Implications of Hemodialysis in Patients Undergoing Coronary Artery Bypass Grafting

A Single-Cell Survey of Cellular Heterogeneity in Human Great Saphenous Veins

Background: The great saphenous vein (GSV) is the most commonly used conduit for coronary arterial bypass graft. However, the status of the GSV, including metabolic dysfunction such as diabetes mellitus (DM) complication, is strongly associated with vein graft failure (VGF). To date, the molecular mechanism underlying VGF remains elusive. Detailed characterization of the cellular components and corresponding expression regulation in GSVs would be of great importance for clinical decision making to reduce VGF. Methods: To this end, we performed single-cell RNA sequencing to delineate cellular heterogeneity in three human GSV samples. Results: Scrutinization of cellular composition and expression revealed cell diversity in human GSVs, particularly endothelial cells (ECs). Our results unraveled that functional adaptation drove great expression differences between venous ECs and valvular ECs. For instance, cell surface receptor ACKR1 demarcated venous Ecs, whereas ACRK3/ACKR4 were exclusively expressed by valvular ECs. Differential gene expression analysis suggested that genes highly expressed in venous ECs were mainly involved in vasculature development and regulation of leukocyte adhesion, whereas valvular ECs have more pronounced expression of genes participating in extracellular matrix organization, ossification and platelet degranulation. Of note, pseudo-time trajectory analysis provided in silico evidence indicating that venous ECs, valvular ECs and lymphatic vessels were developmentally connected. Further, valvular ECs might be an importance source for lymphatic vessel differentiation in adults. Additionally, we found a venous EC subset highly expressing IL6, which might be associated with undesirable prognosis. Meanwhile, we identified a population of ANGPTL7+ fibroblasts (FBs), which may be profibrotic and involved in insulin resistance in human GSVs. Additionally, our data suggest that immune cells only accounted for a small fraction, most of which were macrophages. By assessing the intertwined remodeling in metabolic dysfunction that potentially increases the gene expression regulatory network in mural cells and leukocytes, we found that transcription factor KLF9 likely operated a proinflammatory program, inducing the transcription of metallothionein proteins in two mural cell subsets and proinflammatory immune cells. Lastly, cellular communication analysis revealed that proinflammatory signaling, including TRAIL, PVR, CSF and GDF, were uniquely activated in patients with metabolic dysfunction. Conclusions: Our results identified critical cell-specific responses and cellular interactions in GSVs. Beyond serving as a repertoire, this work illustrates multifactorial likelihood of VGF.

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.

Coronary Artery Bypass: Review of Surgical Techniques and Impact on Long-Term Revascularization Outcomes

Coronary revascularization for multivessel disease remains a common and costly source of hospitalizations in the United States. Surgical techniques influence outcomes for coronary bypass and also affect the need for percutaneous coronary intervention in the future. As more radial access has been used for coronary angiography, consideration for use of the radial artery as a surgical conduit remains unclear. Saphenous vein grafts are commonly used for coronary bypass, however long-term patency remains suboptimal, and is also associated with a higher risk of adverse events with percutaneous coronary intervention. Thus, understanding the interplay between coronary bypass techniques and percutaneous coronary intervention has become increasingly important.

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.

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.

Conditional long-term survival following minimally invasive robotic mitral valve repair: a health services perspective

BACKGROUND

Conditional survival is defined as the probability of surviving an additional number of years beyond that already survived. The aim of this study was to compute conditional survival in patients who received a robotically assisted, minimally invasive mitral valve repair procedure (RMVP).

METHODS

Patients who received RMVP with annuloplasty band from May 2000 through April 2011 were included. A 5- and 10-year conditional survival model was computed using a multivariable product-limit method.

RESULTS

Non-smoking men (≤65 years) who presented in sinus rhythm had a 96% probability of surviving at least 10 years if they survived their first year following surgery. In contrast, recent female smokers (>65 years) with preoperative atrial fibrillation only had an 11% probability of surviving beyond 10 years if alive after one year post-surgery.

CONCLUSIONS

In the context of an increasingly managed healthcare environment, conditional survival provides useful information for patients needing to make important treatment decisions, physicians seeking to select patients most likely to benefit long-term following RMVP, and hospital administrators needing to comparatively assess the life-course economic value of high-tech surgical procedures.

Conditional survival of heart failure patients after coronary artery bypass grafting

AIMS

Conditional survival is defined as the probability of surviving an additional number of years beyond that already survived. The aim of this study was to estimate conditional survival in heart failure patients after coronary artery bypass grafting (CABG).

METHODS

Heart failure patients with multivessel coronary artery disease undergoing first-time, isolated CABG between 1992 and 2011 were included in this study. Conditional survival estimates were computed for 1, 5, and 10 years after already surviving 0.5, 1, 2, 3, 4, and 5 years.

RESULTS

Compared with traditional survival estimates, conditional survival was consistently higher at all time periods. The overall 2-year adjusted survival estimate was 84% compared with the 1-year conditional survival rate of 95% for 1-year survivors. Similarly, the overall 10-year adjusted survival rate was 36% from the time of surgery compared with the 5-year conditional survival of 54% for patients who had survived 5 years.

CONCLUSION

Conditional survival provides a more accurate estimate of long-term survival in heart failure patients who have already survived for a certain amount of time after CABG. This information is useful for patients and physicians who manage their long-term care.

Increased coronary artery disease severity in black women undergoing coronary bypass surgery

Race and sex disparities are believed to play an important role in heart disease. The purpose of this study was to examine the association between race, sex, and number of diseased vessels at the time of coronary artery bypass grafting (CABG), and subsequent postoperative outcomes. The 13,774 patients undergoing first-time, isolated CABG between 1992 and 2011 were included. Trend in the number of diseased vessels between black and white patients, stratified by sex, were analyzed using a Cochran-Armitage trend test. Models were adjusted for age, procedural status (elective vs. nonelective), and payor type (private vs. nonprivate insurance). Black female CABG patients presented with an increasingly greater number of diseased vessels than white female CABG patients (adjusted P(trend) = 0.0021). A similar trend was not observed between black and white male CABG patients (adjusted P(trend) = 0.18). Black female CABG patients were also more likely to have longer intensive care unit and hospital lengths of stay than other race-sex groups.Our findings suggest that black female CABG patients have more advanced coronary artery disease than white female CABG patients. Further research is needed to determine the benefit of targeted preventive care and preoperative workup for this high-risk group.

Risk-adjusted survival after coronary artery bypass grafting: implications for quality improvement

Mortality represents an important outcome measure following coronary artery bypass grafting. Shorter survival times may reflect poor surgical quality and an increased number of costly postoperative complications. Quality control efforts aimed at increasing survival times may be misleading if not properly adjusted for case-mix severity. This paper demonstrates how to construct and cross-validate efficiency-outcome plots for a specified time (e.g., 6-month and 1-year survival) after coronary artery bypass grafting, accounting for baseline cardiovascular risk factors. The application of this approach to regional centers allows for the localization of risk stratification rather than applying overly broad and non-specific models to their patient populations.

The effect of preoperative β-blocker use and race on long-term survival after coronary artery bypass grafting

OBJECTIVE

To date, racial differences in the long-term survival of coronary artery bypass grafting (CABG) patients who receive preoperative β-blockers have not been specifically examined. The purpose of this study was to examine the effect of preoperative β-blockers on long-term survival among black CABG patients and to compare the magnitude of this effect with white patients.

DESIGN

A retrospective cohort study.

SETTING

A tertiary referral heart hospital.

PARTICIPANTS

13,354 patients undergoing CABG between 1992 and 2011.

MEASUREMENTS AND MAIN RESULTS

Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. A total of 1,448 (62%) black and 6,094 (55%) white patients had a history of preoperative β-blocker use. Among black patients, those receiving β-blockers survived longer than those not receiving β-blockers (adjusted HR = 0.77, 95% CI = 0.67-0.88). The survival advantage was comparable to that observed among white patients (adjusted HR = 0.88, 95% CI = 0.82-0.93).

CONCLUSION

Black CABG patients benefited from preoperative β-blockers and the magnitude of the effect was comparable to that among white patients.

Racial differences in survival among hemodialysis patients after coronary artery bypass grafting

The aim of this study was to examine racial differences in long-term survival among hemodialysis patients after coronary artery bypass grafting (CABG). To our knowledge this has not been previously addressed in the literature. Black and white hemodialysis patients undergoing first-time, isolated CABG procedures between 1992 and 2011 were compared. Survival probabilities were computed using the Kaplan-Meier product-limit method and stratified by race. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. A total of 207 (2%) patients were on hemodialysis at the time of CABG. White (n = 80) hemodialysis patients had significantly decreased 5-year survival compared with black (n = 127) patients (adjusted HR = 1.9, 95% CI = 1.2-2.8). Our finding provides useful outcome information for surgeons, primary care providers, and their patients.