, further studies with the larger sample size, the long-term follow-up, multicenter clinical trials may be warranted to investigate the relationship between plaque composition of saphenous vein graft (SVG) by VH-IVUS and clinical outcomes in patients with SVGD undergoing PCI.

CONCLUSIONS

In degenerative SVG lesions, VH-IVUS found that plaque composition was associated with clinical features, future studies need to explore the relationship between VH-IVUS defined atherosclerotic plaque components and clinical outcomes in SVGD patients undergoing PCI, an innovative prediction tool of clinical outcomes can be created.

Drug-eluting Stents Versus Bare-metal Stents for Saphenous Vein Graft Interventions: A Systematic Review and Meta-analysis of Studies With Longer Follow-up

Randomized controlled trials comparing drug eluting stents (DES) with bare-metal stents (BMS) for saphenous vein graft (SVG) interventions have shown conflicting results. We conducted this meta-analysis to evaluate the cumulative evidence for long-term efficacy and safety of DES vs BMS in SVG lesions. A systematic search was conducted of Randomized controlled trials comparing DES vs BMS in patients undergoing percutaneous interventions for SVG lesions. End-points of interest were all-cause death, cardiac death, myocardial infarction, target lesion revascularization and target vessel revascularization at longest available follow-up. Random effects meta-analysis was conducted to estimate risk ratio with 95% confidence intervals for individual end-points. Seven studies with 1639 patients were included in the final analysis. Mean follow-up period was 32 months. Compared with BMS, DES was associated with similar risks of all-cause death (risk ratio 1.06; 95% confidence intervals 0.76-1.48) and cardiac death (0.95; 0.59-1.54). Similarly, there were no differences between DES and BMS in terms of myocardial infarction (0.81; 0.50-1.29), target vessel revascularization (0.73; 0.48-1.110 or target lesion revascularization (1.05; 0.76-1.43). Current analysis suggests no strong evidence for routine DES use in patients undergoing SVG intervention. Future studies should evaluate if SVG lesion characteristics could influence these results.

Drug-eluting stents versus bare-metal stents in saphenous vein grafts: a double-blind, randomised trial

BACKGROUND

Few studies have examined the efficacy of drug-eluting stents (DES) for reducing aortocoronary saphenous vein bypass graft (SVG) failure compared with bare-metal stents (BMS) in patients undergoing stenting of de-novo SVG lesions. We assessed the risks and benefits of the use of DES versus BMS in de-novo SVG lesions.

METHODS

Patients were recruited to our double-blind, randomised controlled trial from 25 US Department of Veterans Affairs centres. Eligible participants were aged at least 18 years and had at least one significant de-novo SVG lesion (50-99% stenosis of a 2·25-4·5 mm diameter SVG) requiring percutaneous coronary intervention with intent to use embolic protection devices. Enrolled patients were randomly assigned, in a 1:1 ratio, by phone randomisation system to receive a DES or BMS. Randomisation was stratified by presence or absence of diabetes and number of target SVG lesions requiring percutaneous coronary intervention (one or two or more) within each participating site by use of an adaptive scheme intended to balance the two stent type groups on marginal totals for the stratification factors. Patients, referring physicians, study coordinators, and outcome assessors were masked to group allocation. The primary endpoint was the 12-month incidence of target vessel failure, defined as the composite of cardiac death, target vessel myocardial infarction, or target vessel revascularisation. The DIVA trial is registered with ClinicalTrials.gov, number NCT01121224.

FINDINGS

Between Jan 1, 2012, and Dec 31, 2015, 599 patients were randomly assigned to the stent groups, and the data for 597 patients were used. The patients' mean age was 68·6 (SD 7·6) years, and 595 (>99%) patients were men. The two stent groups were similar for most baseline characteristics. At 12 months, the incidence of target vessel failure was 17% (51 of 292) in the DES group versus 19% (58 of 305) in the BMS group (adjusted hazard ratio 0·92, 95% CI 0·63-1·34, p=0·70). Between-group differences in the components of the primary endpoint, serious adverse events, or stent thrombosis were not significant. Enrolment was stopped before the revised target sample size of 762 patients was reached.

INTERPRETATION

In patients undergoing stenting of de-novo SVG lesions, no significant differences in outcomes between those receiving DES and BMS during 12 months of follow-up were found. The study results have important economic implications in countries with high DES prices such as the USA, because they suggest that the lower-cost BMS can be used in SVG lesions without compromising either safety or efficacy.

FUNDING

US Department of Veterans Affairs Cooperative Studies Program.

Inhibiting intimal hyperplasia in prosthetic vascular grafts via immobilized all-trans retinoic acid

Peripheral arterial disease is a leading cause of morbidity and mortality. The most commonly utilized prosthetic material for peripheral bypass grafting is expanded polytetrafluoroethylene (ePTFE) yet it continues to exhibit poor performance from restenosis due to neointimal hyperplasia, especially in femoral distal bypass procedures. Recently, we demonstrated that periadventitial delivery of all-trans retinoic acid (atRA) immobilized throughout porous poly(1,8 octamethylene citrate) (POC) membranes inhibited neointimal formation in a rat arterial injury model. Thus, the objective of this study was to investigate whether atRA immobilized throughout the lumen of ePTFE vascular grafts would inhibit intimal formation following arterial bypass grafting. Utilizing standard ePTFE, two types of atRA-containing ePTFE vascular grafts were fabricated and evaluated: grafts whereby all-trans retinoic acid was directly immobilized on ePTFE (atRA-ePTFE) and grafts where all-trans retinoic acid was immobilized onto ePTFE grafts coated with POC (atRA-POC-ePTFE). All grafts were characterized by SEM, HPLC, and FTIR and physical characteristics were evaluated in vitro. Modification of these grafts, did not significantly alter their physical characteristics or biocompatibility, and resulted in inhibition of intimal formation in a rat aortic bypass model, with atRA-POC-ePTFE inhibiting intimal formation at both the proximal and distal graft sections. In addition, treatment with atRA-POC-ePTFE resulted in increased graft endothelialization and decreased inflammation when compared to the other treatment groups. This work further confirms the biocompatibility and efficacy of locally delivered atRA to inhibit intimal formation in a bypass setting. Thus, atRA-POC-ePTFE grafts have the potential to improve patency rates in small diameter bypass grafts and warrant further investigation.

Inflammation in Vein Graft Disease

Bypass surgery is one of the most frequently used strategies to revascularize tissues downstream occlusive atherosclerotic lesions. For venous bypass surgery the great saphenous vein is the most commonly used vessel. Unfortunately, graft efficacy is low due to the development of vascular inflammation, intimal hyperplasia and accelerated atherosclerosis. Moreover, failure of grafts leads to significant adverse outcomes and even mortality. The last couple of decades not much has changed in the treatment of vein graft disease (VGD). However, insight is the cellular and molecular mechanisms of VGD has increased. In this review, we discuss the latest insights on VGD and the role of inflammation in this. We discuss vein graft pathophysiology including hemodynamic changes, the role of vessel wall constitutions and vascular remodeling. We show that profound systemic and local inflammatory responses, including inflammation of the perivascular fat, involve both the innate and adaptive immune system.

A Rabbit Model for Testing Helper-Dependent Adenovirus-Mediated Gene Therapy for Vein Graft Atherosclerosis

Coronary artery bypass vein grafts are a mainstay of therapy for human atherosclerosis. Unfortunately, the long-term patency of vein grafts is limited by accelerated atherosclerosis. Gene therapy, directed at the vein graft wall, is a promising approach for preventing vein graft atherosclerosis. Because helper-dependent adenovirus (HDAd) efficiently transduces grafted veins and confers long-term transgene expression, HDAd is an excellent candidate for delivery of vein graft-targeted gene therapy. We developed a model of vein graft atherosclerosis in fat-fed rabbits and demonstrated long-term (≥20 weeks) persistence of HDAd genomes after graft transduction. This model enables quantitation of vein graft hemodynamics, wall structure, lipid accumulation, cellularity, vector persistence, and inflammatory markers on a single graft. Time-course experiments identified 12 weeks after transduction as an optimal time to measure efficacy of gene therapy on the critical variables of lipid and macrophage accumulation. We also used chow-fed rabbits to test whether HDAd infusion in vein grafts promotes intimal growth and inflammation. HDAd did not increase intimal growth, but had moderate-yet significant-pro-inflammatory effects. The vein graft atherosclerosis model will be useful for testing HDAd-mediated gene therapy; however, pro-inflammatory effects of HdAd remain a concern in developing HDAd as a therapy for vein graft disease.

Plaque angiogenesis and its relation to inflammation and atherosclerotic plaque destabilization

PURPOSE OF REVIEW

The review discusses the recent literature on plaque angiogenesis and its relation to inflammation and plaque destabilization. Furthermore, it discusses how plaque angiogenesis can be used to monitor atherosclerosis and serve as a therapeutic target.

RECENT FINDINGS

Histopathologic studies have shown a clear relationship between plaque angiogenesis, intraplaque hemorrhage (IPH), plaque vulnerability, and cardiovascular events. Hypoxia is a main driver of plaque angiogenesis and the mechanism behind angiogenesis is only partly known. IPH, as the result of immature neovessels, is associated with increased influx of inflammatory cells in the plaques. Experimental models displaying certain features of human atherosclerosis such as plaque angiogenesis or IPH are developed and can contribute to unraveling the mechanism behind plaque vulnerability. New imaging techniques are established, with which plaque angiogenesis and vulnerability can be detected. Furthermore, antiangiogenic therapies in atherosclerosis gain much attention.

SUMMARY

Plaque angiogenesis, IPH, and inflammation contribute to plaque vulnerability. Histopathologic and imaging studies together with specific experimental studies have provided insights in plaque angiogenesis and plaque vulnerability. However, more extensive knowledge on the underlying mechanism is required for establishing new therapies for patients at risk.

Optical Coherence Tomography of De Novo Lesions and In-Stent Restenosis in Coronary Saphenous Vein Grafts (OCTOPUS Study)

BACKGROUND

The OCTOPUS registry prospectively evaluates the procedural and long-term outcomes of saphenous vein graft (SVG) PCI. The current study assessed the morphology of de novo lesions and in-stent restenosis (ISR) in patients undergoing PCI of SVG.

METHODS AND RESULTS

Optical coherence tomography (OCT) of SVG lesions in consecutive patients presenting with stable CAD and ACS was carried out. Thirty-nine patients (32 de novo and 10 ISR lesions) were included in the registry. ISR occurred in 5 BMS and 5 DES. There were no differences in the presence of plaque rupture and thrombus between de novo lesions and ISR. Lipid-rich tissue was identified in both de novo lesions and in ISR (75% vs. 50%, P=0.071) with a higher prevalence in BMS than in DES (23% vs. 7.5%; P=0.048). Calcific de novo lesions were detected in older grafts as compared with non-calcific atheromas (159±57 vs. 90±62 months after CABG, P=0.001). Heterogeneous neointima was found only in ISR (70% vs. 0, P<0.001) and was observed with similar frequency in both BMS and DES (24% vs. 30%, P=0.657). ISR was detected earlier in DES than BMS (median, 50 months; IQR, 18-96 months vs. 27 months; IQR, 13-29 months, P<0.001).

CONCLUSIONS

OCT-based characteristics of de novo and ISR lesions in SVG were similar except for heterogeneous tissue, which was observed only in ISR. (Circ J 2016; 80: 1804-1811).

Vein graft failure: from pathophysiology to clinical outcomes

Occlusive arterial disease is a leading cause of morbidity and mortality worldwide. Aside from balloon angioplasty, bypass graft surgery is the most commonly performed revascularization technique for occlusive arterial disease. Coronary artery bypass graft surgery is performed in patients with left main coronary artery disease and three-vessel coronary disease, whereas peripheral artery bypass graft surgery is used to treat patients with late-stage peripheral artery occlusive disease. The great saphenous veins are commonly used conduits for surgical revascularization; however, they are associated with a high failure rate. Therefore, preservation of vein graft patency is essential for long-term surgical success. With the exception of 'no-touch' techniques and lipid-lowering and antiplatelet (aspirin) therapy, no intervention has hitherto unequivocally proven to be clinically effective in preventing vein graft failure. In this Review, we describe both preclinical and clinical studies evaluating the pathophysiology underlying vein graft failure, and the latest therapeutic options to improve patency for both coronary and peripheral grafts.

Vein graft thrombi, a niche for smooth muscle cell colonization - a hypothesis to explain the asymmetry of intimal hyperplasia

Essentials Vein graft failure is the most frequent late onset complication of coronary artery bypass grafting. Cuff technique-based interposition mouse model including new anticoagulation regime was conducted. Early vein graft thrombi may serve as a niche for smooth muscle cell colonization. The focal character of early thrombi may form the basis for the asymmetry of intimal hyperplasia.

SUMMARY

Background Autologous saphenous veins are widely used in coronary artery bypass grafting; however, 10 years after surgery, 40% of grafts are completely occluded, and another 30% show reduced blood flow. Objective In the past, the central processes and signaling pathways responsible for this loss of patency have been identified. However, one central finding in the process of graft failure is so far not understood: the asymmetric character of intimal hyperplasia. It was the goal of the present study to address this aspect. Methods By the use of a cuff technique-based vein interposition mouse model with a new anticoagulation regime, alterations in vein grafts were analyzed 1 h, 1 day, 2 days, 3 days, 7 days and 21 days after reperfusion by means of immunolabeling, histochemistry, and high-resolution ultrasound. Results The novel and major finding of this study is that the vein graft thrombus may serve as a niche that is infiltrated and colonized by smooth muscle cells (SMCs). Fibroblast growth factor-1 and platelet-derived growth factor-B may be the SMC-attracting factors in the thrombus. The focal character of early thrombi may define the focal and asymmetric character of vein graft intimal hyperplasia. Conclusions Inhibiting the formation and reducing the size of early thrombi is an old concept for reducing vein graft failure. However, in light of the present new findings obtained under a clinic-like anticoagulation regime, early vein graft thrombus prevention/size reduction should be revisited in the prevention of graft failure.

Pathophysiology of native coronary, vein graft, and in-stent atherosclerosis

Plaque rupture, usually of a precursor lesion known as a 'vulnerable plaque' or 'thin-cap fibroatheroma', is the leading cause of thrombosis. Less-frequent aetiologies of coronary thrombosis are erosion, observed with greatest incidence in women aged <50 years, and eruptive calcified nodules, which are occasionally identified in older individuals. Various treatments for patients with coronary artery disease, such as CABG surgery and interventional therapies, have led to accelerated atherosclerosis. These processes occur within months to years, compared with the decades that it generally takes for native disease to develop. Morphological identifiers of accelerated atherosclerosis include macrophage-derived foam cells, intraplaque haemorrhage, and thin fibrous cap. Foam-cell infiltration can be observed within 1 year of a saphenous vein graft implantation, with subsequent necrotic core formation and rupture ensuing after 7 years in over one-third of patients. Neoatherosclerosis occurs early and with greater prevalence in drug-eluting stents than in bare-metal stents and, although rare, complications of late stent thrombosis from rupture are associated with high mortality. Comparison of lesion progression in native atherosclerotic disease, atherosclerosis in saphenous vein grafts, and in-stent neoatherosclerosis provides insight into the pathogenesis of atheroma formation in natural and iatrogenic settings.

Percutaneous coronary intervention in patients with previous coronary artery bypass grafting (from the j-Cypher Registry)

A paucity of data is available from large-scale studies evaluating the long-term outcomes of percutaneous coronary intervention in patients who had previously undergone coronary artery bypass grafting (CABG) in the drug-eluting stent era. Of 12,812 patients who had undergone sirolimus-eluting stent implantation in the j-Cypher registry, 919 (7.2%) had a history of CABG and had significantly higher crude 5-year mortality (19.9% vs 14.0%, p <0.001). After adjusting for confounders, the excess risk of death was no longer significant (hazard ratio 0.99, 95% confidence interval 0.83 to 1.18, p = 0.90), and the adjusted risk of target lesion revascularization was significantly higher in patients with previous CABG than in those without (hazard ratio 1.25, 95% confidence interval 1.06 to 1.47, p = 0.01). Of the patients with previous CABG, those who had undergone ≥1 saphenous vein graft intervention had significantly higher adjusted risks of cardiac death (hazard ratio 2.21, 95% confidence interval 1.26 to 3.76, p = 0.01), myocardial infarction (hazard ratio 2.56, 95% confidence interval 1.10 to 5.60, p = 0.03), target lesion revascularization (hazard ratio 2.65, 95% confidence interval 1.82 to 3.81, p <0.001), and definite stent thrombosis (hazard ratio 7.70, 95% confidence interval 1.99 to 29.1, p = 0.004) compared with those who underwent percutaneous coronary intervention only for the native coronary artery. In conclusion, the adjusted mortality was similar between patients with and without previous CABG, despite a significantly different risk of target lesion revascularization. Among the patients with previous CABG, those with saphenous vein graft intervention using a first-generation drug-eluting stent had worse clinical outcomes than those with a native coronary artery target only.

Why is the mammary artery so special and what protects it from atherosclerosis?

The internal mammary artery (IMA) grafts have been associated with long-term patency and improved survival as compared to saphenous vein grafts (SVGs). Early failure of IMA is attributed to poor surgical technique and less with thrombosis. Similarly, bypass surgery especially with the use of IMA has also been shown to be superior at 1-year as well as over five years compared to percutaneous procedures, including the use of drug-eluting stents for the treatment of coronary artery disease. The superiority of IMAs over SVGs can be attributed to its striking resistance to the development of atherosclerosis. Structurally its endothelial layer shows fewer fenestrations, lower intercellular junction permeability, greater anti-thrombotic molecules such as heparin sulfate and tissue plasminogen activator, and higher endothelial nitric oxide production, which are some of the unique ways that make the IMA impervious to the transfer of lipoproteins, which are responsible for the development of atherosclerosis. A better comprehension of the molecular resistance to the generation of adhesion molecules that are involved in the transfer of inflammatory cells into the arterial wall that also induce smooth muscle cell proliferation is needed. This basic understanding is crucial to championing the use of IMA as the first line of defense for the treatment of coronary artery disease.

Two-year follow-up of outcomes of second-generation everolimus-eluting stents versus first-generation drug-eluting stents for stenosis of saphenous vein grafts used as aortocoronary conduits

Second-generation everolimus-eluting stents (EESs) have demonstrated superiority in efficacy and safety compared with first-generation drug-eluting stents (DESs) in the treatment of native coronary artery lesions. The present study evaluated and compared the safety and efficacy of EESs and first-generation DESs in saphenous vein graft lesions. The EES group consisted of 88 patients with 96 lesions, and the first-generation DES group consisted of 243 patients with 317 lesions (sirolimus-eluting stents, n = 212; paclitaxel-eluting stents, n = 105). The end points included target lesion revascularization, target vessel revascularization, major adverse cardiovascular events (composite of all-cause death, myocardial infarction, and target vessel revascularization), and definite stent thrombosis at 2 years. The groups had similar baseline characteristics and graft ages (128.1 ± 77.5 vs 132.4 ± 90.8 months, p = 0.686). The EES group had more type C lesions and less embolic protection device use. The peak postprocedure values of creatinine kinase-MB and troponin I were similar between the 2 groups. Overall, major adverse cardiovascular events occurred in 18.2% of EES patients and 35.0% of first-generation DES patients (p = 0.003), mainly driven by a lower target vessel revascularization rate (6.8% vs 24.5%, p <0.001). The target lesion revascularization rate was lower in the EES group (1.1% vs 11.6%, p = 0.005). Stent thrombosis was low and similar between the 2 groups (0% vs 0.8%, p = 1.000). On multivariate analysis, the type of DES implanted and graft age were the only independent predictors of major adverse cardiovascular events. In conclusion, the superiority of EESs compared with first-generation DESs shown in native artery lesions has been extended to saphenous vein graft lesions and should be considered as the DES of choice for this lesion type.

Comparison of outcomes of patients with ST-segment elevation myocardial infarction with versus without previous coronary artery bypass grafting (from the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction [HORIZONS-AMI] trial)

The present substudy from the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial assessed the outcomes and their relation to different antithrombotic regimens in patients with previous coronary artery bypass grafting (CABG) treated with primary percutaneous coronary intervention. Of 3,599 patients with information regarding a history of CABG, 105 (2.9%) had previously undergone CABG. Of these 105 patients, 46 were randomized to heparin plus a glycoprotein IIb/IIIa inhibitor and 59 to bivalirudin. The patients with versus without previous CABG were less frequently triaged to primary percutaneous coronary intervention (83.8% vs 93.2%, p = 0.0002) and had a longer door-to-balloon time (median 1.9 vs 1.6 hours, p = 0.047), lower rates of final Thrombolysis In Myocardial Infarction flow grade 2 to 3 in the intervened vessel (92.6% vs 97.8%, p = 0.007), and less frequent rates of complete or partial ST-segment resolution (66.3% vs 77.6%, p = 0.019). At 3 years, previous CABG was associated with a significantly greater incidence of major adverse cardiovascular events (36.4% vs 21.4%, p <0.001) owing to greater rates of mortality (11.2% vs 6.7%, p = 0.08), reinfarction (11.6% vs 7.1%, p = 0.09), stroke (5.1% vs 1.8%, p = 0.013), and ischemic target vessel revascularization (23.6% vs 12.9%, p = 0.005). The outcomes did not differ significantly as a function of the antithrombotic regimen. On multivariate analysis, previous CABG was an independent predictor of 3-year ischemic stroke (hazard ratio 3.57, 95% confidence interval 1.09 to 11.66). Intervention on the saphenous vein graft versus the native vessel predicted 3-year major adverse cardiovascular events (hazard ratio 2.69, 95% confidence interval 1.17 to 6.19). In the HORIZONS-AMI trial, previous CABG was associated with a delay to mechanical reperfusion and lower rates of percutaneous coronary intervention and patency of the infarct related vessel along with worse clinical outcomes.

Pathology of Saphenous Vein Grafts

Saphenous vein grafts (SVGs) are the most used conduits in coronary artery bypass graft (CABG) surgery; however, they are susceptible to accelerated atherosclerosis. Clinical studies have shown 10-year patency rates of SVG can be as low as 50% to 60%. This article highlights changes that are observed following CABG surgery using SVG, including intimal thickening to the development of atherosclerotic changes, and how these changes in vein graft are different from those observed in native atherosclerosis. It also discusses the role of risk factors that contribute to acceleration of SVG atherosclerosis.