Aortocoronary saphenous vein graft disease: pathogenesis, predisposition, and prevention

Atorvastatin Reduces In Vivo Fibrin Deposition and Macrophage Accumulation, and Improves Primary Patency Duration and Maturation of Murine Arteriovenous Fistula

BACKGROUND

Arteriovenous fistulas placed surgically for dialysis vascular access have a high primary failure rate resulting from excessive inward remodeling, medial fibrosis, and thrombosis. No clinically established pharmacologic or perisurgical therapies currently address this unmet need. Statins' induction of multiple anti-inflammatory and antithrombotic effects suggests that these drugs might reduce arteriovenous fistula failure. Yet, the in vivo physiologic and molecular effects of statins on fistula patency and maturation remain poorly understood.

METHODS

We randomized 108 C57Bl/6J mice to receive daily atorvastatin 1.14 mg/kg or PBS (control) starting 7 days before end-to-side carotid artery-jugular vein fistula creation and for up to 42 days after fistula creation. We then assessed longitudinally the effects of statin therapy on primary murine fistula patency and maturation. We concomitantly analyzed the in vivo arteriovenous fistula thrombogenic and inflammatory macrophage response to statin therapy, using the fibrin-targeted, near-infrared fluorescence molecular imaging agent FTP11-CyAm7 and dextranated, macrophage-avid nanoparticles CLIO-VT680.

RESULTS

In vivo molecular-structural imaging demonstrated that atorvastatin significantly reduced fibrin deposition at day 7 and macrophage accumulation at days 7 and 14, findings supported by histopathologic and gene-expression analyses. Structurally, atorvastatin promoted favorable venous limb outward remodeling, preserved arteriovenous fistula blood flow, and prolonged primary arteriovenous fistula patency through day 42 (P<0.05 versus control for all measures).

CONCLUSIONS

These findings provide new in vivo evidence that statins improve experimental arteriovenous fistula patency and maturation, indicating that additional clinical evaluation of statin therapy in patients on dialysis undergoing arteriovenous fistula placement is warranted.

A randomized, double-blind, placebo-controlled trial investigating the effect of ticagrelor on saphenous vein graft patency in patients undergoing coronary artery bypass grafting surgery-Rationale and design of the POPular CABG trial

RATIONALE

An estimated 15% of saphenous vein grafts (SVGs) occlude in the first year after coronary artery bypass grafting (CABG) despite aspirin therapy. Graft occlusion can result in symptoms, myocardial infarction, and death. SVG occlusion is primarily caused by atherothrombosis, in which platelet activation plays a pivotal role. Evidence regarding the effect of stronger platelet inhibition on SVG patency after CABG is limited. The main objective of the POPular CABG trial is to determine whether dual antiplatelet therapy with aspirin plus ticagrelor improves SVG patency when compared to aspirin alone.

STUDY

The POPular CABG is a randomized, double-blind, placebo-controlled, multicenter trial investigating the effect of adding ticagrelor to standard aspirin therapy on the rate of SVG occlusion. A total of 500 patients undergoing CABG with ≥ 1 SVG are randomized to ticagrelor or placebo. The primary end point is SVG occlusion rate, assessed with coronary computed tomography angiography at 1 year. Secondary end points are stenoses and occlusions in both SVGs and arterial grafts and SVG failure at 1 year, defined as a composite of SVG occlusion on coronary computed tomography angiography or coronary angiography, SVG revascularization, myocardial infarction in the territory supplied by an SVG, or sudden death. Safety end points are bleeding events at 30 days and 1 year.

CONCLUSION

The POPular CABG trial investigates whether adding ticagrelor to standard aspirin after CABG reduces the rate of SVG occlusion at 1 year.

The placental growth factor attenuates intimal hyperplasia in vein grafts by improving endothelial dysfunction

Saphenous vein grafts (SVG) patency is limited by intimal hyperplasia (IH) caused by endothelial dysfunction. This study aimed to explore the effect of placental growth factor (PlGF) on the endothelial function of SVG. In rat models of external jugular vein-carotid artery graft treated with PlGF or saline hydrogel, PlGF inhibited vein graft IH (day 28: 12.0 ± 1.9 vs. 61.7 ± 13.1 μm, P < 0.001), promoted microvessel proliferation (day 14: 33.3% 3+ vs. 50.0% 2+, P = 0.03), and increased nitric oxide (NO) production (P < 0.05 on days 1/3/5) and NO synthase (NOS) expression by immunohistochemistry. In human umbilical vein endothelial cells (HUVECs) cultured under hypoxia and treated or not with PlGF, PlGF restored the survival (50 ng/ml PlGF, 48 h: 91.7 ± 0.6% vs. 84.9 ± 0.5%, P < 0.01), migration (by Matrigel assay), and tube formation ability (junctions, tubules, and tubule total length; all P < 0.01) of HUVECs after hypoxia. PlGF increased NO production through increased eNOS expression (P < 0.05), without changes in iNOS expression. The mRNA expression of eNOS decreased after the addition of the PI3K inhibitor LY294002 (P < 0.05). PlGF promoted the protein expression of eNOS by up-regulating AKT, and the AKT and eNOS protein levels were decreased after adding LY294002 (all P < 0.05). In conclusion, PlGF is a candidate for the inhibition of IH in SVG after coronary artery bypass graft. The effects of PlGF are mediated by the upregulation of the eNOS mRNA and protein through the PI3K/AKT signaling pathway. PlGF promotes the secretion of NO by endothelial cells and thereby reduces the occurrence and development of IH.

Early Stage of Atherosclerosis in Aortocoronary Saphenous Vein Grafts: Intravascular Ultrasound Study

Introduction

Angiographically visible plaques in patent vein grafts are usually detected years after surgery. Our aim was to examine early plaque formation in vein grafts.

Methods

Bypass angiography and intravascular ultrasonography (IVUS) examination were performed on 77 aortocoronary saphenous vein grafts (SVGs) implanted in 36 patients during the first 2 years after CABG. In each graft, a good quality 25 mm ultrasound image was analyzed. We measured: plaque area, lumen area, external elastic membrane (EEM) area, graft area and wall area. For the comparative assessment of SVGs, the index plaque area/EEM area was calculated. Data were analyzed for the following 4 time periods: I – 0-4 months (22 grafts), II – 5-8 months (23 grafts), III – 9-12 months (19 grafts) and IV – 13-16 months (13 grafts) after CABG. Student’s t and Fisher-Snedecor tests were used for the purpose of statistical analysis in this retrospective study.

Results

In period I, plaque formation (neointimal) was observed in 10 grafts (45%), with a mean plaque area of 1.59 mm., in 6 grafts (26%) in period II, with a mean plaque area of 1.03 mm. and in 15 grafts (71%) in period III, with a mean plaque area of 1.41 mm., and in all (100%) grafts in period IV, with mean plaque area of 2,3 mm.. Average index plaque area/EEM area in periods I, II, III and IV were 0.12, 0.08, 0.13 and 0.22. We have showed a significant plaque increase between periods II and IV(P=0.038).

Conclusion

IVUS showed plaque in about 40% of venous grafts during the first year after CABG. Between 13-16 months plaque was visible in all studied grafts.

No improvements in long-term outcome after coronary artery bypass grafting with arterial grafts as a second conduit: a Swedish nationwide registry study

OBJECTIVES

Coronary artery bypass grafting using saphenous vein grafts (SVGs) in addition to the left internal mammary artery (IMA) graft is vitiated by poor long-term patency of the vein grafts. Hypothetically, the increased use of arterial grafts could confer even better outcomes. Our goal was to evaluate results after coronary artery bypass grafting in Sweden, where arterial grafts were used as a second conduit.

METHODS

Within the Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) registry, we identified patients who had coronary artery bypass grafting from 2001 to 2015 using the IMA and the SVG, the radial artery (RA) or the additional IMA [bilateral IMA (BIMA)] as a second conduit. Deaths, postoperative incidence of coronary angiography and need for reintervention were recorded, and multivariable adjusted hazard ratios were calculated for different types of grafts.

RESULTS

The study population comprised 46 343 cases of IMA + SVG, 1036 cases of IMA + RA and 862 cases of BIMA. The mean follow-up time (SD) was 9.3 (4.2) years for IMA + SVG, 10.7 (4.1) years for IMA + RA grafts and 5.5 (5.0) years for the BIMA graft. The adjusted hazard ratio for death was (95% confidence interval) 1.01 (0.89-1.14) for IMA + RA and 0.87 (0.72-1.06) for BIMA grafts compared with IMA + SVG. The adjusted hazard ratio for the first angiographic examination was (95% confidence interval) 0.96 (0.84-1.10) for IMA + RA and 1.13 (0.95-1.35) for BIMA grafts. The adjusted hazard ratio for the need for reintervention was (95% confidence interval) 0.91 (0.75-1.09) for IMA + RA and 1.26 (1.00-1.58) for BIMA grafts.

CONCLUSIONS

Patients who had arterial grafts as second conduits did not demonstrate a better outcome in any of the studied end-points. Radial artery grafts seem to be preferable to BIMA grafts as an alternative to an SVG.

Differences in Expression of Genes Involved in Bone Development and Morphogenesis in the Walls of Internal Thoracic Artery and Saphenous Vein Conduits May Provide Markers Useful for Evaluation Graft Patency

Coronary artery bypass grafting (CABG) is one of the most efficient procedures for patients with advanced coronary artery disease. From all the blood vessels with the potential to be used in this procedure, the internal thoracic artery (ITA) and the saphenous vein (SV) are the most commonly applied as aortocoronary conduits. Nevertheless, in order to evaluate the graft patency and efficiency effectively, basic knowledge should be constantly expanding at the molecular level as well, as the understanding of predictive factors is still limited. In this study, we have employed the expressive microarray approach, validated with Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR), to analyze the transcriptome of both venous and arterial grafts. Searching for potential molecular factors, we analyzed differentially expressed gene ontologies involved in bone development and morphogenesis, for the possibility of discovery of new markers for the evaluation of ITA and SV segment quality. Among three ontological groups of interest—“endochondral bone morphogenesis”, “ossification”, and “skeletal system development”—we found six genes common to all of them. BMP6, SHOX2, COL13A1, CSGALNACT1, RUNX2, and STC1 showed differential expression patterns in both analyzed vessels. STC1 and COL13A1 were upregulated in ITA samples, whereas others were upregulated in SV. With regard to the Runx2 protein function in osteogenic phenotype regulation, the RUNX2 gene seems to be of paramount importance in assessing the potential of ITA, SV, and other vessels used in the CABG procedure. Overall, the presented study provided valuable insight into the molecular background of conduit characterization, and thus indicated genes that may be the target of subsequent studies, also at the protein level. Moreover, it has been suggested that RUNX2 may be recognized as a molecular marker of osteogenic changes in human blood vessels.

Why Use the Radial Artery? The Saphenous Vein is the Second Graft of Choice for CABG in Brazil

The saphenous vein (SV) is the most commonly used conduit for coronary artery bypass surgery (CABG) and the second conduit of choice in Brazil and many other countries. The radial artery (RA) is suggested, by some, to be superior to SV grafts, although its use in the USA declined over a 10 year period. The patency of SV grafts (SVG) is improved when the vein is harvested with minimal trauma using the no-touch (NT) technique. This improved performance is due to the preservation of the outer pedicle surrounding the SV and reduction in vascular damage that occurs when using conventional techniques (CT) of harvesting. While the patency of NT SVGs has been shown superior to the RA at 36 months in one study, data from the RADIAL trial suggests the RA to be the superior conduit. When additional data using NT SVG is included in this trial the difference in risk of graft occlusion between the RA and SV grafts dissipates with there no longer being a significant difference in patency between conduits. The importance of preserving SV structure and the impact of NT harvesting on conduit choice for CABG patients are discussed in this short review.

A mathematical model to evaluate hemodynamic effects of the graft anastomosis in coronary surgery

The durability and patency of a coronary graft can be negatively affected by technical factors that induce thrombosis of the graft and poor prognosis of patients undergoing coronary artery bypass grafting. Technical factors include the inclination angle of the coronary anastomosis and the alignment between the main vessel and the inserted vessel as graft. We have studied a mathematical model aimed to assess the best angulation of the anastomosis and the influence of a correct alignment in order to prevent the risk of early graft occlusion. From data obtained from the mathematical model, in our opinion an inclination of the anastomotic angle of at least 30° seems to be a right choice when performing a coronary artery bypass graft. In addition, the incision of the coronary vessel should be done perfectly on the same axis as that performed on the graft, since even a deviation of the axis of the anastomosis of only 10° can create turbulence of the flow in the anastomosis site, which is accentuated when the deviation reaches 20°.

Does Early Graft Patency Benefit from Perioperative Statin Therapy? A Propensity Score-Matched Study of Patients Undergoing Off-Pump Coronary Artery Bypass Surgery

BACKGROUND

Decreased graft patency after off-pump coronary artery bypass grafting (OPCAB) leads to substantial increases in cardiac events. However, there is paucity of data on efficacy and safety of perioperative statin therapy for OPCAB populations.

METHODS

582 patients undergoing OPCAB in a single-institution database (October 1, 2009-September 30, 2012) were stratified by perioperative continuation of statin therapy (CS group, n=398) or not (DS group, n=184). Inverse probability weighted propensity adjustment was used to account for treatment assignment bias, resulting in a well-matched cohort. Primary outcomes were graft patency at an average of five days after operation and in-hospital mortality. Secondary outcomes included intraoperative blood loss, liver, and renal functions.

RESULTS

No in-hospital death occurred in this study. Early graft patency rates after OPCAB were 98.4% (1255 of 1275 grafts) in the CS group and 98.0% (583 of 595 grafts, P=0.486) in the DS group. Secondary outcomes showed a reduction in blood loss during operation (438.53 mL versus 480.47 mL, P=0.01). Continuation of statin therapy is associated with alanine transaminase (ALT) elevation (49.67 U/L versus 34.52 U/L, P<0.001), as well as aspartate transaminase (33.54 U/L versus 28.10 U/L, P<0.001). Abnormal ALT elevation was observed in 8.9% of the CS group and 3.1% in DS (odds ratio 3.06, 95% confidence interval, 1.77 to 5.29, P<0.001). There was no significant difference in estimated glomerular filtration rate (76.28 mL/min/1.73m2 versus 76.13 mL/min/1.73m2, P=0.90). Subgroup analyses suggested that graft occlusion was less common in CS than in DS group among smoking patients (odds ratio 0.41, 95% confidence interval, 0.20 to 0.86, P=0.026).

CONCLUSIONS

Perioperative continuation of statin therapy did not improve early graft patency in OPCAB patients. A lower risk of graft occlusion was observed among smoking patients. Continuous statin use correlated with liver function elevation (Clinical Trials.gov number, NCT01268917).

Long-Term Outcomes in Coronary Artery Bypass Graft Patients Using Internal Thoracic Artery with Ipsilateral Arteriovenous Shunt for Hemodialysis

Background

The goal of this study was to evaluate the long-term results of coronary artery bypass grafting (CABG) using internal thoracic artery (ITA) grafts in hemodialysis (HD) patients with arteriovenous (AV) fistulae or AV grafts involving the ipsilateral or contralateral brachial artery or radial artery.

Methods

From March 2007 to May 2017, 76 end-stage renal disease (ESRD) patients with an upper limb AV fistula or graft for HD underwent CABG at a single center. Group A included 23 patients who underwent CABG using an ITA graft ipsilateral to the AV vascular access (AVVA); Group B included 22 patients who underwent CABG using a contralateral ITA with AVVA; and Group C included 29 patients who underwent CABG with AVVA without the use of an ITA graft. The primary end-point was death from any cause.

Results

The average follow-up period was 34.4 ± 26.9 months. Death from any cause occurred in 6 (26.09%) patients in Group A, 8 (36.36%) patients in Group B, and 17 (58.62%) patients in Group C (log-rank p = 0.04). There was no significant difference in death rate between Groups A and B. The risk of death was lower in the patients with CABG using an ITA graft (ITA CABG) compared to the patients without ITA CABG [HR 0.41 (95% CI, 0.20-0.84), p = 0.015].

Conclusions

The HD patients who underwent CABG with an ipsilateral location of the ITA and AVVA did not have an increased risk of death compared to the patients who underwent CABG with a contralateral location of the ITA and AVVA. In addition, the use of ITA in CABG resulted in better outcomes in the HD patients.

Inhibition of the Akt1-mTORC1 Axis Alters Venous Remodeling to Improve Arteriovenous Fistula Patency

Arteriovenous fistulae (AVF) are the most common access created for hemodialysis, but up to 60% do not sustain dialysis within a year, suggesting a need to improve AVF maturation and patency. In a mouse AVF model, Akt1 regulates fistula wall thickness and diameter. We hypothesized that inhibition of the Akt1-mTORC1 axis alters venous remodeling to improve AVF patency. Daily intraperitoneal injections of rapamycin reduced AVF wall thickness with no change in diameter. Rapamycin decreased smooth muscle cell (SMC) and macrophage proliferation; rapamycin also reduced both M1 and M2 type macrophages. AVF in mice treated with rapamycin had reduced Akt1 and mTORC1 but not mTORC2 phosphorylation. Depletion of macrophages with clodronate-containing liposomes was also associated with reduced AVF wall thickness and both M1- and M2-type macrophages; however, AVF patency was reduced. Rapamycin was associated with improved long-term patency, enhanced early AVF remodeling and sustained reduction of SMC proliferation. These results suggest that rapamycin improves AVF patency by reducing early inflammation and wall thickening while attenuating the Akt1-mTORC1 signaling pathway in SMC and macrophages. Macrophages are associated with AVF wall thickening and M2-type macrophages may play a mechanistic role in AVF maturation. Rapamycin is a potential translational strategy to improve AVF patency.

Role of smooth muscle cells in coronary artery bypass grafting failure

Atherosclerosis is the underlying pathology of many cardiovascular diseases. The formation and rupture of atherosclerotic plaques in the coronary arteries results in angina and myocardial infarction. Venous coronary artery bypass grafts are designed to reduce the consequences of atherosclerosis in the coronary arteries by diverting blood flow around the atherosclerotic plaques. However, vein grafts suffer a high failure rate due to intimal thickening that occurs as a result of vascular cell injury and activation and can act as 'a soil' for subsequent atherosclerotic plaque formation. A clinically-proven method for the reduction of vein graft intimal thickening and subsequent major adverse clinical events is currently not available. Consequently, a greater understanding of the underlying mechanisms of intimal thickening may be beneficial for the design of future therapies for vein graft failure. Vein grafting induces inflammation and endothelial cell damage and dysfunction, that promotes vascular smooth muscle cell (VSMC) migration, and proliferation. Injury to the wall of the vein as a result of grafting leads to the production of chemoattractants, remodelling of the extracellular matrix and cell-cell contacts; which all contribute to the induction of VSMC migration and proliferation. This review focuses on the role of altered behaviour of VSMCs in the vein graft and some of the factors which critically lead to intimal thickening that pre-disposes the vein graft to further atherosclerosis and re-occurrence of symptoms in the patient.

Biomechanics and Mechanobiology of Saphenous Vein Grafts

Within several weeks of use as coronary artery bypass grafts (CABG), saphenous veins (SV) exhibit significant intimal hyperplasia (IH). IH predisposes vessels to thrombosis and atherosclerosis, the two major modes of vein graft failure. The fact that SV do not develop significant IH in their native venous environment coupled with the rapidity with which they develop IH following grafting into the arterial circulation suggests that factors associated with the isolation and preparation of SV and/or differences between the venous and arterial environments contribute to disease progression. There is strong evidence suggesting that mechanical trauma associated with traditional techniques of SV preparation can significantly damage the vessel and might potentially reduce graft patency though modern surgical techniques reduces these injuries. In contrast, it seems possible that modern surgical technique, specifically endoscopic vein harvest, might introduce other mechanical trauma that could subtly injure the vein and perhaps contribute to the reduced patency observed in veins harvested using endoscopic techniques. Aspects of the arterial mechanical environment influence remodeling of SV grafted into the arterial circulation. Increased pressure likely leads to thickening of the medial wall but its role in IH is less clear. Changes in fluid flow, including increased average wall shear stress, may reduce IH while disturbed flow likely increase IH. Nonmechanical stimuli, such as exposure to arterial levels of oxygen, may also have a significant but not widely recognized role in IH. Several potentially promising approaches to alter the mechanical environment to improve graft patency are including extravascular supports or altered graft geometries are covered.

Implications of coronary artery bypass grafting and percutaneous coronary intervention on disease progression and the resulting changes to the physiology and pathology of the native coronary arteries

Myocardial revascularization can be achieved through 2 different methods: coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI). Clinical trials comparing PCI and CABG generally use the composite end points of death, stroke, myocardial infarction and target vessel revascularization to determine superiority. Other effects of these interventions, including the preservation of normal coronary physiology, the response of the coronary tree to stressors and the response of the vessel wall to the revascularization intervention, are not routinely considered, but these may have significant implications for patients in the medium and long term. For PCI, relatively small differences in clinical outcomes have been reported between bare metal and drug-eluting stents, and the latter seems to have inconsistent and somewhat unpredictable effects on the vascular biology of the coronary arteries. In coronary bypass, the use of arterial conduits is associated with superior clinical outcomes, better long-term patency and the preservation of essentially normal coronary function after intervention. This review assembles the clinical, physiological, angiographic and pathological literature currently available and attempts to provide a more complete picture of the effects of CABG and PCI on coronary arteries.

Platelet to Lymphocyte Ratio in Cardiovascular Diseases: A Systematic Review

The platelet to lymphocyte ratio (PLR) is an integrated reflection of 2 opposite thrombotic/inflammatory pathways that are easily calculated from a complete blood count. The PLR initially served as a systemic inflammatory biomarker to predict the prognosis of neoplastic diseases. In recent years, the PLR has been used as a prognostic marker in cardiovascular (CV) conditions. In this review, we consider the evidence regarding the association of the PLR with CV disease (CVD) and its possible use as a prognostic marker of CVD. The role of PLR has been investigated in CV conditions in several studies. We assessed clinical trials using PubMed, EMBASE, and Web of Science (up to April 18, 2018) to evaluate the association between PLR and mortality/major adverse cardiac events in these conditions. Most of these studies reported significant relationships between a high PLR and diverse outcomes. In conclusion, we suggest that PLR is a cheap and easily available systemic inflammatory marker that can predict distinct outcomes in different types of CVD.

VENOUS CONDUITS IN CORONARY SURGERY: OLD PROBLEMS — NEW SOLUTIONS

The introduction of autovenous coronary artery bypass grafting (CABG) marked the era of surgical revascularization in patients with coronary artery disease. It provided effective treatment for angina and significantly improved the long-term prognosis. Venous transplants today remain the most popular conduits in coronary surgery due to their availability, ease of harvesting, and the absence of length restrictions. Despite the advantages of autovenous CABG, the main disadvantage is the high incidence of venous graft failure, which represents an important and unresolved problem in cardiac and cardiovascular surgery. On the other hand, the traditional allocation of a large saphenous vein implies the dissection of soft tissues throughout the length of the isolated conduit. Traumatic dissection causes a long-lasting persistent pain syndrome after surgery, frequent abnormalities in  skin sensitivity, and a high incidence of wound complications in the lower extremities. These complications lengthen the period of rehabilitation of patients and worsen the quality of life. There is an approach of isolating the vein in a block with surrounding tissues to optimize the long-term functioning of the venous shunt, however, this technique is even more traumatic than the traditional method, and therefore its use is limited in practice. On the other hand, the introduction of minimally invasive methods of isolation allowed to reduce the incidence of wound complications and to improve the cosmetic result, but there is no convincing data regarding the effect on the consistency of shunts in the long-term postoperative period. The problems associated with the use of venous conduits in CABG are multifaceted, and their solutions are necessary to improve the effectiveness of surgical revascularization.

Dual platelet antiaggregation therapy after myocardial revascularization surgery

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.

New-generation drug eluting stent vs. bare metal stent in saphenous vein graft - 1 year outcomes by a propensity score ascertainment (SVG Baltic Registry)

BACKGROUND

Data regarding the efficacy of the percutaneous coronary intervention (PCI) with new-designed drug-eluting stent (new-DES) vs. bare metal stent (BMS) of saphenous vein grafts (SVG) stenosis is scarce. The primary objective was to compare one-year clinical outcomes of PCI in stenosis of SVG using new-DES vs. BMS in a real-world population.

METHODS AND RESULTS

We carried out a multi-center registry comparing new-DES with BMS in all consecutive patients undergoing PCI of SVG. The primary composite endpoint was major adverse cardiac and cerebrovascular events (MACCE) at 1 year. This observation included 792 consecutive patients (mean age 69 ± 8.9y), treated with either new-DES (n = 379, 47.9%) or BMS (n = 413, 52.1%). Among patients treated with new-DES compared with BMS, there was a lower risk of MACCE (21.4% vs. 28.3%, HR = 0.69, 95% CI 0.50-0.95, p = 0.025) as well as myocardial infarction (MI) (6.3% vs. 12.1%; HR 0.49, 95% CI 0.30-0.82, p = 0.005) at 1 year. After propensity score adjustment, the similar, significant reduction in MACCE and MI was observed in favor of new-DES (HR 0.66, 95% CI 0.46-0.96, p = 0.030; and HR 0.53, 95% CI 0.31-0.92, p = 0.020, respectively).

CONCLUSION

In patients undergoing PCI of SVG, the use of new-DES is associated with a reduced 1-year rate of MACCE and MI compared to BMS.

State-of-the-Art Coronary Artery Bypass Grafting: Patient Selection, Graft Selection, and Optimizing Outcomes

Despite the progressive expansion of clinical indications for percutaneous coronary intervention and the increasingly high risk profile of referred patients, coronary artery bypass grafting (CABG) remains the mainstay in multivessel disease, providing good long-term outcomes with low complication rates. Multiple arterial grafting, especially if associated with anaortic techniques, might provide the best longer-term outcomes. A surgical approach individualized to the patients' clinical and anatomic characteristics, and surgeon and team experience, are key to excellent outcomes. Current evidence regarding patient selection, indications, graft selection, and potential strategies to optimize outcomes in patients treated with CABG is summarized.

Uncertainty quantification of simulated biomechanical stimuli in coronary artery bypass grafts

Coronary artery bypass graft surgery (CABG) is performed on more than 400,000 patients annually in the U.S. However, saphenous vein grafts (SVGs) implanted during CABG exhibit poor patency compared to arterial grafts, with failure rates up to 40% within 10 years after surgery. Differences in mechanical stimuli are known to play a role in driving maladaptation and have been correlated with endothelial damage and thrombus formation. As these quantities are difficult to measure in vivo, multi-scale coronary models offer a way to quantify them, while accounting for complex coronary physiology. However, prior studies have primarily focused on deterministic evaluations, without reporting variability in the model parameters due to uncertainty. This study aims to assess confidence in multi-scale predictions of wall shear stress and wall strain while accounting for uncertainty in peripheral hemodynamics and material properties. Boundary condition distributions are computed by assimilating uncertain clinical data, while spatial variations of vessel wall stiffness are obtained through approximation by a random field. We developed a stochastic submodeling approach to mitigate the computational burden of repeated multi-scale model evaluations to focus exclusively on the bypass grafts. This produces a two-level decomposition of quantities of interest into submodel contributions and full model/submodel discrepancies. We leverage these two levels in the context of forward uncertainty propagation using a previously proposed multi-resolution approach. The time- and space-averaged wall shear stress is well estimated with a coefficient of variation of <35%, but ignorance about the spatial distribution on the wall elastic modulus and thickness lead to large variations in an objective measure of wall strain, with coefficients of variation up to 100%. Sensitivity analysis reveals how the interactions between the flow and material parameters contribute to output variability.

Comparison of venous repair results using either arterial or vein grafts in a crush-avulsion injury model

Background/aim

Venous insufficiency after replantation or revascularization is one of the most common causes of limb loss in either the short or the long term. The aim of this study was to evaluate the results of a new technique to overcome venous insufficiency.

Materials and Methods

A crush-avulsion type of injury was formed in the femoral veins of rats of 3 separate groups. In the control group, primary repair was applied to the damaged veins and the remaining 2 groups were repaired with either an arterial graft or a vein graft. The success rates of anastomosis were then compared.

Results

In the control group the patency rate was 25% in the 2nd hour, 12.5% on the 2nd day, and 12.5% on the 10th day. The patency rate in the vein group was 87.5% in the 2nd hour, 50% on the 2nd day, and 37.5% on the 10th day, whereas the patency rates in the artery group were 100% in the 2nd hour, 87.5% on the 2nd day, and 75% on the 10th day.

Conclusion

Microsurgery requires experience and patience. It can be considered that the use of arterial grafts for venous repair in replantation after crush-avulsion type amputations can increase the success rate of replantation.

On-Pump Coronary Artery Bypass Graft: The State of the Art

BACKGROUND

Coronary artery bypass grafting (CABG) remains the standard of care for patients with coronary artery disease (CAD). Debate exists concerning several factors, which include percutaneous coronary intervention (PCI) vs. CABG, single vs. bilateral mammary artery grafts, radial artery vs. saphenous vein grafts, right internal mammary artery vs. radial artery grafts, endoscopic vs. open vein-graft harvesting, and on-pump vs. off- pump surgery. Moreover, challenging is the management of diabetic patients with CAD undergoing CABG. This review reports current indications, practice patterns, and outcomes of CABG.

METHODS

Randomized controlled trials comparing CABG to other therapeutical strategies for CAD were searched through MEDLINE, EMBASE, Cochrane databases, and proceedings of international meetings.

RESULTS

Large multicenter randomized and observational studies (SYNTAX, BEST, PRECOMBAT, ASCERT) have reported excellent outcomes in CABG patients, with always fewer rates of operative mortality and major morbidity, than PCI. The 10-year follow-up of ARTS II trial showed no difference between single and bilateral mammary artery. BARI 2D, MASS II, CARDia, FREEDOM trials showed that CABG is the best choice for diabetic patients.

CONCLUSION

CABG still represents one of the most widespread major surgeries, with well-known benefits on symptoms and prognosis in patients with CAD. However, further studies and follow-up data are needed to validate these evidences.

Drug-Eluting Versus Bare Metal Stents in Saphenous Vein Graft Intervention: An Updated Comprehensive Meta-Analysis of Randomized Trials

BACKGROUND

Drug eluting stents (DES) are preferred over bare metal stents (BMS) for native coronary artery revascularization unless contraindicated. However, the preferred stent choice for saphenous venous graft (SVG) percutaneous coronary interventions (PCI) is unclear due to conflicting results.

METHODS

PubMed, Clinical trials registry and the Cochrane Center Register of Controlled Trials were searched through June 2018. Seven studies (n = 1639) comparing DES versus BMS in SVG-PCI were included. Endpoints were major adverse cardiac events (MACE), cardiovascular mortality, all-cause mortality, myocardial infarction (MI), target vessel revascularization (TVR), target lesion revascularization (TLR), in-stent thrombosis, binary in-stent restenosis, and late lumen loss (LLL).

RESULTS

Overall, during a mean follow up of 32.1 months, there was no significant difference in the risk of MACE, cardiovascular mortality, all-cause mortality, MI, stent thrombosis, TVR and TLR between DES and BMS. However, short-term follow up (mean 11 months) showed lower rate of MACE (OR 0.66 [0.51, 0.85]; p = 0.002), TVR (OR 0.47 [0.23, 0.97]; p = 0.04) and binary in-stent restenosis (OR 0.14 [0.06, 0.37]; p < 0.0001) in DES as compared with BMS. This benefit was lost on long-term follow up with a mean follow up 35.5 months.

CONCLUSION

In this meta-analysis of SVG-PCI, DES use was associated with similar MACE, cardiovascular mortality, all-cause mortality, MI, in-stent thrombosis, TVR and TLR compared with BMS during long-term follow up. There was high incidence of MACE noted in both DES and BMS suggesting a need for exploring novel strategies to treat SVG disease to improve clinical outcomes.

Bilateral internal thoracic artery grafting: in situ or composite?

Bilateral internal thoracic artery (BITA) grafting is considered a superior choice for coronary artery bypass grafting (CABG). While the 10-year outcomes of BITA grafting from the recent Arterial Revascularization Trial (ART) are still pending, numerous observational studies have demonstrated the advantages of BITA grafting. These include better long-term graft patency and freedom from arteriosclerosis, in addition to higher survival rate compared to CABG using only the left internal thoracic artery (ITA). The different BITA configurations are in situ and composite-the choice of optimal grafting configuration is challenging. Patient factors such as coronary anatomy, presence of a diseased ascending aorta and the potential need for a future redo sternotomy will influence the choice of the grafting strategy. In situ BITA grafting is associated with excellent clinical outcomes and has been extensively described in the literature. However, uncertainties remain regarding the ideal in situ configuration and design. Composite BITA grafting is the other option that maximizes right ITA (RITA) utilization. In this configuration, the RITA is able to reach the distal circumflex and right coronary artery branches. This approach decreases the need for a third graft conduit.

Myocardial revascularization: the evolution of the STS database and quality measurement for improvement

The Society of Thoracic Surgeons (STS) is a not-for-profit organization dedicated to helping clinicians and researchers provide optimal outcomes for patients undergoing heart, lung, and esophageal surgery. The organization was founded in 1964 and has grown to now include over 7300 members in over 90 countries. The STS created a national database that collects detailed clinical information on patients undergoing adult cardiac, pediatric and congenital cardiac, and general thoracic operations. The data collected are used to produce risk-adjusted, nationally benchmarked performance assessments and feedback; facilitate voluntary public reporting; support quality initiatives; develop evidence-based guidelines; monitor long-term clinical outcomes; track device performance; and promote high-quality research collaboratives.

Current role of saphenous vein graft in coronary artery bypass grafting

Saphenous vein was the conduit used in the first series of coronary artery bypass grafting (CABG), and, with the exception of surgical revascularization of the left anterior descending artery, it remains the most commonly used bypass conduit. However, its durability and longevity are not ideal. Arterial grafts have better patency than saphenous vein grafts and therefore should be preferred over them. However, in certain situations, like grafting right coronary arteries with lesser degree of proximal stenosis and higher competitive flow, or in certain patient populations, like those at very high risk of wound infections and octogenarians, arterial grafting may not be the best option and saphenous vein grafting should be considered instead.

Long-term clinical outcomes after coronary artery bypass grafting with pedicled saphenous vein grafts

BACKGROUND

Coronary artery bypass grafting (CABG) using saphenous vein grafts (SVG) is vitiated by poor long-term patency of the vein grafts. Pedicled SVG harvested with the "no-touch" (NT) technique have demonstrated improved patency and could confer better outcomes. We aim to compare long-term results after CABG where NT or conventional technique was used for vein graft harvesting in a hypothesis-generating registry-based study.

METHODS

Two propensity score matched cohorts (1349 patients) undergoing CABG with veins harvested with NT (NTT) or conventional (CT) technique in Sweden over the period 2005-2015 were used to compare long-term outcomes. Mortality, postoperative incidence of coronary angiography and need for reintervention was recorded and multivariable hazard ratios adjusted for risk factors were calculated.

RESULTS

The mean follow-up time (SD) was 6.8 (3.3) years for NTT and 6.6 (3.2) years for CT. The adjusted hazard ratios for death, first angiography and need for reintervention for NTT patients were (95% CI) 0.97 (0.80-1.19), 0.76 (0.63-0.93), 0.91 (0.78-1.05), and 0.91 (0.71-1.17), respectively. Failed grafts were found in 43.2% of NTT patients and 53.6% of CT patients at angiography.

CONCLUSIONS

In this study NT grafting was associated with a lower risk for repeat angiography, however no difference could be observed for mortality and need for reintervention. The earlier reported improvements in patency of NT veins could possibly be reflected in an improved clinical outcome during the first 10 years after surgery.

Angiographic appearance of patent saphenous vein grafts more than 25 years after coronary artery bypass grafting

Nine patients with ten angiographical patent saphenous vein grafts (SVG) more than 25 years after coronary artery bypass grafting (CABG) at Kawasaki Medical School Hospital between 1976 and 1992 were reviewed. Patent SVG disease was assessed using the FitzGibbon classification, and clinical characteristics which might affect the longevity of SVG were retrospectively evaluated. The mean duration between surgery and current coronary angiography was approximately 30 years (25-35 years). There were two perfectly patent SVGs (FitzGibbon AI, 35 and 32 years after surgery), both of which were bypass grafts to the left anterior descending arteries (LAD). The other eight grafts exhibited some vein graft disease (BII:3, BIII:5). The sequential anastomosis was performed for 5 SVGs. The SVGs bypassed to the good run-off LAD, sequential bypass, strict medical management including cessation of smoking and body weight control may contribute to the slow progression of vein graft disease after CABG.

Long-term performance of an external stent for saphenous vein grafts: the VEST IV trial

Background

Externally stenting saphenous vein grafts reduces intimal hyperplasia, improves lumen uniformity and reduces oscillatory shear stress 1 year following surgery. The present study is the first to present the longer-term (4.5 years) performance and biomechanical effects of externally stented saphenous vein grafts.

Methods

Thirty patients previously implanted with the VEST external stent in the randomized, within-patient-controlled VEST I study were followed up for adverse events; 21 of these were available to undergo coronary angiography and intravascular ultrasound.

Results

Twenty-one stented and 29 nonstented saphenous vein grafts were evaluated by angiography and ultrasound at 4.5 ± 0.3 years. Vein graft failure rates were comparable between stented and nonstented grafts (30 and 23% respectively; p = 0.42). All failures were apparent at 1 year except for one additional nonstented failure at 4.5 years. In patent vein grafts, Fitzgibbon perfect patency remained significantly higher in the stented versus nonstented vein grafts (81 and 48% respectively, p = 0.002), while intimal hyperplasia area (4.27 mm² ± 1.27 mm² and 5.23 mm² ± 1.83 mm² respectively, p < 0.001) and thickness (0.36 mm ± 0.09 mm and 0.42 mm ± 0.11 mm respectively, p < 0.001) were significantly reduced. Intimal hyperplasia proliferation correlated with lumen uniformity and with the distance between the stent and the lumen (p = 0.04 and p < 0.001 respectively).

Conclusions

External stenting mitigates saphenous vein graft remodeling and significantly reduces diffuse intimal hyperplasia and the development of lumen irregularities 4.5 years after coronary artery bypass surgery. Close conformity of the stent to the vessel wall appears to be an important factor.

Trial registration

NCT01415245. Registered 11 August 2011.

Antiplatelet effects of ticagrelor versus clopidogrel after coronary artery bypass graft surgery: A single-center randomized controlled trial

OBJECTIVE

The study objective was to compare the onset of platelet inhibition (inhibition of platelet aggregation) between ticagrelor 90 mg twice per day and clopidogrel 75 mg once per day in patients receiving coronary artery bypass grafting.

METHODS

In a single-center, randomized, open-label study, 140 patients receiving coronary artery bypass grafting were randomly assigned to the aspirin + ticagrelor group or the aspirin + clopidogrel group in a 1:1 ratio. Participants in the aspirin + ticagrelor group took aspirin 100 mg once per day and ticagrelor 90 mg twice per day. Participants in the aspirin + clopidogrel group took aspirin 100 mg once per day and clopidogrel 75 mg once per day. Platelet function was determined before study treatment (0 hours); at 2 hours, 8 hours, 24 hours, and 72 hours after medication; and during follow-up at 30 days after surgery.

RESULTS

Inhibition of platelet aggregation at 2 hours after the first drug administration was greater for the aspirin + ticagrelor group than for the aspirin + clopidogrel group (34.2% [interquartile range, 9.1-66.0] vs 5.3% [interquartile range, -14.3-22.0], P < .001) and at all times in the study period (P < .001). More patients reached inhibition of platelet aggregation maximum within 24 hours in the aspirin + ticagrelor group than in the aspirin + clopidogrel group (52.9% vs 27.5%, P = .006). The average inhibition of platelet aggregation maximum from 2 to 24 hours was still greater in the aspirin + ticagrelor group than in the aspirin + clopidogrel group (72.3% ± 15.4% vs 49.2% ± 46.8%, P < .001). There were no differences in terms of bleeding or major adverse cardiac events between the 2 groups.

CONCLUSIONS

In patients receiving coronary artery bypass grafting, the onset of action was faster and the peak inhibition of platelet aggregation was higher with ticagrelor than with clopidogrel.

Antiplatelet drug selection in PCI to vein grafts in patients with acute coronary syndrome and adverse clinical outcomes: Insights from the British Cardiovascular Intervention Society database

OBJECTIVE

This study aims to evaluate outcomes associated with different P2Y12 agents in Saphenous Vein graft (SVG) percutaneous coronary intervention (PCI).

BACKGROUND

SVG PCI is associated with greater risks of ischemic complications, compared with native coronary PCI. Outcomes associated with the use of potent P2Y12 blocking drugs, Prasugrel and Ticagrelor, in SVG PCI are unknown.

METHODS

Patients included in the study underwent SVG PCI in the United Kingdom between 2007 and 2014 for acute coronary syndrome and were grouped by P2Y12 antiplatelet use. In-hospital major adverse cardiac events, major bleeding and 30-day and 1-year mortality were examined. Multiple imputations with chained equations to impute missing data were used. Adjustment for baseline imbalances was performed using (1) multiple logistic regression (MLR) and (separately) (2) propensity score matching (PSM).

RESULTS

Data weres analyzed from 8,119 patients and most cases were treated with Clopidogrel (n = 7,401), followed by Ticagrelor (n = 497) and Prasugrel (n = 221). In both MLR and PSM models, there was no significant evidence to suggest that either Prasugrel or Ticagrelor was associated with significantly lower 30-day mortality compared with Clopidogrel. The odds ratios reported from the multivariable analysis were 1.22 (95% CI: 0.60-2.51) for Prasugrel vs. Clopidogrel and 0.48 (95% CI: 0.20-1.16) for Ticagrelor vs. Clopidogrel. No significant differences were seen for in-hospital ischemic or bleeding events.

CONCLUSIONS

Our real world national study provides no clear evidence to indicate that use of potent P2Y12 blockers in SVG PCI is associated with improved clinical outcomes.

Endothelial repair is dependent on CD11c+ leukocytes to establish regrowing endothelial sheets with high cellular density

Endothelial injury makes the vessel wall vulnerable to cardiovascular diseases. Injured endothelium regenerates by collective sheet migration, that is, the endothelial cells coordinate their motion and regrow as a sheet of cells with retained cell-cell contacts into the wounded area. Leukocytes appear to be involved in endothelial repair in vivo; however, little is known about their identity and role in the reparative sheet migration process. To address these questions, we developed a high-quality en face technique that enables visualizing of leukocytes and endothelial cells simultaneously following an endoluminal scratch wound injury of the mouse carotid artery. We discovered that regrowing endothelium forms a broad proliferative front accompanied by CD11c⁺ leukocytes. Functionally, the leukocytes were dispensable for the initial migratory response of the regrowing endothelial sheet, but critical for the subsequent formation and maintenance of a front zone with high cellular density. Marker expression analyses, genetic fate mapping, phagocyte targeting experiments, and mouse knock-out experiments indicate that the CD11c⁺  leukocytes were mononuclear phagocytes with an origin from both Ly6C^high and Ly6C^low monocytes. In conclusion, CD11c⁺ mononuclear phagocytes are essential for a proper endothelial regrowth following arterial endoluminal scratch injury. Promoting the endothelial-preserving function of CD11c⁺  leukocytes may be a strategy to enhance endothelial repair following surgical and endovascular procedures.

Predictive Value of Mean Platelet Volume in Saphenous Vein Graft Disease

OBJECTIVE

To determine whether mean platelet volume (MPV), platelet distribution width (PDW), and platelet count could be used as determinants of mortality following coronary artery bypass graft (CABG) surgery and patency of saphenous vein grafts (SVG).

METHODS

The records of 128 patients who underwent emergency or elective coronary angiography after CABG surgery, and who died at an early stage were retrospectively reviewed. Patients were divided into three groups as early death, no SVG disease (SVGD), and SVGD group. MPV, PDW, and platelet count were evaluated at different times.

RESULTS

MPV was significantly higher in the stenotic group than in the nonstenotic group (9.7±1.8 fl and 8.2±0.9 fl, P<0.05). The postoperative MPV ratio was found to be higher in the stenotic group when compared to the preoperative period (9.6±1.8 fl and 7.8±0.9 fl, P<0.05). MPV values were also found to be higher in patients who died during the early stage than in surviving patients (9.4±1.9 fl and 8.0±1.0 fl, P<0.05). There was no statistically significant difference regarding platelet count and PDW ratios between the early deaths group and surviving patients. An MPV value higher than 10.6 predicted SVGD with 85% sensitivity and 45% specificity; and an MPV higher than 7.9 predicted early death with 80% sensitivity and 68% specificity were observed.

CONCLUSION

MPV may be a useful indicator for the prediction of SVGD and mortality following CABG surgery.

Antegrade cardioplegia as a possible cause of acute saphenous vein endothelial damage in patients undergoing on pump coronary artery bypass surgery

Background

The administration of antegrade cardioplegia through vein grafts after the completion of each distal anastomosis is a common practice. However, the cardioplegic solution may disrupt the vein endothelium and contribute to late vein graft atherosclerotic disease. This study aimed at evaluating the possible impact of the cardioplegic solution on vein graft endothelium.

Methods

Total of 52 patients (16 women and 36 men) aged 68±8.5 years old that underwent on pump coronary revascularization with at least one vein graft were enrolled. Sections of grafts from the greater saphenous vein were obtained prior to and after delivery of potassium antegrade cardioplegic solution through them. These sections were then examined histologically with immunochemical stain and CD34 index. The endothelial damage and length of vein specimens of both graft sections were evaluated.

Results

The endothelial damage of vein specimens appeared to be increased significantly with exposure to antegrade cardioplegia in male and female patients (P from Wilcoxon tests <0.001, for both genders). The increase in the length of vein specimens was significant too (P from Wilcoxon test <0.001 for men and P=0.001 for women).

Conclusions

Antegrade cardioplegia delivered through vein grafts causes substantial damage on vein endothelium. This may have an adverse effect on long-term graft patency.

Early animal model evaluation of an implantable contrast agent to enhance magnetic resonance imaging of arterial bypass vein grafts

Background Non-invasive monitoring of autologous vein graft (VG) bypass grafts is largely limited to detecting late luminal narrowing. Although magnetic resonance imaging (MRI) delineates vein graft intima, media, and adventitia, which may detect early failure, the scan time required to achieve sufficient resolution is at present impractical. Purpose To study VG visualization enhancement in vivo and delineate whether a covalently attached MRI contrast agent would enable quicker longitudinal imaging of the VG wall. Material and Methods Sixteen 12-week-old male C57BL/6J mice underwent carotid interposition vein grafting. The inferior vena cava of nine donor mice was treated with a gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA)-based contrast agent, with control VGs labeled with a vehicle. T1-weighted (T1W) MRI was performed serially at postoperative weeks 1, 4, 12, and 20. A portion of animals was sacrificed for histopathology following each imaging time point. Results MRI signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were significantly higher for treated VGs in the first three time points (1.73 × higher SNR, P = 0.0006, and 5.83 × higher CNR at the first time point, P = 0.0006). However, MRI signal enhancement decreased consistently in the study period, to 1.29 × higher SNR and 2.64 × higher CNR, by the final time point. There were no apparent differences in graft morphometric analyses in Masson's trichrome-stained sections. Conclusion A MRI contrast agent that binds covalently to the VG wall provides significant increase in T1W MRI signal with no observed adverse effects in a mouse model. Further optimization of the contrast agent to enhance its durability is required.

Outcomes of Fractional Flow Reserve-Based Deferral in Saphenous Vein Graft Narrowing

Fractional flow reserve (FFR) has been shown to improve clinical decision-making for revascularization in intermediate coronary stenosis in native coronary arteries of patients with stable coronary disease. However, its use for saphenous vein graft (SVG) lesions has not been well validated. We sought to determine the prognostic value of deferring intervention in lesions with FFR >0.8 in SVG lesions. Clinical, angiographic, and hemodynamic variables and long-term outcomes were recorded in consecutive patients in whom percutaneous coronary intervention was deferred based on an FFR >0.8 for intermediate native coronary artery or SVG stenosis. Thirty-three patients underwent FFR of SVG lesions and were compared with 532 patients who underwent native vessel FFR during the same period. There were no differences in age (66.6 [interquartile range, IQR 63 to 76] vs 65 years [IQR 61 to 70]; p = 0.12), diabetes (41% vs 50%; p = 0.35), or hypertension (94% vs 97%; p = 0.71). During a median follow-up of 3.2 years (IQR 1.7 to 4.6 years) major adverse cardiac event was significantly higher in SVG group (36% vs 21%; log rank p = 0.01). Similarly, the rate of target vessel failure was significantly higher in the SVG group (27% vs 14%; p = 0.01). Deferred SVG lesions had the worst survival free of target vessel failure compared with deferred native lesions in both patients with and without previous CABG. An SVG lesion was an independent predictor of major adverse cardiac events on Cox proportional hazards analysis (hazard ratio 2.26; confidence interval 1.19, 4.28; p = 0.01). In conclusion, nonischemic FFR carries a significantly worse prognosis in SVG compared with non-SVG lesions. Caution is warranted in utilizing FFR for clinical decision-making in SVG lesions.

Rationale for administering beta-blocker therapy to patients undergoing coronary artery bypass surgery: a systematic review

INTRODUCTION

Secondary preventative therapies are essential for patients undergoing coronary artery bypass graft (CABG) surgery to optimize perioperative and long-term outcomes. Beta-blockers are commonly used to treat patients with coronary artery disease and congestive heart failure (CHF), but their role for CABG patients remains unclear. The goal of this systematic review was to evaluate the rationale for administering beta-blockers to the CABG population and to assess their efficacy before and after coronary surgical revascularization.

AREAS COVERED

A systematic literature review was performed to retrieve relevant articles from the PubMed database published between 1985 and 2017.

EXPERT OPINION

Outside of the surgical field, strong evidence supports the use of beta-blockers for patients with a history of previous myocardial infarction (MI) or CHF. For the CABG population, studies have suggested that perioperative beta-blocker therapy is beneficial, with an associated reduction in mortality, particularly among those with a history of previous MI or CHF. Beta-blocker administration has also clearly been shown to lower the rate of new-onset postoperative atrial fibrillation after CABG. Among the different types of beta-blockers, perioperative carvedilol appears to be the most beneficial. In the absence of contraindications, nearly all CABG patients are candidates for perioperative beta-blocker therapy.

A comparison of postoperative morphometric and hemodynamic changes between saphenous vein and left internal mammary artery grafts

There is higher long‐term failure of the saphenous vein graft (SVG) compared with the left internal mammary artery (LIMA) graft, which is affected by the hemodynamic environment. A comprehensive analysis of postoperative structure‐function changes is important to study the atherogenesis in the SVG. A comparison of morphometric and hemodynamic parameters was carried out between LIMA grafts and SVGs and between different time points postoperatively. Various parameters were obtained from the image reconstruction and flow simulation in patients, who underwent CT exams for ~1 year, 5 and 10 years after revascularization. Morphometric data showed a decrease in lumen size in the entire SVG and anastomosis of different patients in a sequence of ~1 year, 5 and 10 years postoperatively despite negligible changes of LIMA size. Computational results indicated the fourfold increased surface area ratio (SAR) of low time‐averaged wall shear stress (TAWSS) in the SVG and anastomosis at postoperative 10 years than that at postoperative ~1 year. The SAR of high TAWSS gradient (TAWSSG) at the distal anastomosis between SVG and coronary arteries was significantly higher (14 ± 9% vs. 6 ± 8%) than that in the LIMA group at postoperative ~1 year. There were strong correlations between morphometric and hemodynamic parameters in the SVG and distal anastomosis at various time points postoperatively, which showed deterioration relevant to persistent diffuse diseases at postoperative ~10 years.