Single versus bilateral internal thoracic artery grafts with concomitant saphenous vein grafts for multivessel coronary artery bypass grafting: effects on mortality and event-free survival

Percutaneous coronary intervention versus coronary artery by-pass grafting in premature coronary artery disease: What is the evidence? -A narrative review

Coronary artery disease (CAD) remains one of the leading causes of death globally. In the United States of America, in 2016, 19% of all patients under the age of 65 died of cardiovascular disease despite improvements in primary prevention. The premature clinical onset of symptoms in the young population (<60 years) is much more aggressive than in the older population, and the overall long-term prognosis is poor. CAD appears to have a rapidly progressive form in those under the age of 60 due to genetic predisposition, smoking, and substance abuse, however, the ideal management strategy is still yet to be established. The two primary methods of establishing coronary revascularization are percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG). Despite the increasing prevalence of CAD in the young population, they are consistently underrepresented in major randomized clinical trials of each revascularization strategy. Both CABG and PCI are known to have similar survival rates, but PCI is associated with higher repeat revascularization rate. Many argue this may be due to the progressive nature of CAD combined with the vessel patency time required in a patient under 60 with potentially another 20-30 years of life. There is little in literature regarding the outcomes of these various revascularization strategies in populations under 60 years with CAD. This review summarises the current evidence for each revascularisation strategy in patients under the age of 60 and suggests future avenues of research for this unique age group.

The effect of the multiple arterial grafts compared with single arterial graft for coronary artery bypass grafting on sternal wound complications: A meta-analysis

A meta-analysis investigation was executed to measure the influence of multiple arterial grafts (MAGs) compared with single arterial graft (SAG) for coronary artery bypass grafting (CABG) on sternal wound complications (SWCs). A comprehensive literature inspection till February 2023 was applied and 1048 interrelated investigations were reviewed. The seven chosen investigations enclosed 11 201 individuals with CABG in the chosen investigations' starting point, 4870 of them were using MAGs, and 6331 were using SAG. Odds ratio (OR) in addition to 95% confidence intervals (CIs) were utilised to compute the value of the effect of the MAGs compared with SAG for CABG on SWCs by the dichotomous approaches and a fixed or random model. MAGs had significantly higher SWC (OR, 1.38; 95% CI, 1.10-1.73, P = .005) compared with those with SAG in CABG. MAGs had significantly higher SWC compared with those with SAG in CABG. However, care must be exercised when dealing with its values because of the low number of selected investigations for the meta-analysis.

Post-CABG Deep Sternal Wound Infection: A Retrospective Comparative Analysis of Early versus Late Referral to a Plastic Surgery Unit in a Tertiary Care Center

Background  Deep sternal wound infections (DSWI) following median sternotomy are initially treated by the cardiothoracic surgeons and are referred to a plastic surgical unit late in the course of time.

Methods  This is a retrospective review done in a tertiary care teaching institute from January 2005 to June 2018 and the data of 72 patients who had DSWI out of 4,214 patients who underwent median sternotomy for coronary artery bypass grafting (CABG) was collected with respect to the duration between CABG and presentation of DSWI as well as time of referral to a plastic surgery unit. We defined early referral as < or equal to 15 days from presentation and late referral as > 15 days. Both groups were compared with respect to multiple parameters as well as early and late postoperative course, postoperative complications, and mortality.

Results  The early group had 33 patients, while the late group had 39 patients. The number of procedures done by the cardiothoracic team before referral to the plastic surgery unit is significant ( p = 0.002). The average duration from the presentation of DSWI to definitive surgery was found to be 16.58 days in the early group and 89.36 days in the late group. The rest of the variables that were compared in both the groups did not have significant differences.

Conclusion  There is no statistical difference between early and late referral to plastic surgery in terms of mortality and morbidity. Yet, early referrals could lead to highly significant reduction in total duration of hospital stay, wound healing, and costs. Early referral of post-CABG DSWIs to Plastic surgeons by the cardiothoracic surgeons is highly recommended.

Robustness of the Comparative Observational Evidence Supporting Class I and II Cardiac Surgery Procedures

Background

Current cardiac surgery guidelines give Class I and II recommendations to valve‐sparing root replacement over the Bentall procedure, mitral valve (MV) repair over replacement, and multiple arterial grafting with bilateral internal thoracic artery based on observational evidence. We evaluated the robustness of the observational studies supporting these recommendations using the E value, an index of unmeasured confounding.

Methods and Results

Observational studies cited in the guidelines and in the 3 largest meta‐analyses comparing the procedures were evaluated for statistically significant effect measures. Two E values were calculated: 1 for the effect‐size estimate and 1 for the lower limit of the 95% CI. Thirty‐one observational studies were identified, and E values were computed for 75 effect estimates. The observed effect estimates for improved clinical outcomes with valve‐sparing root replacement versus the Bentall procedure, MV repair versus replacement, and grafting with bilateral internal thoracic artery versus single internal thoracic artery could be explained by an unmeasured confounder that was associated with both the treatment and outcome by a risk ratio of more than 16.77, 4.32, and 3.14, respectively. For MV repair versus replacement and grafting with bilateral internal thoracic artery versus single internal thoracic artery, the average E values were lower than the effect sizes of the other measured confounders in 33.3% and 60.9% of the studies, respectively. For valve‐sparing root replacement versus the Bentall procedure, no study reported effect sizes for associations of other covariates with outcomes.

Conclusions

The E values for observational evidence supporting the use of valve‐sparing root replacement, MV repair, and grafting with bilateral internal thoracic artery over the Bentall procedure, MV replacement, and grafting with single internal thoracic artery are relatively low. This suggests that small‐to‐moderate unmeasured confounding could explain most of the observed associations for these procedures.

Bilateral internal thoracic artery grafting: propensity analysis of the left internal thoracic artery versus the right internal thoracic artery as a bypass graft to the left anterior descending artery

OBJECTIVES

To compare different configurations of the bilateral internal thoracic arteries for the left coronary system and examine early and late outcomes, including mid-term graft patency.

METHODS

We reviewed 877 patients who underwent primary isolated coronary artery bypass grafting using in situ bilateral internal thoracic arteries [in situ right internal thoracic artery (RITA)-to-left anterior descending artery (LAD) grafting, n = 683; in situ left internal thoracic artery (LITA)-to-LAD grafting, n = 194]. We compared mid-term patency between the grafts. Propensity score matching was performed to investigate early and long-term outcomes.

RESULTS

The 2-year patency rate for RITA-to-LAD and LITA-to-LAD grafts were similar. Multivariate analysis revealed that RITA-to-non-LAD anastomosis (P = 0.029), postoperative length of stay (P = 0.003) and chronic obstructive pulmonary disease (P = 0.005) were associated with graft failure. After statistical adjustment, 176 propensity-matched pairs were available for comparison. RITA-to-LAD grafting enabled a more distal anastomosis. Kaplan-Meier analysis revealed that the incidences of death, repeat revascularization and myocardial infarction were significantly higher in the LITA-to-LAD group among both the unmatched and matched samples (P = 0.045 and 0.029, respectively).

CONCLUSIONS

The mid-term patency and outcomes of RITA-to-LAD grafting are good and reduces future cardiac event, in contrast to LITA-to-LAD grafting.

Radial Artery Versus Right Internal Thoracic Artery Versus Saphenous Vein as the Second Conduit for Coronary Artery Bypass Surgery: A Network Meta-Analysis of Clinical Outcomes

Background

There remains uncertainty regarding the second‐best conduit after the internal thoracic artery in coronary artery bypass grafting. Few studies directly compared the clinical results of the radial artery (RA), right internal thoracic artery (RITA), and saphenous vein (SV). No network meta‐analysis has compared these 3 strategies.

Methods and Results

MEDLINE and EMBASE were searched for adjusted observational studies and randomized controlled trials comparing the RA, SV, and/or RITA as the second conduit for coronary artery bypass grafting. The primary end point was all‐cause long‐term mortality. Secondary end points were operative mortality, perioperative stroke, perioperative myocardial infarction, and deep sternal wound infection (DSWI). Pairwise and network meta‐analyses were performed. A total of 149 902 patients (4 randomized, 31 observational studies) were included (RA, 16 201, SV, 112 018, RITA, 21 683). At NMA, the use of SV was associated with higher long‐term mortality compared with the RA (incidence rate ratio, 1.23; 95% CI, 1.12–1.34) and RITA (incidence rate ratio, 1.26; 95% CI, 1.17–1.35). The risk of DSWI for SV was similar to RA but lower than RITA (odds ratio, 0.71; 95% CI, 0.55–0.91). There were no differences for any outcome between RITA and RA, although DSWI trended higher with RITA (odds ratio, 1.39; 95% CI, 0.92–2.1). The risk of DSWI in bilateral internal thoracic artery studies was higher when the skeletonization technique was not used.

Conclusions

The use of the RA or the RITA is associated with a similar and statistically significant long‐term clinical benefit compared with the SV. There are no differences in operative risk or complications between the 2 arterial conduits, but DSWI remains a concern with bilateral ITA when skeletonization is not used.

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.

Bilateral internal thoracic arteries: what is the State of the ART?

PURPOSE OF REVIEW

To provide a broad overview of the current state of knowledge of coronary artery bypass grafting with bilateral internal thoracic artery (BITA).

RECENT FINDINGS

There exists a large body of literature from mostly observational studies supporting the use of BITA in patients undergoing coronary artery bypass grafting but selection bias is a major issue with nonrandomized data. The precise method of BITA use does not appear to impact graft patency nor clinical outcomes - in other words, BITA in any configuration appears to be protective. The major downside is the increased risk of sternal complications, which can be mitigated with sternal-sparring adjuncts. The 5-year interim results of the landmark Arterial Revascularization Trial comparing BITA versus single internal thoracic artery did not show a clinical benefit for BITA but the end-of-trial results are pending. Despite wide guideline support for BITA use, uptake in the surgical community remains low and this is likely because of technical and institutional barriers.

SUMMARY

The published literature thus far supports surgical revascularization with BITA and we eagerly await the 10-year Arterial Revascularization Trial results. The general consensus is that a greater proportion of surgical revascularization should be performed using BITA.

Use Rate and Outcome in Bilateral Internal Thoracic Artery Grafting: Insights From a Systematic Review and Meta-Analysis

Background

This meta‐analysis was designed to assess whether center experience affects the short‐ and long‐term results and the relative benefits of bilateral internal thoracic artery grafting (BITA) for coronary artery bypass grafting.

Methods and Results

MEDLINE and EMBASE were searched to identify all articles reporting the outcome of BITA in patients undergoing coronary artery bypass grafting. The BITA center experience was gauged according to the percentage use of BITA in the institutional overall coronary artery bypass grafting population (%BITA). The primary outcome was long‐term all‐cause mortality. Secondary outcomes were operative mortality, perioperative myocardial infarction, perioperative stroke, deep sternal wound infections (DSWIs), and major postoperative adverse event. The rates of the primary and secondary outcomes were calculated after adjusting for %BITA. Primary and secondary outcomes were also compared between the BITA and the single internal thoracic artery arms in the adjusted studies. Meta‐regression was used to evaluate the effect of %BITA on the primary and secondary outcomes. Thirty‐four studies (27 894 patients undergoing BITA) were included. In the pooled analysis, the incidence rate for long‐term mortality was 2.83% (95% confidence interval, 2.21%–3.61%). %BITA was significantly and inversely associated with long‐term mortality and the rate of DSWI. In the pairwise comparison, %BITA was significantly and inversely associated with the risk of long‐term mortality and DSWI in the group undergoing BITA.

Conclusions

BITA series with higher %BITA report significantly lower long‐term mortality and DSWI rate as well as higher long‐term survival advantage and lower relative risk of DSWI in their BITA cohort. These findings suggest that a specific volume‐outcome relationship exists for BITA grafting.

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.

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.

Bilateral Internal Mammary Artery Use Can Be Safely Taught Without Increasing Morbidity or Mortality

BACKGROUND

Evidence shows a likely survival benefit with the use of bilateral internal mammary arteries (BIMA) compared with a single internal mammary artery (SIMA). Nonetheless, BIMA use is often not used or taught because of a perceived increase in operative time and complexity. This study aimed to evaluate operative time, morbidity, and mortality in both resident and nonresident cases using BIMA compared with SIMA.

METHODS

Consecutive patients undergoing isolated coronary artery bypass grafting (October 2012 to April 2015) at a single institution were reviewed. Cases were stratified on the basis of the use of SIMA versus BIMA and resident teaching versus nonresident teaching cases. Primary outcomes included operative time, postoperative morbidity, and mortality.

RESULTS

A total of 416 patients were identified; 335 of 416 (81%) patients received a SIMA, and 81 of 416 (19%) patients received BIMA. A total of 184 of 416 (44%) were resident cases: 143 of the 335 (43%) SIMA cases and 41 of the 81 (51%) BIMA cases. Use of BIMA in resident cases was associated with a longer operative and cardiopulmonary bypass (CPB) time than resident SIMA cases, but this increased time did not affect morbidity or mortality. Use of SIMA versus BIMA in nonresident cases had no significant difference on total operative time, CPB time, postoperative morbidity, or mortality. Overall, operative and 1-year mortality rates were similar in the SIMA and BIMA groups (SIMA: 1.2%, 1.8%, respectively; BIMA: 0%, 0%, respectively; p = NS).

CONCLUSIONS

In the hands of an experienced surgeon, BIMA use can be effectively performed without an increase in operative or CPB time. In resident teaching cases, BIMA use may increase operative time, but it can be safely taught without affecting morbidity or mortality.

The Surgical Treatment of Coronary Artery Occlusive Disease: Modern Treatment Strategies for an Age Old Problem

Coronary artery disease remains a formidable challenge to clinicians. Percutaneous interventions and surgical techniques for myocardial revascularization continue to improve. Concurrently, in light of emerging data, multiple practice guidelines have been published guiding clinicians in their therapeutic decisions. The multidisciplinary Heart Team concept needs to be embraced by all cardiovascular providers to optimize patient outcomes.

A systematic review and meta-analysis of in situ versus composite bilateral internal thoracic artery grafting

OBJECTIVES

This meta-analysis examines whether there is any advantage of coronary artery bypass graft with bilateral internal thoracic artery (BITA) as an in situ versus composite graft.

METHODS

We searched MEDLINE and EMBASE Databases from 1996 to 2016 for studies that compared coronary artery bypass graft with BITA as in situ versus composite graft. Data were extracted by 2 independent investigators and meta-analyzed with the use of random effects.

RESULTS

Two randomized controlled trials (RCTs; n = 705), 2 matched (n = 1688), and 4 unadjusted observational studies (n = 3517) met inclusion criteria. Composite grafting trended towards greater distal anastomoses (+0.22, 95% confidence interval, -0.01 to +0.45 anastomoses/patient; P = .06 [4 unadjusted observational studies]) and greater distal anastomoses using an internal thoracic artery (+0.80, 95% confidence interval, 0.41-1.18 anastomoses/patient; P < .001 [1 RCT]). There were no differences in perioperative or longer-term composite cardiovascular outcomes comparing in situ versus composite BITA or individual outcomes of mortality, repeat revascularization, myocardial infarction, and cardiovascular mortality. Pooled results differed by study type with pooled results from lower-risk-of-bias RCTs typically showing increases in events rates, and pooled results from higher-risk-of-bias unadjusted observational studies typically showing decreases in event rates of in situ versus composite BITA. Post hoc subgroup analysis suggested possible improvements in all-cause mortality and revascularization for in situ BITA in studies with short-term (<5 years) versus longer-term follow-up, regardless of study type.

CONCLUSIONS

Our meta-analysis found that use of BITA as a composite graft configuration facilitated greater internal thoracic artery revascularization but both grafting strategies offer similar clinical outcomes. Our study supports the use of in situ and composite BITA for select patients but high-quality, long-term prospective trials are needed.

Pure Bilateral Internal Thoracic Artery Grafting in Diabetic Patients With Triple-Vessel Disease

BACKGROUND

Despite the documented superior long-term patency of bilateral internal thoracic artery (BITA) grafting, use of BITAs remains low, especially in diabetic patients. We analyzed the results of pure BITA grafting to determine whether the potential survival advantage outweighs the risk of wound infection in diabetic patients.

METHODS

We performed a retrospective analysis of 791 consecutive patients (389 diabetic, 402 nondiabetic) with triple-vessel disease who underwent off-pump coronary artery bypass using only skeletonized BITAs from 2001 to 2010. We used propensity score matching to match 315 nondiabetic patients with diabetic patients.

RESULTS

The groups did not differ significantly regarding 10-year survival (diabetic, 84.2% ± 4.5%; nondiabetic, 80.8% ± 4.7%; p = 0.828) or freedom from major adverse cardiovascular events (diabetic, 73.5% ± 5.2%; nondiabetic, 71.8% ± 5.3%; p = 0.431). Diabetes was not predictive of deep sternal infection (odds ratio, 1.11; 95% confidence interval, 0.23 to 5.31; p = 0.895). Results of stratified competing risks regression analysis showed that the risk of target vessel revascularization in diabetic patients was similar to that of nondiabetic patients (subdistribution hazard ratio, 0.67; 95% confidence interval, 0.16 to 2.80; p = 0.585).

CONCLUSIONS

Off-pump coronary artery bypass grafting using pure BITAs produced excellent clinical outcomes in both diabetic and nondiabetic patients. This strategy did not increase the incidence of deep sternal infection in diabetic patients. We recommend BITA grafting, which has proven long-term patency, as a strategy of choice in diabetic patients.

Predictors of immediate and long-term outcomes of coronary bypass surgery in patients with left ventricular dysfunction

Despite encouraging improvements, outcomes of coronary artery bypass grafting (CABG) in the presence of left ventricular (LV) dysfunction remain poor. In the present study, the authors' experience on this subject was reviewed to establish the predictors of immediate and long-term results of surgery. Out of 4383 consecutive patients with multivessel coronary artery disease who underwent primary isolated CABG at the authors' institution from January 1999 throughout September 2014, 300 patients (mean age 66.1 ± 9.6 years) suffered preoperatively from LV dysfunction (defined as LV ejection fraction ≤35 %). The mean expected operative risk (EuroSCORE II) was 10.3 ± 13 %. Hospital deaths and perioperative complications were analyzed retrospectively. Outcomes were evaluated during a mean follow-up of 6.2 ± 4 years. None, one or both internal thoracic arteries (ITAs) were used in 6.3, 29 and 64.7 % of cases, respectively. There were 16 (5.3 %) hospital deaths. Prolonged invasive ventilation (17.7 %), acute kidney injury (14.7 %) and multiple blood transfusion (21.3 %) were the most frequent major postoperative complications. The 10-year non-parametric estimates of freedom from all-cause death, cardiac death, and major adverse cardiac and cerebrovascular events (MACCEs) were 47.8 [95 % confidence interval (CI) 44.1-51.5], 65.3 (95 % CI 61.4-69.2), and 42.3 % (95 % CI 38.3-46.3), respectively. Shared predictors of decreased late survival and MACCEs were old age (P < 0.04), chronic lung disease (P < 0.01), chronic dialysis (P < 0.0001) and extracardiac arteriopathy (P < 0.045). After adjustment for corresponding risk factors, freedom from cardiac death was higher when both ITAs were used but only for patients with significant increase of LV ejection fraction early after surgery (P = 0.04). In patients with LV dysfunction, CABG may be performed with acceptable hospital mortality and long-term survival. Late outcomes depend mainly on preoperative characteristics of the patients. The use of both ITAs for myocardial revascularization may give long-term survival benefits but only for patients whose LV function improves significantly early after surgery.

Bilateral Internal Mammary Artery Use for Coronary Artery Bypass Grafting Remains Underutilized: A Propensity-Matched Multi-Institution Analysis

BACKGROUND

Bilateral internal mammary arterial (BIMA) grafts have repeatedly demonstrated superior outcomes compared with single IMA (SIMA) after coronary artery bypass grafting (CABG). Despite known survival benefits with BIMA use, perceived perioperative challenges often preclude BIMA use. We hypothesized that the use of BIMA remains underutilized, even in low-risk patients.

METHODS

A total of 43,823 primary, isolated CABG patients in a regional Society of Thoracic Surgeons Database were evaluated. Patients were stratified by BIMA versus SIMA use. Surgical candidates considered "low risk" for BIMA use included the following: age less than 70 years; no or mild chronic lung disease; body mass index less than 30; and absence of diabetes. The BIMA patients (n = 1,333) were 1:1 propensity matched to SIMA patients (n = 1,333) and outcomes were compared.

RESULTS

Overall, BIMA use was 3%; 24% (n = 10,327) of patients met "low-risk" criteria for BIMA use. Among "low-risk" patients, BIMA utilization was 6%. Propensity-matched comparisons revealed similar preoperative risk profiles between BIMA and SIMA patients (Predicted Risk of Mortality [PROM] 1.1% vs 1.1%, p > 0.05). The BIMA use was associated with longer cross-clamp time (71 vs 62 minutes, p < 0.05). Importantly, BIMA use was not associated with increased postoperative mortality, morbidity, or hospital length of stay (all p > 0.05). However, hospital readmission within 30 days was 41% greater for BIMA patients compared with SIMA patients (p = 0.01).

CONCLUSIONS

Bilateral IMA graft use appears to remain underutilized in the modern surgical era, even in low surgical risk patients. The BIMA use does not appear to increase the risk of postoperative morbidity, although requires longer operative times and a higher risk for readmission. Efforts to more clearly understand surgeon motivators for the use of BIMA grafting are needed.

The impact of a second arterial graft on 5-year outcomes after coronary artery bypass grafting in the Synergy Between Percutaneous Coronary Intervention With TAXUS and Cardiac Surgery Trial and Registry

OBJECTIVE

Despite various evidence supporting the advantages of multiple arterial grafting, inconsistencies in use of the procedure have resulted in high variability in the acceptance and practice of arterial grafting. The purpose of this study was to assess the effects of an arterial versus venous second grafts on outcomes at 5-year follow-up in the coronary artery bypass grafting population from the Synergy Between Percutaneous Coronary Intervention With TAXUS and Cardiac Surgery (SYNTAX) trial.

METHODS

Patients (n = 1419) with an arterial graft to the left anterior descending artery and ≥1 other graft were included and divided according to the second graft's type: 2nd-graft-arterial group (n = 456) and 2nd-graft-venous group (n = 963). Five-year outcomes were compared between subgroups. Event rates were estimated with Kaplan-Meier analyses. Propensity-score matching was used, to control for selection bias due to nonrandom group assignment in a 1:1 manner, resulting in 432 pairs with balanced baseline characteristics.

RESULTS

In unmatched groups, the 2nd-graft-arterial group had significantly lower rates of death (8.9% vs 13.1%; P = .02), and composite safety endpoint of death/stroke/myocardial infarction (13.3% vs 18.7%; P = .02), compared with the 2nd-graft-venous group. The rate of major adverse cardiac or cerebrovascular events was similar between groups (22.9% vs 25.5%; P = .30), because it includes the rate of repeat revascularization (12.6% in the 2nd-graft-arterial group vs 9.6% in the 2nd-graft-venous group; P = .10). After propensity-score matching, no statistically significant differences were found between groups.

CONCLUSIONS

This study reveals comparable 5-year outcomes with arterial and venous conduits as second grafts after an arterial graft anastomosed to the left anterior descending artery. This study demonstrates the multi-institutional variation in patient selection and operator technique with regard to arterial revascularization, although extended follow-up beyond 5 years is required to estimate its impact on long-term outcomes.

CLINICAL TRIAL NUMBER

NCT00114972.

Continuous postoperative insulin infusion reduces deep sternal wound infection in patients with diabetes undergoing coronary artery bypass grafting using bilateral internal mammary artery grafts: a propensity-matched analysis

OBJECTIVES

Deep sternal wound infection (DSWI), especially in patients with diabetes mellitus (DM), is a major concern after coronary artery bypass grafting (CABG) with bilateral internal mammary artery (BIMA) grafts. We evaluated the risk of DSWI and other clinical outcomes between continuous insulin infusion therapy (CIT) and insulin sliding scale therapy (IST) in a cohort of DM patients who underwent CABG with BIMA.

METHODS

The clinical records of DM patients who underwent isolated CABG with BIMA were retrospectively reviewed. The study population consisted of 95 patients who received CIT and 126 patients who received IST. Furthermore, a one-to-one matched analysis based on estimated propensity scores for patients who received CIT or IST yielded two groups comprising 58 patients each. The proportion of patients with DSWI, overall survival rates and major adverse cardiac events were compared between the two groups in the overall and the propensity-matching cohort.

RESULTS

The prevalence of DSWI requiring debridement and closure was significantly reduced in the CIT group compared with that in the IST group [1/95 (1.1%) vs 9/126 (7.1%), P = 0.031]; these results were not attenuated even after propensity-matching analysis [0/58 (0%) vs 6/58 (10.3%), P = 0.031]. The mean preoperative glucose levels were similar between the two groups (157.5 ± 54.6 vs 176.1 ± ±70 mg/dl, P = 0.063), whereas the mean glucose values were significantly lower on the first and second operative days in the CIT group than in the IST group (132.9 ± 44.1 vs 197.8 ± 78.6 mg/dl, P < 0.0001; 153.5 ± 58.8 vs 199.6 ± 89.1 mg/dl, P < 0.0001, respectively). The glucose variability levels within 24 h postoperatively were significantly higher in the IST group (46.1 ± 19.4 vs 66.4 ± 26.8 mg/dl, P < 0.0001). The 30-day and 1-year survival rates were similar between the two groups (100 vs 99.2%, P = 0.384; 96.6 vs 94.4%, P = 0.454). No results were changed in the propensity-matching models.

CONCLUSIONS

The CIT approach reduced the variability in glucose concentration and resulted in fewer instances of DSWI after CABG with BIMA grafts.

Bilateral internal mammary artery grafting: rationale and evidence

Coronary artery bypass graft (CABG) surgery remains the preferred mode of revascularization in patients with complex multi-vessel coronary artery disease. The left internal mammary artery (IMA) and saphenous vein are the most commonly utilized conduits in CABG surgery and are still considered to be the gold standard by most surgeons. However, there is emerging evidence that use of bilateral IMAs is associated with significantly better long-term outcomes and the benefit increases with time from surgery. In spite of this incremental beneficiary effect, most surgeons are reluctant to use both IMAs, because it is technically more demanding, time-consuming and is associated with marginally higher sternal wound infection rates. This review highlights the histological features, physiological characteristics and genomics of IMAs that provide the basis for the use of these vessels during CABG surgery. Additionally, the superiority of the bilateral IMAs with regard to patency and long-term outcomes is also discussed in detail. Furthermore, the safety of using bilateral IMAs with regard to early postoperative outcomes with special reference to deep sternal wound infections has been addressed. The present review provides enough evidence to convince more surgeons about the advantages of bilateral IMA grafting.

Bilateral internal mammary artery grafting in obese: outcomes, concerns and controversies

Obese patients are generally considered unsuitable to receive bilateral internal mammary arteries (BIMA) during coronary artery bypass grafting (CABG) due to the perceived vulnerability to sternal wound infection and lack of evidence supporting long-term survival benefit. However, no consistent evidence currently discourages the use of BIMA in obese patients. The present review questions the common perception that obesity unacceptably increases the risk of sternal wound complications in patients receiving BIMA grafting. Moreover, the use of skeletonization harvesting technique is expected to further minimize such a risk. Our institutional experience confirmed that BIMA grafting is a safe strategy which does not increase operative mortality and does not significantly affect the incidence of sternal wound complications. On the other hand, a long term benefit in terms of overall survival and freedom from repeat revascularization from the use of BIMA was found.

Right internal mammary artery versus radial artery as second arterial conduit in coronary artery bypass grafting: a case-control study of 1526 patients

OBJECTIVE

Additional arterial grafts such as the right internal mammary artery (RIMA) or the radial artery (RA) have been proposed to improve long term outcomes in coronary artery bypass grafting (CABG). RA is largely preferred over RIMA as it is less technically demanding and there is a perception that bilateral IMA usage increases the risk of sternal wound complications. However, there is a paucity of direct comparison of the two conduits to guide surgeons to choose the best second arterial conduit for CABG.

METHODS

A propensity score adjusted analysis of patients undergoing multiple arterial grafting with RIMA (n = 747) and RA (n = 779) during the study period (2001-2013) was conducted to investigate the impact of the two strategies on early and late outcomes.

RESULTS

RIMA did not increase the incidence of postoperative complications including deep sternal wound infection (P = 0.8). Compared to the RIMA, the RA was associated with an increased risk for late mortality (Hazard Ratio [HR] 1.9; 95% confidence interval (CI) 1.2-3.1; P = 0.008) and repeat revascularization (HR 1.5; 95% CI 1.0-2.2; P = 0.044). A trend towards an extra risk for late mortality from RA over RIMA was observed among diabetic (HR 3.3; 95% CI 1.1-9.7) and obese patients (HR 2.1; 95% CI 0.8-5.46).

CONCLUSIONS

RIMA as a second conduit did not increase the operative risk including sternal wound complications and improved long term outcomes including overall survival when compared to RA. This advantage was stronger among diabetic and obese patients. These findings strongly support RIMA as the first choice second arterial conduit in CABG. Further randomized studies with angiographic control and long-term follow-up are needed to address this issue.

Effect of Bilateral Internal Mammary Artery Grafts on Long-Term Survival

Background—

Although the potential survival benefit of bilateral internal mammary artery (BIMA) grafting in comparison with single internal mammary artery (SIMA) grafting has been emphasized by many investigators, the use of BIMA is still low in clinical practice in the absence of randomized trials and long-term results. In the current study, we aimed to assess if there is a long-term survival benefit of BIMA up to 10 years after coronary bypass surgery.

Methods and Results—

We selected published articles comparing survival between SIMA and BIMA patients with follow-up duration of more than a mean of 9 years. We evaluated the log hazard ratio with 95% confidence interval for included studies by using a random-effects meta-analysis. Nine eligible observational studies provided 15 583 patients (8270 SIMA and 7313 BIMA) for meta-analysis. Five studies used propensity score methods for statistical adjustment, 2 with a propensity score–based patient-matching method and 3 with quintile-based stratification. A significant reduction in mortality by using BIMA was observed (hazard ratio, 0.79; 95% confidence interval, 0.75–0.84); no study showed any significantly harmful effect of BIMA on survival. Subgroups of studies using different statistical approaches—unmatched, quintile-based propensity score analysis, and propensity score–based exact patient matching—all showed the survival benefit of BIMA grafting.

Conclusions—

BIMA grafting appears to have better survival with up to 10 years follow-up in comparison with SIMA grafting. Long-term survival benefit of BIMA seems to continue in the second decade after surgery. An ongoing randomized trial comparing SIMA and BIMA groups will add evidence on this issue.

Radial artery as graft for coronary artery bypass surgery: Advantages and disadvantages for its usage focused on structural and biological characteristics

Radial artery (RA) is the most popular arterial graft after the left internal thoracic artery in both low- and high-risk patients undergoing coronary artery bypass grafting. Various arterial grafts such as the right internal thoracic artery, the right gastroepiploic artery, and the inferior epigastric artery have also gained ground over the past 30 years because of the intimal hyperplasia and atherosclerosis of the saphenous vein leading to late graft occlusion. In this review article we would like to present the utility of the RA as a graft, focused mainly on its structural and biological characteristics.

Bilateral versus single internal mammary coronary artery bypass grafting in Sweden from 1997-2008

BACKGROUND

Prior observational studies have suggested better outcomes in patients who receive bilateral internal mammary arteries (BIMA) during coronary artery bypass grafting (CABG) compared with patients who receive a single internal mammary artery (SIMA). The aim of this study was to analyze the association between BIMA use and long-term survival in patients who underwent primary isolated CABG.

METHODS AND RESULTS

Patients who underwent primary isolated non-emergent CABG in Sweden between 1997 and 2008 were identified. The SWEDEHEART registry and other national Swedish registers were used to acquire information about patient characteristics and outcomes. Unadjusted and multivariable adjusted regression models were used to estimate the association between BIMA use and early mortality, long-term survival, and a composite of death from any cause or rehospitalization for myocardial infarction, heart failure, or stroke in the overall cohort and in a propensity score-matched cohort. The study population consisted of 49702 patients who underwent CABG with at least one internal mammary artery, and 559 (1%) of those had BIMA grafting. In the adjusted analyses, BIMA use was not associated with better survival compared with SIMA use in the overall cohort (hazard ratio (HR) for death: 1.16, 95% confidence interval (CI): 0.97 to 1.37) or in the matched cohort (HR: 1.04, 95% CI: 0.78 to 1.40). The results were similar for early mortality and the composite endpoint. Reoperation for sternal wound complications was more common among BIMA patients (odds ratio: 1.71, 95% CI: 1.01 to 2.88).

CONCLUSIONS

BIMA grafting was performed infrequently and was not associated with better outcomes compared with SIMA grafting in patients undergoing non-emergent primary isolated CABG in Sweden during 1997-2008.

Bilateral internal mammary artery grafting

The superiority of the left internal mammary artery over the saphenous vein graft led many surgeons to adopt bilateral internal mammary artery (BIMA) as a good surgical option for further improving late outcome of patients undergoing myocardial revascularization. However, routine use of BIMA was limited by some potential drawbacks: the increase of deep sternal wound problems, especially in diabetic patients; the shortness of right internal mammary artery (RIMA), which limited its utilization as an in situ graft; the low patency rate if grafted to the right coronary artery; and the longer operative time. The skeletonization of the internal mammary artery along with a better glucose control in diabetic patients significantly reduced the incidence of deep sternal problems. Another problem to solve was finding the optimal target of the RIMA. The general consensus is that RIMA appears to be more efficient if grafted to the lateral wall. The Y or T configuration of double mammary arteries could be more helpful to reach the lateral target vessels. Finally, recent reports clearly demonstrate the superiority of BIMA over single internal mammary artery in terms of survival or quality of life. The latter finding has also been reported in diabetic patients.

Current status of arterial grafts for coronary artery bypass grafting

For over a decade there has been accumulating evidence that the use of more than a single arterial graft during coronary artery bypass grafting can improve clinical outcomes. However the vast majority of patients in most developed countries still only receive a single arterial conduit even in the presence of multivessel coronary artery disease. This review summarizes the current evidence for the use of a second internal mammary artery and/or radial artery graft. While in comparison to vein grafts the superior patency of internal mammary artery grafts is well established, there now exists strong and consistent evidence of the superior patency of radial arteries over the longer term. Likewise, there is a rapidly growing body of evidence that the superior patency of both these arteries in comparison to vein grafts translates into improved clinical outcomes.

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

BACKGROUND

Increasing evidence continues to demonstrate a survival advantage for bilateral internal mammary artery (BIMA) over left internal mammary artery (LIMA) for coronary artery bypass grafting (CABG). We performed an updated meta-analysis of published studies comparing BIMA versus LIMA in CABG operations and assessed differences in long-term survival.

METHODS

Electronic searches for studies comparing BIMA versus LIMA were performed using three databases from 1972 to December 2012. Studies with at least four years of follow-up and at least 100 patients in each group were included for review. We used a random-effect model and pooled hazard ratios from across all included studies.

RESULTS

No randomized controlled trials and 27 observational studies totaling 79,063 patients (19,277 BIMA, 59,786 LIMA) were included for final analysis. The BIMA group demonstrated significantly better long-term survival than the LIMA group [hazard ratio, 0.78; confidence interval, 0.72-0.84; P<0.00001].

CONCLUSIONS

In an updated meta-analysis, we demonstrate an increase in long-term survival in patients receiving BIMA as a primary grafting strategy over those receiving a LIMA. Although no randomized controlled trials were included in this meta-analysis, the survival benefit seen with a BIMA cannot be overlooked when determining which operation to perform in CABG patients. Until the long-term results of the ART trial are published, we offer best available evidence in favor of BIMA over LIMA for CABG surgery.

Is there any further advantage of using more than one internal mammary artery? Literature review and analysis

The use of the internal mammary artery reduces the incidence of late adverse effects and improves survival after coronary artery bypass grafting. Therefore, internal mammary artery grafts ought to be used in all patients undergoing coronary artery bypass grafting (level II evidence), although in the UK, only 95% of the patients receive an internal mammary artery graft. This is due to factors such as poor left ventricular function, old age, previous radiation to the thoracic cavity, or emergency surgery. As there are biological similarities between the left and right internal mammary artery, one can extrapolate that the use of 2 internal mammary artery grafts may provide additional benefits. Bilateral internal mammary artery grafting can be safely performed in most patients (level II evidence). The late survival in patients with bilateral internal mammary artery grafts is favorable. However, there is as yet no completed randomized trial on this subject. Thus the lack of robust data makes previous reports amenable to criticism. This review examines published data on bilateral internal mammary artery revascularization spanning the last 15 years, and addresses the advantages and disadvantages of arterial conduits in coronary surgery.

Autologous microsurgical breast reconstruction and coronary artery bypass grafting: an anatomical study and clinical implications

OBJECTIVE

To identify possible avenues of sparing the internal mammary artery (IMA) for coronary artery bypass grafting (CABG) in women undergoing autologous breast reconstruction with deep inferior epigastric artery perforator (DIEP) flaps.

BACKGROUND

Optimal autologous reconstruction of the breast and coronary artery bypass grafting (CABG) are often mutually exclusive as they both require utilisation of the IMA as the preferred arterial conduit. Given the prevalence of both breast cancer and coronary artery disease, this is an important issue for women's health as women with DIEP flap reconstructions and women at increased risk of developing coronary artery disease are potentially restricted from receiving this reconstructive option should the other condition arise.

METHODS

The largest clinical and cadaveric anatomical study (n=315) to date was performed, investigating four solutions to this predicament by correlating the precise requirements of breast reconstruction and CABG against the anatomical features of the in situ IMAs. This information was supplemented by a thorough literature review.

RESULTS

Minimum lengths of the left and right IMA needed for grafting to the left-anterior descending artery are 160.08 and 177.80 mm, respectively. Based on anatomical findings, the suitable options for anastomosis to each intercostals space are offered. In addition, 87-91% of patients have IMA perforator vessels to which DIEP flaps can be anastomosed in the first- and second-intercostal spaces.

CONCLUSION

We outline five methods of preserving the IMA for future CABG: (1) lowering the level of DIEP flaps to the fourth- and fifth-intercostals spaces, (2) using the DIEP pedicle as an intermediary for CABG, (3) using IMA perforators to spare the IMA proper, (4) using and end-to-side anastomosis between the DIEP pedicle and IMA and (5) anastomosis of DIEP flaps using retrograde flow from the distal IMA. With careful patient selection, we hypothesize using the IMA for autologous breast reconstruction need not be an absolute contraindication for future CABG.

Propensity matched analysis of bilateral internal mammary artery versus single left internal mammary artery grafting at 17-year follow-up: validation of a contemporary surgical experience

OBJECTIVES

Bilateral internal mammary arteries (BIMA) remains widely underutilized in coronary artery bypass grafting (CABG). Although prior research has demonstrated a long-term benefit of the use of BIMA over left internal mammary artery (LIMA)-only, validation of these results is lacking in a contemporary surgical experience. We compared complications and survival at 17-year follow-up in a large series of consecutive CABG patients from a single institution that underwent BIMA grafting with a propensity-matched group where LIMA only was used.

METHODS

Propensity scores representing the estimated probabilities of patients receiving either BIMA or LIMA alone were developed based on 22 observed baseline covariates in a logistic regression model with procedure group as the dependent variable. The nearest-neighbour-matching algorithm with Greedy 5-1 Digit Matching was used to produce two patient cohorts of 928 patients each balanced for baseline factors. We compared 30-day morbidity and mortality, as well as long-term survival at 5-year intervals up to 17-year follow-up.

RESULTS

In-hospital and 30-day mortality was 0.8% for the BIMA group and 1.1% for the LIMA-saphenous vein grafting (SVG). No significant difference was found in complications, mortality and/or length-of-stay between these two groups. Off-pump was done in 48.9% of BIMA cases and 51.3% of LIMA cases. Regardless of the types of grafts used, on-pump patients were more likely to have postoperative permanent strokes and longer postoperative lengths of stay. Use of the BIMA over LIMA-only had a statistically significant impact conferring a 10% survival advantage at 10-year and 18% at 15-year follow-up. The Kaplan-Meier survival curves comparing off-/on-pump BIMA and off-/on-pump LIMA-SVG patients demonstrated a 22% survival advantage for off-pump BIMA patients when compared with on-pump LIMA-SVG patients at 15-year follow-up.

CONCLUSIONS

Perioperative complications do not increase with the use of BIMAs. Long-term survival is optimized with off-pump CABG and BIMA grafting. The low morbidity and mortality rates in this series are likely due to the continuous evolution of technology and the adoption of less invasive options for CABG patients. A more widespread use of BIMAs in CABG patients would continue to improve the overall excellent short- and long-term results of this operation.