A meta-analysis comparing bilateral internal mammary artery with left internal mammary artery for coronary artery bypass grafting

Sequential composite BIMA grafting for 3v-CAD: factors that predict successful outcome of the one-inflow and two-inflow revascularization techniques

OBJECTIVE

The effect of one-inflow and two-inflow coronary surgical revascularization techniques inclosing skeletonized double mammary artery (BIMA) as T-graft on outcome is studied.

METHODS

Early ad mid-term outcome of complete BIMA revascularization (C-T-BIMA) versus left-sided BIMA with right-sided aorto-coronary bypass (L-T-BIMA + R-CABG) is quantified and analyzed by multivariate logistic regression, Cox-regression, and Kaplan-Meier analysis in a series of 204 consecutive patients treated for triple-vessel coronary disease (3v-CAD).

RESULTS

The L-T-BIMA + R-CABG technique (n = 104) enables higher number of total (4.02 ± 0.87 vs. 3.71 ± 0.69, p = 0.015) and right-sided (1.21 ± 0.43 vs. 1.02 ± 0.32, p = 0.001) coronary anastomoses, improves total bypass flow (125.88 ± 92.41 vs. 82.50 ± 49.26 ml, p < 0.0001) and bypass flow/anastomosis (31.83 ± 23.9 vs.22.77 ± 14.23, p = 0.001), and enhances completeness of revascularization (84% vs.69%, p = 0.014) compared to C-T-BIMA strategy (n = 100), respectively. Although the incidence of MACCE was comparable in the two groups (8% vs.1.2%, p = 0.055), the progression of functional mitral regurgitation (FMR) was significantly lower after L-T-BIMA + R-CABG, then after C-T-BIMA (47% vs.64%, p = 0.017). The use of C-T-BIMA-technique (HR = 4.2, p = 0.01) and preoperative RCA occlusion (HR = 3.006, p = 0.023) predicted FMR progression, whereas L-T-Graft + R-CABG technique protected against it (X2 = 14.04, p < 0.0001) independent of the anatomic and clinical complexity (Syntax score I: HR = 16.2, p = 0.156, Syntax score II: HR = 1.901, p = 0.751), of early- (0.96% vs.2%, p = 0.617) and mid-term mortality (5.8% vs.4%, p = 0.748) when compared to C-T-BIMA, respectively.

CONCLUSIONS

The two-inflow coronary revascularization by L-T-BIMA + R-CABG better protects against FMR progression without increasing MACCE and mortality. Older patients with RCA occlusion and reduced LV-EF benefit most from the two-inflow L-T-BIMA + R-CABG technique. Younger 3v-CAD patients with normal LV-EF can preferentially be managed with the one-inflow C-T-BIMA; however, long-term outcome remains to be revealed.

Coronary artery bypass grafting using bilateral internal thoracic arteries in patients with diabetes and obesity: A systematic review and meta-analysis

Background

Patients with diabetes and obesity are at higher risk of adverse long-term outcomes following coronary artery bypass grafting. The use of bilateral internal thoracic arteries (BITA) can potentially offer survival benefit in higher risk patients compared to single internal thoracic artery (SITA), but BITA is not routinely used due to lack of clear evidence of efficacy and concerns over sternal wound complications.

Methods

Medline, Embase and the Cochrane Library were searched for studies comparing the efficacy and safety of BITA and SITA grafting in patients with diabetes and obesity. Meta-analysis of mortality and sternal wound complications was performed.

Results

We identified eight observational and ten propensity matched studies, and one RCT, comparing BITA and SITA which included patients with diabetes (n = 19,589); two propensity matched studies and one RCT which included patients with obesity (n = 6,972); mean follow up was 10.5 and 11.3 years respectively. Meta-analysis demonstrated a mortality reduction for BITA compared to SITA in patients with diabetes (risk ratio [RR] 0.79; 95% confidence interval [CI] 0.70-0.90; p = 0.0003). In patients with obesity there was a non-significant reduction in mortality in the BITA group (RR 0.73, 95% CI 0.47-1.12; p = 0.15). There was a significantly higher rate of sternal wound complications following BITA observed in patients with diabetes (RR 1.53, 95% CI 1.23-1.90; p = 0.0001) and obesity (RR 2.24, 95% CI 1.63-3.07; p < 0.00001).

Conclusions

BITA is associated with better long-term survival in patients with diabetes. The effects of BITA grafting in patients with obesity are uncertain. BITA is associated with higher rates of sternal wound complications compared to SITA in both patients with diabetes and obesity.

Competitive Flow: Closure of Internal Thoracic Artery Graft After Successful Coronary Artery Bypass Graft Surgery

The internal thoracic artery has a patency rate of 85%-95% at 10-15 years post coronary artery bypass graft surgery. Development of total occlusion of the internal thoracic artery within a short period (< 6 months) after the surgery is exceedingly rare. However, competitive flow between the native vessel and the conduit internal thoracic artery, or competitive flow between the 2 conduit internal thoracic arteries in a multiple arterial grafting procedure can jeopardize 1 of the 2 conduit internal thoracic arteries. We report the cases of 2 patients who had bilateral internal thoracic artery grafts, with total occlusion of 1 of the 2 grafts within a short period (6 months) after successful coronary artery bypass graft surgery.

Total Arterial Coronary Bypass Graft Surgery is Associated with Better Long-Term Survival in Patients with Multivessel Coronary Artery Disease: a Systematic Review with Meta-Analysis

INTRODUCTION

The benefit of total arterial revascularization (TAR) in coronary artery bypass grafting (CABG) remains a controversial issue. This study sought to evaluate whether there is any difference on the long-term results of TAR and non-TAR CABG patients.

METHODS

The Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica dataBASE (EMBASE), Cochrane Central Register of Controlled Trials (CENTRAL/CCTR), Clinical Trials.gov, Scientific Electronic Library Online (SciELO), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), and Google Scholar databases were searched for studies published by October 2020. Randomized clinical trials and observational studies with propensity score matching comparing TAR versus non-TAR CABG were included. Random-effects meta-analysis was performed. The current barriers to implementation of TAR in clinical practice and measures that can be used to optimize outcomes were reviewed.

RESULTS

Fourteen publications (from 2012 to 2020) involving a total of 22,746 patients (TAR: 8,941 patients; non-TAR: 13,805 patients) were included. The pooled hazard ratio (HR) for long-term mortality (over 10 years) was lower in the TAR group than in the non-TAR group (random effect model: HR 0.676, 95% confidence interval 0.586-0.779, P<0.001). There was evidence of low heterogeneity of treatment effect among the studies for mortality, and none of the studies had a particular impact on the summary result. The result was not influenced by age, sex, or comorbidities. We identified low risk of publication bias related to this outcome.

CONCLUSION

This review found that TAR presents the best long-term results in patients who undergo CABG. Given that many patients are likely to benefit from TAR, its use should be encouraged.

Quantitative estimation of LIMA blood flow between extraluminal papavarine vs extraluminal papavarine plus intraluminal vasodilator cocktail in CABG patients

Objective:

In this study, we aimed at a comparative quantitative estimation of the difference in LIMA blood flow between LIMAs treated with topical papaverine alone and LIMAs treated with a combination of topical papaverine plus an intraluminal cocktail of papaverine, nitroglycerine, and milrinone.

Methods:

Nearly 50 consecutive patients with similar demographics undergoing elective on-pump CABG were recruited for the study. After pedicled LIMA harvest, topical papaverine was sprayed on the pedicle and kept enveloped in papaverine soaked gauze. LIMA flow was then estimated. Later, intraluminal vasodilator solution of papaverine, NTG, milrinone, and heparinized blood were instilled in LIMA, and LIMA flows were estimated.

Results:

The mean LIMA flows with topical papaverine alone was 47.19 mL/min whereas the mean LIMA flows with topical papaverine plus intraluminal cocktail was 104 mL/min. There was a significant difference between the two flows as their mean was 56.815 mL/min and the paired t-test for significance had a P value of 0.0001.

Conclusion:

There was a significant difference in the LIMA flow when the LIMA had been treated with the intraluminal instillation of the vasodilator cocktail in addition to the topical application of papaverine solution. Therefore, intraluminal vasodilator cocktail of milrinone, NTG, and papaverine mixed with heparinized blood in addition to topical papaverine is a simple and effective method for LIMA preparation in CABG.

Preserving the endothelium in saphenous vein graft with both conventional and no-touch preparation

Background

Despite the inferior patency compared to arterial grafts, a saphenous vein graft (SVG) is widely used for coronary artery bypass grafting (CABG). A lower atherosclerosis rate and higher patency have been reported for SVG obtained via the no-touch technique (NT) than via conventional preparation (CV). Although CV-mediated endothelial dysfunction is implied, the precise mechanism underlying the higher patency with NT is poorly understood.

Methods

Human residual SVGs during CABG and SVG sections after autopsy were analyzed. The endothelial surface was observed using scanning electron microscopy (SEM) and blindly compared between CV and NT. The endothelial integrity was also analyzed with immunohistochemistry.

Results

Unexpectedly, the hyperfine structure on SEM was comparable between CV and NT before grafting, and microvillus, a characteristic of endothelium, was indistinguishable between them. Von Willebrand Factor, an endothelial marker, was equally detected throughout the vascular wall in both groups from residual and postmortem sections.

Conclusions

The morphological integrity of the endothelium was successfully preserved in SVG with CV, even at an ultrastructural level. Although its functionality remains to be addressed, other factors than the endothelium may be involved in the high patency obtained by NT. The present findings suggest that the characteristics of NT and surgical methodology should be reconsidered.

The use of both internal thoracic arteries for coronary revascularization increases the estimate of post-operative lower limb ischemia in patients with peripheral artery disease

Background

Patients with a history of peripheral arterial disease (PAD) undergoing coronary artery bypass grafting (CABG) exhibit higher rates of complications. There are conflicting data on the survival benefits for bilateral thoracic artery (BITA) grafting compared with left internal thoracic artery (LITA) CABG in patients with PAD. The aim of the study was to explore the influence of the use of BITA grafts vs. LITA for CABG on post-operative acute lower limb ischemia (ALLI) and main post-operative complications in patients with concomitant PAD.

Methods

We used a propensity-score (PS) based analysis to compare outcomes between the two surgical procedures, BITA and LITA. The inverse probability of treatment weighting PS technique was applied to adjust for pre- and intra-operative confounders, and to get optimal balancing of the pre-operative data. The primary outcome was the estimate of postoperative ALLI. Secondary outcomes included overall death and death of cardiac causes within 30 days of surgery, stroke and acute kidney disease (AKD).

Results

The study population consisted of 1961 patients. The LITA procedure was performed in 1768 patients whereas 193 patients underwent a BITA technique. The estimate of ALLI was 14% higher in the BITA compared to the LITA (p < 0.001) group. Thirty-day mortality, cardiac death, occurrence of stroke and AKI did not differ significantly between the groups.

Conclusions

The use of both ITAs led to a significant increase in ALLI. This result was most likely caused by the complete disruption of the ITA collateral providing additional blood supply to the lower extremities. Based on our data, BITA should be used with extreme caution in PAD patients. Further research on this topic is necessary to confirm our findings.

Sternal wound closure in the current era: the need of a tailored approach

OBJECTIVE

Median sternotomy remains the most common access to perform cardiac surgery procedures. However, the experience of the operating surgeon remains a crucial factor during sternal closure to avoid potential complications related to poor sternal healing, such as mediastinitis. Considering the lack of major randomized controlled trials and the heterogeneity of the current literature, this narrative review aims to summarize the different techniques and approaches to sternal closure with the aim to investigate their reflections into clinical outcomes and to inform the choice on the most effective closure method after median sternotomy.

METHODS

A literature search through PubMed, Embase, EBSCO, Cochrane database of systematic reviews, and Web of Science from its inception up to April 2019 using the following search keywords in various combinations: sternal, sternotomy, mediastinitis, deep sternal wound infection, cardiac surgery, closure.

RESULTS

Single wire fixation methods, at present, seems the most useful method to perform sternal closure in routine patients, although patients with a fragile sternum might benefit more from a figure-of-eight technique. In high-risk patients (e.g. chronic pulmonary disease, obesity, bilateral internal mammary artery harvesting, diabetes, off-midline sternotomy), rigid plate fixation is currently the most effective method, if available; alternatively, weave techniques could be used.

CONCLUSION

The choice among the sternal closure techniques should be mainly inspired and tailored on the patient's characteristics, and correct judgement and experience play a pivotal role. A decisional algorithm has been proposed as an attempt to overcome the absence of specific guidelines and to guide the operative approach. This operative approach might be used also in non-cardiac procedure in which median sternotomy is required, such as in case of thoracic surgery.

Skeletonisation contributing to a reduction of sternal wound complications: a retrospective study in OPCAB patients

Background

Sternal wound complications (SWC) are a rare but potentially life-threatening complication after coronary artery bypass grafting (CABG) surgery. Especially the use of bilateral IMA (BIMA) grafts as opposed to single IMA (SIMA) grafts is associated with an increased risk of SWC. Skeletonised harvesting has been proposed to reduce this risk. The purpose of this study was to retrospectively investigate the effect of skeletonisation on SWC after off-pump coronary artery bypass grafting (OPCAB) in a centre with a high volume of off-pump procedures and high frequencies of BIMA.

Methods

From January 2010 to November 2016, 1900 consecutive patients underwent OPCAB surgery at the University Hospitals of Leuven. The first group (n = 1487) received non-skeletonised IMA grafts, whereas the second group (n = 413) received skeletonised grafts. Optimal wound management was pursued in all patients. A new four-grade classification for SWC was developed. Incidence and grade of SWC as well as overall survival were assessed.

Results

Analysis of diabetic patients showed a lower incidence of SWC in the skeletonised (12/141, 8.5%) compared to the non-skeletonised group (82/414, 19.8%) [odds ratio 0.46, 95% confidence interval (0.23;0.88), p = 0.019] as well as a lower grade [0.45 (0.24;0.871), p = 0.018]. There was no significant effect on overall survival [0.67 (0.19;2.32), p = 0.529]. Subanalysis of this population revealed that the observed effects were most prominent in patients receiving BIMA grafts, with 6/56 (10.7%) SWC in the skeletonised and 62/252 (24.6%) in the non-skeletonised group [0.37 (0.15;0.90), p = 0.028 for incidence], as well as a lower grade [0.36 (0.15;0.88), p = 0.025]. These advantages were not significant in diabetic patients receiving SIMA grafts nor in the full study population.

Conclusions

This study, using a more sensitive classification of SWC, shows in a large group of patients that, in combination with optimized wound management, the skeletonisation technique is associated with a clear reduction in the incidence and grade of SWC in diabetic patients receiving BIMA grafts. This encourages the extension of BIMA use in OPCAB to this risk population.

Electronic supplementary material

The online version of this article (10.1186/s13019-019-0985-9) contains supplementary material, which is available to authorized users.

Long-term Outcomes of Multiple Arterial Coronary Artery Bypass Grafting: A Population-Based Study of Patients in British Columbia, Canada

Importance

Although the long-term survival advantage of multiple arterial grafting (MAG) vs the standard use of left internal thoracic artery (LITA) supplemented by saphenous vein grafts (LITA+SVG) has been demonstrated in several observational studies, to our knowledge its safety and other long-term clinical benefits in a large, population-based cohort are unknown.

Objective

To compare the safety and long-term outcomes of MAG vs LITA+SVG among overall and selected subgroups of patients.

Design, Setting, and Participants

In this population-based observational study, we included 20 076 adult patients with triple-vessel or left-main disease who underwent primary isolated coronary artery bypass grafting (MAG, n = 5580; LITA+SVG, n = 14 496) in the province of British Columbia, Canada, from January 2000 to December 2014, with follow-up to December 2015. We performed propensity-score analyses by weighting and matching and multivariable Cox regression to minimize treatment selection bias.

Exposures

Multiple arterial grafting or LITA+SVG.

Main Outcomes and Measures

Mortality, repeated revascularization, myocardial infarction, heart failure, and stroke.

Results

Of 5580 participants who underwent MAG, 586 (11%) were women and the mean (SD) age was 60 (8.7) years. Of 14 496 participants who underwent LITA+SVG, 2803 (19%) were women and the mean (SD) age was 68 (8.9) years. The median (interquartile range) follow-up time was 9.1 (5.1-12.6) years and 8.1 (4.5-11.7) years for the groups receiving MAG and LITA+SVG, respectively. Compared with LITA+SVG, MAG was associated with reduced mortality rates (hazard ratio [HR], 0.79; 95% CI, 0.72-0.87) and repeated revascularization rates (HR, 0.74; 95% CI, 0.66-0.84) in 15-year follow-up and reduced incidences of myocardial infarction (HR, 0.63; 95% CI, 0.47-0.85) and heart failure (HR, 0.79; 95% CI, 0.64-0.98) in 7-year follow-up. The long-term benefits were coherent by all 3 statistical methods and persisted among patient subgroups with diabetes, obesity, moderately impaired ejection fraction, chronic obstructive pulmonary disease, peripheral vascular disease, or renal disease. Multiple arterial grafting was not associated with increased morbidity or mortality rates at 30 days overall or within patient subgroups.

Conclusions and Relevance

Compared with LITA+SVG, MAG is associated with reduced mortality, repeated revascularization, myocardial infarction, and heart failure among patients with multivessel disease who are undergoing coronary artery bypass grafting without increased mortality or other adverse events at 30 days. The long-term benefits consistently observed across multiple outcomes and subgroups support the consideration of MAG for a broader spectrum of patients who are undergoing coronary artery bypass grafting in routine practice.

Outcome of Robot-Assisted Bilateral Internal Mammary Artery Grafting via Left Pleura in Coronary Bypass Surgery

Studies are extremely limited for the investigation of the clinical outcome of da Vinci robot-assisted bilateral internal mammary artery (BIMA) grafting in coronary artery bypass grafting (CABG) surgery. This study aimed to explore the short-term outcome of da Vinci robot-assisted BIMA grafting through the left pleural space. Relevant data were collected from patients with multi-vessel coronary artery disease receiving two kinds of CABG: a group of patients receiving da Vinci robot-assisted CABG with BIMA grafting, and another group of patients receiving sternotomy CABG with BIMA grafting. Primary endpoints, which included cardiovascular and renal endpoints, were analyzed between the groups using the chi-square test, analysis of variance test, and Kaplan-Meier analysis. Compared with the conventional group (n = 22), the robotic group (n = 22) had a significantly longer operation time (12.7 ± 1.7 vs. 8.5 ± 1.5 hours; p < 0.01) and a marginally lower mean of serum creatinine at baseline (1.2 ± 0.3 vs. 2.0 ± 1.7 mg/dL; p = 0.04). Primary endpoints (5, 22.7% vs. 12, 54.5%; p = 0.03) and renal endpoints (1, 4.5% vs. 7, 31.8%; p = 0.02) at six months were significantly reduced in the robotic group compared with the conventional group. There were no differences in cardiovascular endpoints at six months between the groups (1, 4.5% vs. 0; p = 1.00). The data showed that da Vinci robot-assisted BIMA grafting was safe, with equal cardiovascular events and lowered renal events at six months, as compared to conventional sternotomy BIMA grafting, despite the longer procedure time. The short-term study suggests that da Vinci robot-assisted BIMA grafting may be considered a favorable surgical option for patients with severe coronary artery disease.

Long-term outcomes of multiple and single arterial off-pump coronary artery bypass grafting

Background

To compare the clinical outcomes between multiple arterial (MA) and single arterial (SA) off-pump coronary artery bypass grafting (OPCAB) when applied to left main coronary disease or three-vessel disease.

Methods

A total of 537 patients with left main coronary disease or three-vessel disease underwent MA OPCAB (n=114) or SA OPCAB (n=423) in our center from January 2006 to December 2008. The propensity score matching (PSM) was used to obtain the risk-adjusted outcome. Both the perioperative and long-term results were analyzed.

Results

The median follow-up time was 117 months (interquartile range, 110 to 128 months). There was no statistical difference in postoperative mortality and the volume of drainage. The intensive care unit (ICU) length of stay (LOS) of the MA group was shorter than that of the SA group {1 [1-2] vs. 2 [1-3], P=0.001). In the long term, the mortality (5.7% vs. 17.5%, P=0.006), cardiac mortality (1.0% vs. 8.8%, P=0.008), fatal myocardial infarction (MI) rate (0.0% vs. 6.1%, P=0.015) and incidence of readmission for heart failure (19.8% vs. 37.7%, P=0.003) were lower in the MA group than in the SA group. The distributions of NYHA class (P<0.001) and CCS class (P<0.001) were better in the MA group than in the SA group. There was no significant difference in other outcomes. These results were consistent with the K-M curves of freedom from the adverse events.

Conclusions

MA OPCAB was as safe as SA OPCAB, providing better perioperative recovery and better long-term clinical outcomes in the treatment of left main coronary disease or three-vessel disease.

Bilateral internal thoracic artery use in coronary bypass surgery: is there a benefit?

Purpose

Over the past three decades, there have been a plethora of retrospective observational data and meta-analyses which support the hypothesis of improved clinical outcomes using bilateral internal thoracic arteries (BITA) when compared to saphenous vein grafts (SVGs). However, recently published results have brought this thinking into doubt. We discuss the existing literature on the subject and attempt to clarify the appropriate use of BITA in coronary artery bypass surgery (CABG).

Methods

A review of all existing meta-analyses on BITA was conducted to better understand the utility of BITA in CABG. A review of the largest randomized controlled trials on the subject was then compared to the observational data.

Results

In all existing meta-analyses, BITA shows a significant advantage over the use of a single internal thoracic artery (SITA) with SVGs. The two largest randomized controlled trials evaluating BITA failed to show a survival advantage and brought into question the complications associated with BITA.

Conclusions

At present, the use of multiple arterial grafts remains a reasonable choice, particularly in young patients, provided that their use does not increase the operative risk. Further evidence currently being collected may lend a definitive answer in the near future.

How I deploy arterial grafts

There are currently around one million coronary artery bypass graft (CABG) procedures performed worldwide annually and despite two decades of evidence to support the use of a second arterial graft, if not total arterial grafting, the stark reality is that in contemporary practice 80% of all grafts used for CABG are saphenous vein grafts (SVG). The following description of how I deploy arterial grafts has been developed over more than two decades of clinical practice and largely self-taught by a process of "trial and error" and most importantly dictated by "ease of use" rather than personal robust angiographic data of long-term patency (although there is other such existing data in the literature for some of these techniques). The fact that there are numerous potential variants of deploying multiple arterial grafts underpins the fact that there is no single operation that is ideal in every patient-it is not a case of "one size fits all" as would be the situation for the use of a single internal thoracic artery (ITA) and supplemental vein grafts.

No-touch vein grafts and the destiny of venous revascularization in coronary artery bypass grafting-a 25th anniversary perspective

Ischemic heart disease is currently the leading cause of death globally, with coronary artery bypass grafting among the most common operations performed worldwide. More extensive use of arterial grafts has been advocated because of their high long-term patency, long-term survival benefit, and freedom from reinterventions. Despite this, the saphenous vein is the most frequently used conduit in patients undergoing coronary artery bypass surgery since its introduction over 50 years ago. Consequently, the saphenous vein remains an indispensable conduit in coronary artery bypass grafting and maintaining its long-term patency is one of the most crucial challenges in cardiovascular surgery. This situation led to the development of the no-touch saphenous vein harvesting technique, where the vein is harvested completely with its pedicle of surrounding tissue. Several studies report a superior long-term patency rate, slower progression of atherosclerosis, and better clinical outcomes whilst employing no-touch harvesting technique. The success of the technique is multifactorial, including the decreased risk for graft spasm-and the need for manual distension-preservation of the vaso vasorum and an intact endothelium, reducing neointimal hyperplasia and subsequent atherosclerosis. Furthermore, the intact perivascular tissue, including the surrounding cushion of fat, may act as a "natural external stent", providing mechanical support preventing the graft from kinking. We are convinced that the use of arterial grafts, in combination with the no-touch saphenous vein graft, will significantly improve the results of coronary artery bypass grafting. This is important for achieving a comprehensive and evidence-based balance between the major treatment strategies of ischemic heart disease, explicitly coronary artery bypass grafting and percutaneous coronary intervention. The no-touch technique is becoming increasingly popular among surgeons, with further studies to be initiated worldwide.

Off-pump coronary artery bypass surgery with bilateral internal thoracic arteries: the Leipzig experience

Background

Contrasting results of recent randomized controlled trials (RCTs) comparing off-pump and on-pump coronary artery bypass graft (CABG) surgery, as well as the lack of evidence for any survival benefit of bilateral internal thoracic artery (ITA) grafting over single ITA use, has intensified the debate about the role of the off-pump technique and bilateral ITA use in CABG surgery. We therefore investigated our 15-year experience in off-pump CABG with bilateral ITA grafting and evaluated temporal trends in preoperative characteristics and postoperative outcomes.

Methods

Demographic, intra-operative, and outcome data of 1,199 consecutive patients undergoing off-pump CABG with bilateral ITA grafting was prospectively collected in a computerized database. Patients who underwent on-pump cardiac procedures and other extra-cardiac procedures were excluded from this study. Assessment of changes in perioperative characteristics and parameters with time was performed by dividing the whole cohort into three groups (2003-2007, 2008-2012, and 2013-2017) based on the year of surgery.

Results

The overall 30-day mortality was 0.6%, with no differences observed between the three time cohorts (0.6%, 0.7%, 0.5%; P=0.8). The perioperative stroke rate for whole cohort was 0.6% and demonstrated a significant reduction in the last two time cohorts (1%, 0.5%, 0.5%; P<0.0001). The overall incidence of deep sternal wound infections was 0.7%, but was marginally higher in the last time-cohort (0.6%, 0.5%, 0.9%; P=0.7). Overall survival for the entire cohort was 92.9%±1% and 78.9%±4% at 5 and 10 years follow-up, respectively. Older age at surgery and presence of peripheral vascular disease were the only predictors of late mortality.

Conclusions

Off-pump CABG with bilateral skeletonized ITAs is a safe operation and is associated with a low mortality and morbidity, which can be maintained in high volume center unit over a long period of time. The long-term survival of patients undergoing such an operation is excellent.

Fifty years of coronary artery bypass grafting

Coronary artery bypass grafting (CABG) remains the most common cardiac surgery performed today worldwide. The history of this procedure can be traced back for more than 100 years, and its development has been touched by several pioneers in the field of cardiac surgery, who have contributed with both their successes and failures. With ever increasing follow up and number of patients treated, thinking regarding optimal CABG technique evolves continually. This article reviews the history of CABG from its early experimental work to recent technological advances.

Unmeasured Confounders in Observational Studies Comparing Bilateral Versus Single Internal Thoracic Artery for Coronary Artery Bypass Grafting: A Meta-Analysis

Background

Observational studies suggest a survival advantage with bilateral single internal thoracic artery (BITA) versus single internal thoracic artery grafting for coronary surgery, whereas this conclusion is not supported by randomized trials. We hypothesized that this inconsistency is attributed to unmeasured confounders intrinsic to observational studies. To test our hypothesis, we performed a meta‐analysis of the observational literature comparing BITA and single internal thoracic artery, deriving incident rate ratio for mortality at end of follow‐up and at 1 year. We postulated that BITA would not affect 1‐year survival based on the natural history of coronary artery bypass occlusion, so that a difference between groups at 1 year could not be attributed to the intervention.

Methods and Results

We searched MEDLINE and Pubmed to identify all observational studies comparing the outcome of BITA versus single internal thoracic artery. One‐year and long‐term mortality for BITA and single internal thoracic artery were compared in the propensity‐score–matched (PSM) series, that is, the form of observational evidence less prone to confounders. Thirty‐eight observational studies (174 205 total patients) were selected for final comparison. In the 12 propensity‐score–matched series (34 019 patients), the mortality reduction for BITA was similar at 1 year and at the end of follow‐up (incident rate ratio, 0.70; 95% confidence interval, 0.60–0.82 versus 0.77; 95% confidence interval, 0.70–0.85; P for subgroup difference=0.43).

Conclusions

Unmeasured confounders, rather than biological superiority, may explain the survival advantage of BITA in observational series.

Total arterial revascularization in patients with acute myocardial infarction - feasibility and outcomes

BACKGROUND

In acute situations such as acute myocardial infarction (AMI) with indication for coronary artery bypass grafting (CABG), total arterial revascularization (TAR) is often rejected in favour of saphenous vein (SV) grafting, which is assumed to allow for quicker vessel harvesting, a simpler anastomosis technique, and thus quicker revascularization and fewer bleeding complications. The aim of this study was to evaluate whether reluctance to apply TAR in AMI is still justified from a technical point of view in the current era and whether superiority of TAR results is also evident in emergency patients with AMI undergoing CABG.

METHODS

In this retrospective analysis of 434 consecutive patients undergoing CABG for AMI with either TAR or with a combination of one internal mammary artery and SV grafts between 2008 and 2014, procedural data, short-term and mid-term outcome were compared. Propensity score matching of the groups was performed.

RESULTS

After propensity score matching, 250 patients were included in the analysis (TAR group: n = 98; SV group n = 152). The procedural time (TAR group: 211 min vs. SV group: 200 min, p = 0.46) did not differ between the groups. Erythrocyte transfusion rates were higher in the SV group (76% vs. 57%; p < 0.001). Rates of re-exploration for bleeding did not differ. Thirty-day mortality rates were comparable (TAR group: 3.4% vs. SV group: 4.5%, p = 0.68). Kaplan-Meier analysis until 7 years postoperatively revealed a tendency for improved survival after TAR (75% vs. 62%; log-rank p = 0.12).

CONCLUSION

TAR neither impairs rapid revascularization nor reduces its safety in patients with AMI. It may result in improved long-term outcome and should be preferred in the clinical setting of AMI.

National Trends and Geographic Variation in Bilateral Internal Mammary Artery Use in the United States

BACKGROUND

The goal of this study was to characterize the adoption rate and regional variation in bilateral internal mammary artery (BIMA) use during coronary artery bypass grafting (CABG) in the United States.

METHODS

Observational study of 100% sample of fee-for-service Medicare beneficiaries aged 65 years or older, continuously enrolled in Parts A and B from 2009 to 2014 (n = 162,860,439). Rates of beneficiaries receiving a BIMA versus single internal mammary artery (SIMA) during CABG are expressed per 1,000 beneficiaries and aggregated by Hospital Referral Region (HRR). An HRR is a validated unit for quantifying regional variation in health care.

RESULTS

The absolute national rate of BIMA use declined during the study period from 0.21 claims per 1,000 beneficiaries in 2009 to 0.13 in 2014 (p < 0.001). When indexed to overall CABG volume, no change was seen in the frequency of BIMA use over time (p = 0.883). SIMA use ranged from 1.3 to 8.5 claims per 1,000 Medicare beneficiaries, whereas BIMA use ranged from 0 to 1.5 (p < 0.001). A significant correlation was found between regional volume of SIMA use and likelihood of BIMA use (correlation coefficient 0.673, p < 0.001). Although both SIMA and BIMA use correlated with regional volume of diagnostic cardiac catheterization, the correlation was stronger for SIMA use (correlation coefficient 0.962 versus 0.682, p < 0.001).

CONCLUSIONS

Over the past 5 years, no growth was seen in BIMA use among Medicare beneficiaries, and the frequency of BIMA use during CABG remained low. There was significant regional variation in BIMA use, however, which demonstrates opportunity for continued growth of BIMA grafting.

Association of Internal Mammary Artery Flow with Different Comorbidities and Post-Coronary Artery Bypass Graft Complications

Objective

The internal mammary artery (IMA) is commonly used arterial graft for coronary artery bypass surgery (CABG). The IMA has a better patency and survival. This study considers different comorbidities and conditions where IMA flow may be low. Therefore, the main objective is to determine the flow of IMA in different diseases, its relation to gender, age, and in different blood groups in order to prevent possible complications.

Methods

A prospective study was conducted at the Cardiac Surgery Unit, Civil Hospital Karachi from January 2013 to December 2015. The data of 158 patients who underwent primary, isolated, and CABG surgery was collected. Free flow of IMA was measured immediately after harvesting for 30 seconds within a syringe, and its relationship with different diseases and conditions was examined. Data was collected using a structured questionnaire from the patients' medical record files and it was later analyzed and entered into the Statistical Package for Social Sciences (SPSS) software, V17 (IBM SPSS Statistics, Armonk, NY).

Results

The mean flow was 11.6 ± 9.6 ml. There was no difference in flow related to gender, diabetes, smoking, renal disease, and chronic obstructive pulmonary disease (COPD). There was significantly higher flow in the age group of 50 to 60 years (p = 0.002), hypertensive patients (p = 0.016), patients with liver disease (p = 0.001), BMI > 30 (p = 0.041), and the blood group AB+ (p = 0.02). The atrial fibrillation and readmissions were higher in patients who had low flow. Low flow IMA, which was used on left anterior descending (LAD) artery stenosis patients, showed a significantly higher need of pharmacological and mechanical support.

Conclusion

IMA should be used carefully in patients where its flow is low; conditions must be analyzed where flow may be low to avoid complications. Further studies are warranted.

Management and Prevention of Saphenous Vein Graft Failure: A Review

Coronary artery bypass grafting (CABG) remains a vital treatment for patients with multivessel coronary artery disease (CAD), especially diabetics. The long-term benefit of the internal thoracic artery graft is well established and remains the gold standard for revascularization of severe CAD. It is not always possible to achieve complete revascularization through arterial grafts, necessitating the use of saphenous vein grafts (SVG). Unfortunately, SVGs do not have the same longevity, and their failure is associated with significant adverse cardiac outcomes and mortality. This paper reviews the pathogenesis of SVG failure, highlighting the difference between early, intermediate, and late failure. It also addresses the different surgical techniques that affect the incidence of SVG failure, as well as the medical and percutaneous prevention and treatment options in contemporary practice.

Contemporary use of arterial and venous conduits in coronary artery bypass grafting: anatomical, functional and clinical aspects

Although the benefits of using the left internal mammary artery to bypass the left anterior descending artery (LAD) have been extensively ascertained, freedom from major cardiovascular events and survival after coronary artery bypass grafting (CABG) also correlate with the completeness of revascularisation. Hence, careful selection of the second-best graft conduit is crucial for CABG success. The more widespread use of saphenous vein grafts contrasts with the well-known long-term efficacy of multiple arterial grafting, which struggles to emerge as the procedure of choice due to concerns over increased technical difficulties and higher risk of postoperative complications. Conduit choice is at the discretion of the operator instead of being discussed by the heart team, where cardiologists are not usually engaged in such decisions due to a hypothetical lack of technical knowledge. Furthermore, according to the ESC/EACTS guidelines, traditional CABG remains the gold standard for multi-vessel coronary artery disease with complex LAD stenosis, but hybrid procedures using percutaneous coronary intervention for non-LAD targets could combine the best of two worlds. With the aim of raising the cardiologist's awareness of the surgical treatment options, we provide a comprehensive overview of the anatomical, functional and clinical aspects guiding the decision-making process in CABG strategy.

The future of off-pump coronary artery bypass grafting: a North American perspective

Off-pump coronary artery bypass graft (OPCAB) is currently performed routinely in a minority of specialized centers and in many more centers, utilized only when a porcelain aorta mandates a no-touch aortic technique. The OPCAB literature can be summarized as follows: (I) large-scale randomized trials in relatively low risk patients that include surgeons with a range of experience demonstrating no consistent beneficial differences in major cardiovascular and cerebrovascular outcomes but lower transfusion rates and shorter length of stay, tempered by some reports of higher rates of incomplete revascularization and lower rates of long term graft patency; (II) smaller randomized controlled trials (RCTs) from highly specialized programs demonstrating equivalent or superior outcomes with OPCAB and similar completeness of revascularization and graft patency; and (III) observational data from large databases demonstrating a consistent benefit of OPCAB, especially in higher-risk patient subsets. Our rationale for OPCAB remains that if complete and precise revascularization can be safely and routinely accomplished, then the patient should benefit by avoiding the morbidities that can be attributed to aortic cannulation/clamping, cardiopulmonary bypass (CPB), hemodilution, hypothermia and global myocardial ischemia/cardioplegia. We further believe that OPCAB procedures should emphasize the use of arterial grafts to optimize long term patency and minimize aortic manipulation to limit the risk of stroke. Moving forward, the off-pump surgical community and specialty societies must address the challenge of training surgeons and their teams to master this technically demanding procedure. Furthermore, OPCAB opens the door to minimally-invasive surgical revascularization via hybrid coronary revascularization (HCR). A large NIH-funded RCT is currently underway to determine whether hybrid revascularization can offer a superior alternative to multi-vessel percutaneous coronary intervention for patients with low SYNTAX score and proximal LAD disease.

Coronary artery bypass surgery in diabetic patients - risk factors for sternal wound infections

The incidence of sternal wound infections (SWI) after coronary artery bypass surgery (CABG) as reported worldwide is low. However, it is associated with significant increase of postoperative mortality and treatment costs. The major risk factors discussed are diabetes mellitus and bilateral IMA harvesting of the internal mammary artery. This study analyses data of 590 patients receiving CABG concerning the risk factors for SWI. Sternal wound infections occur significantly more often in diabetic patients, one crucial and significant additional risk factor is obesity.

Total arterial grafting is associated with improved clinical outcomes compared to conventional myocardial revascularization at 10 years follow-up

The use of arterial conduits is associated with incremental benefits when compared to conventional CABG surgery, albeit there is a paucity of data regarding the long-term outcomes of either techniques. Among 973 consecutive patients undergoing CABG, a propensity-match study was performed to compare total arterial revascularization technique (G1) with a conventional approach (LITA on LAD plus additional SVGs, G2). The study population was propensity-matched based on preoperative characteristics (age, sex, risk factors). Mean number of grafted vessels (G1 = 2.39 ± 0.55 vs G2 = 2.37 ± 0.7; p = 0.79) and aortic cross-clamp time (G1 = 36 ± 6 vs G2 = 35 ± 6 min; p = 0.31) were similar while CPB time was significantly longer in Group 2 (G1 = 50 ± 7 vs G2 = 70 ± 8 min; p = 0.03). Hospital mortality (G1 = 0.6 % vs G2 = 1.3 %; p = 0.41) and overall incidence of postoperative complications were also comparable. Cox regression analysis depicted conventional CABG as an independent predictor for MACCEs (HR = 4.53, CI 95 % = 2-10.28; p < 0.001). Median follow-up time was 112 months: actuarial survival free from cardiac death (G1 = 100 % vs G2 = 95 ± 2.1 %; p = 0.046) and MACCEs (G1 = 97.3 ± 1.5 % vs G2 = 79.4 ± 3.8 %; p < 0.001) was significantly improved in patients undergoing total arterial grafting. Total arterial myocardial revascularization is associated with significantly improved outcomes at 10 years follow-up in terms of cardiac-related mortality and overall event-free survival.

Strategies for the coronary surgeon to remain "competitive and co-operative" in the PCI era

BACKGROUND

The advent of percutaneous intervention has made surgical treatment of coronary artery disease less favored by patients though the evidence that supports CABG in certain patient subsets is strong.

METHODS

Literature review was done using Pubmed, Scopus, Google and Google Scholar with MeSH terms-coronary artery bypass grafting, internal mammary artery, drug eluting stent, stroke, myocardial revascularization.

RESULTS

The adoption of evolving techniques like anaortic off pump grafting, bilateral internal mammary artery use, hybrid and minimally invasive coronary revascularization techniques, intra-operative graft assessment, and heart team approach can lead to better outcomes following surgery as is evidenced by recent literature.

CONCLUSIONS

Though the adoptability of the newer strategies may vary between centers a close coalition between coronary surgeons and cardiologists would ensure that the management of coronary artery disease is based on evidence for the benefit of the patient.

Potassium induced contraction of the internal thoracic artery in vitro is time related: the potential consequences in the analysis of the mechanism of the spasm after coronary artery bypass grafting and in the analysis of the results of in vitro studies

The aim of the present study was to examine how, under in vitro conditions, the human left internal thoracic artery (LITA) reacts to contractile agonist:potassium chloride (KCL) as a function of time, as well as to examine whether a change in the LITA reactivity can correlate with the occurrence of the refractory vascular spasm (RVS). Distal segments of LITA obtained from 33 patients aged 38–73, at the time of routine coronary artery surgical revascularization (CABG). Contractile response to 80 mmol K⁺ was recorded under isometric conditions. In 16 (48,5 %) LITA segments, contractile reaction to K⁺ after experiments ranging 1–10 h were registered. No contractile response even after 10 h of incubation was observed in 17 (51.5 %) LITA segments. Between 120 and 300 min after the beginning of the experiment, the reaction was maximum and amounted up to 300 % control reaction, then decreased. First, with respect to in vitro research isolated by LITA rings, while analyzing the results of the research, one should take into consideration the possibility that during the research, the functional state of the tissues changes and in particular its sensitivity to depolarization of the cell membrane. Second, the change in the sensitivity to depolarization of the cell membrane of the smooth muscles’ LITA might be the potential mechanism causing the occurrence of the postoperative spasm after the CABG treatment.

A pilot randomized controlled trial comparing CABG surgery performed with total arterial grafts or without

OBJECTIVE

To date only a few randomized controlled studies have compared grafting strategies in patients with multi-vessel coronary disease. This study represents a pilot RCT designed to test the feasibility of a trial comparing conventional CABG performed with a LIMA-LAD plus saphenous vein grafts (LIMA+SVG) and CABG performed with total arterial grafting (TAG).

METHODS

Consenting patients undergoing non-redo isolated CABG surgery at a single institution were randomized to TAG or LIMA+SVG groups. Exclusion criteria included prior CABG, emergent procedure, concomitant procedure, varicose veins and renal dysfunction. The primary endpoints were: enrolment >20% and completion of CT coronary angiography at 6 months >80%. Statistical investigation was performed on an intention to treat analysis.

RESULTS

Of 421 eligible patients, 60 were enrolled and 2 withdrew (n = 30 in TAG, n = 28 LIMA+SVG) for 14% enrolment rate. Patient characteristics were similar in each group. No patients died in hospital and adverse events such as MI, stroke and deep sternal wound infection were not significantly different between groups. Clinical follow-up was complete in 100% of patients, with 44/58 (76%) undergoing CT coronary angio at 6 months. Graft occlusion occurred in 2 patients in each group for patency rates of 89% (TAG) and 91% (LIMA+SVG).

CONCLUSIONS

We provide evidence that an RCT comparing grafting strategy is possible but also show that achieving recruitment or follow-up CT may be difficult. Given the excellent patency results and little difference between groups, our findings suggest that the sample size required may make it infeasible to compare graft patency at 6 months as a study end-point.

TRIAL REGISTRATION

Randomized Controlled Trial number: ISRCTN80270323 . Few RCT's exist comparing conventional CABG performed with a LIMA-LAD plus saphenous vein grafts (LIMA+SVG) compared to CABG performed with total arterial grafting (TAG). This study is a pilot RCT designed to test the feasibility of such a trial and identify pitfalls.

Contemporary coronary artery bypass grafting

Current evidence clearly demonstrates that coronary artery bypass grafting (CABG) remains the "gold standard" treatment for most patients with multivessel and left main stem disease. This article summarizes the relevant evidence basis demonstrating that CABG, in comparison to stenting, reduces mortality and subsequent myocardial infarction and the need for repeat revascularization. The article also describes the evidence basis to support the use of more arterial grafts during CABG and the current role of off-pump CABG.

Coronary artery bypass graft: why is the saphenous vein prone to intimal hyperplasia?

Proliferation and migration of smooth muscle cells and the resultant intimal hyperplasia cause coronary artery bypass graft failure. Both internal mammary artery and saphenous vein are the most commonly used bypass conduits. Although an internal mammary artery graft is immune to restenosis, a saphenous vein graft is prone to develop restenosis. We found significantly higher activity of phosphatase and tensin homolog (PTEN) in the smooth muscle cells of the internal mammary artery than in the saphenous vein. In this article, we critically review the pathophysiology of vein-graft failure with detailed discussion of the involvement of various factors, including PTEN, matrix metalloproteinases, and tissue inhibitor of metalloproteinases, in uncontrolled proliferation and migration of smooth muscle cells towards the lumen, and invasion of the graft conduit. We identified potential target sites that could be useful in preventing and (or) reversing unwanted consequences following coronary artery bypass graft using saphenous vein.