Thirty-Year Experience with Bilateral Internal Thoracic Artery Grafting: Where Have We Been and Where Are We Going?

Effect of bilateral internal thoracic artery harvesting on deep sternal wound infection in diabetic patients: Review of literature

Instead of its documented superiority of patency and long-term outcomes, the bilateral internal thoracic artery grafts are underused in the general population, and its use is controversial and debatable in diabetic patients due to long surgery duration, post-surgical bleeding, and sternal wound complications such as sternal wound infection, mediastinitis, and sternal wound dehiscence. This review article is particularly focused on deep sternal wound infection (DSWI) of bilateral internal thoracic artery (BITA) grafts in diabetic patients with comparison to single internal thoracic artery (SITA) graft.

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Bilateral internal thoracic artery grafting is superior to single internal thoracic artery grafting in terms of outcomes.

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Bilateral internal thoracic artery grafting is underused, especially in diabetic patients.

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The risk of DSWI in skeletonized BITA grafting in diabetic patients is almost similar to SITA grafting.

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Skeletonized BITA grafting should be encouraged in selected diabetic patients.

The long-term patency of a gastroepiploic artery bypass graft deployed in a semiskeletonized fashion: predictors of patency

OBJECTIVES

Whether or not using the gastroepiploic artery (GEA) is associated with improved outcomes of coronary artery bypass grafting (CABG) remains unclear. Previous research has shown that the short-term function of the GEA was strongly associated with the degree of native vessel stenosis. We assessed the association between long-term GEA patency and the degree of stenosis of the coronary artery.

METHODS

We retrospectively examined 517 patients who underwent CABG with an in situ semiskeletonized GEA from January 2000 to January 2015. In this cohort, 282 (54.5%) patients underwent distant radiological evaluations for >1 year post-surgery (range 1-18 years after surgery). Quantitative coronary angiography was used to measure the degree of stenosis of the native coronary artery. Preoperative angiographic parameters include the minimal lumen diameter (MLD) and the percentage of target vessel stenosis. A multivariable stepwise Cox proportional hazards regression analysis was used to identify predictors of angiographic occlusion.

RESULTS

The cumulative patency rate of the GEA was 79.3% at 10 years. A multivariable analysis showed that an MLD (hazard ratio 4.43, 95% confidence interval 3.25-6.82; P < 0.001) was an independent risk factor of GEA occlusion. A time-dependent receiver operating characteristic (ROC) curve analysis identified that an MLD >1 mm was set as the cut-off value for graft occlusion. Patients with an MLD <1 mm had a 10-year patency rate of 89.8%.

CONCLUSIONS

The long-term patency of the semiskeletonized GEA was acceptable. The target vessel MLD obtained using quantitative coronary angiography was a strong predictor of patency. Good long-term patency can be expected for an MLD <1 mm.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Randomized Trial of Bilateral versus Single Internal-Thoracic-Artery Grafts

BACKGROUND

The use of bilateral internal thoracic (mammary) arteries for coronary-artery bypass grafting (CABG) may improve long-term outcomes as compared with the use of a single internal-thoracic-artery plus vein grafts.

METHODS

We randomly assigned patients scheduled for CABG to undergo single or bilateral internal-thoracic-artery grafting in 28 cardiac surgical centers in seven countries. The primary outcome was death from any cause at 10 years. The composite of death from any cause, myocardial infarction, or stroke was a secondary outcome. Interim analyses were prespecified at 5 years of follow-up.

RESULTS

A total of 3102 patients were enrolled; 1554 were randomly assigned to undergo single internal-thoracic-artery grafting (the single-graft group) and 1548 to undergo bilateral internal-thoracic-artery grafting (the bilateral-graft group). At 5 years of follow-up, the rate of death was 8.7% in the bilateral-graft group and 8.4% in the single-graft group (hazard ratio, 1.04; 95% confidence interval [CI], 0.81 to 1.32; P=0.77), and the rate of the composite of death from any cause, myocardial infarction, or stroke was 12.2% and 12.7%, respectively (hazard ratio, 0.96; 95% CI, 0.79 to 1.17; P=0.69). The rate of sternal wound complication was 3.5% in the bilateral-graft group versus 1.9% in the single-graft group (P=0.005), and the rate of sternal reconstruction was 1.9% versus 0.6% (P=0.002).

CONCLUSIONS

Among patients undergoing CABG, there was no significant difference between those receiving single internal-thoracic-artery grafts and those receiving bilateral internal-thoracic-artery grafts with regard to mortality or the rates of cardiovascular events at 5 years of follow-up. There were more sternal wound complications with bilateral internal-thoracic-artery grafting than with single internal-thoracic-artery grafting. Ten-year follow-up is ongoing. (Funded by the British Heart Foundation and others; ART Current Controlled Trials number, ISRCTN46552265 .).

Multiple arterial grafting for coronary revascularization: "A guide for the perplexed"

The surgical literature abounds with articles extolling the benefits of arterial grafting for patients with advanced coronary artery disease in need of surgical revascularization. However, examination of clinical performance demonstrates that extensive use of arterial grafting is highly selective and generally uncommon. Rather than to merely repeat multiple excellent recent literature reviews, the goal herein is to provide the reader with a guide to the evaluation of the current literature as well as to suggest fruitful areas for further research. More circumspect understanding of the strengths and weaknesses of our current knowledge base will not only help to explain the current apparent disparity between theory and practice but will hopefully inform future decision-making and patient care.

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.

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.

Mysterious abdominal pain

A man presented to the emergency room with recurrent episodes of abdominal pain. He had a history of coronary artery bypass grafting of the left internal mammary artery (LIMA) to the left anterior descending (LAD) artery and the right gastroepiploic artery to the posterior descending artery. After numerous gastrointestinal evaluations, a stress test was performed, which was positive. Coronary angiography showed a proximal occlusion of the LAD and right coronary artery and a normal functioning LIMA bypass. Aortography showed a 95% stenosis of the celiac trunk. Angioplasty and stent implantation of the celiac trunk was successfully performed. Six months later the patient was completely asymptomatic with a negative stress test. In conclusion, abdominal pain in patients who have undergone coronary artery bypass surgery using the right gastroepiploic artery should raise suspicion not only of a stenosis of the arterial conduit but also of a potential stenosis of the celiac trunk.

'No-touch' saphenous vein harvesting improves graft performance in patients undergoing coronary artery bypass surgery: a journey from bedside to bench

The saphenous vein is the most commonly used conduit in patients undergoing coronary artery bypass surgery yet its patency is inferior to the internal thoracic artery. Vascular damage inflicted to the vein when using conventional harvesting techniques affects its structure. Endothelial denudation is associated with early vein graft failure while damage of the outermost vessel layers has adverse long-term effects on graft performance. While many in vitro and in vivo experimental studies aimed at improving vein graft patency have been performed to date no significant 'bench to bedside' advances have been made. Among experimental strategies employed is the use of pharmacological agents, gene targeting and external stents. A 'no-touch' technique, where the saphenous vein is removed with minimal trauma and normal architecture preserved, produces a superior graft with long term patency comparable to the internal thoracic artery. Interestingly, many experimental studies are aimed at repairing or replacing those regions of the saphenous vein damaged when harvesting conventionally. 'No-touch' harvesting is superior in coronary artery bypass patients with long-term data published 5years ago. Here we describe a 'bedside to bench' situation where the mechanisms underlying the improved performance of 'no touch' saphenous vein grafts in patients have been studied in the laboratory.

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.

Human internal thoracic artery grafts exhibit severe morphological and functional damage and spasmic vasomotion due to oxidative stress

Background

The internal thoracic artery (ITA) is the first choice for myocardial revascularization, but atherosclerotic lesions and perioperative vasospasm may still limit its functionality. Oxidative stress via the peroxynitrite – poly-(ADP-ribose) polymerase (PARP) cascade plays an important role in the pathogenesis of impaired vascular tone via endothelial injury. We aimed to investigate and describe the histology, PARP activation and functionality of ITA grafts and to assess the possible beneficial effect of PARP-inhibition.

Material/Methods

ITA specimens from 47 patients (26 men, mean age 66.2±1.7 years) who underwent coronary bypass surgery were processed for histological and immunohistochemical studies for oxidative stress and PARP activation, and were functionally tested with acetylcholine (ACh) and sodium nitroprusside (SNP) with or without PARP inhibition.

Results

The sections showed atherosclerotic alterations and oxidative and nitrosative stress were evidenced by positive 3-nitrotyrosine, 4-hydroxynonenal and PAR stainings. Functionally, 88.1% reacted to K-Krebs, 68.7% exhibited contraction after 1 μM phenylephrine, 29.9% exhibited relaxation to 30 μM Ach, and all precontracted segments relaxed to 30 μM SNP. High amplitude vasomotion was observed in 47.8% of the segments, which could be abolished by the application of 10 μM SNP. Incubation of the preparations with PJ34 did not improve endothelium-dependent vasodilation.

Conclusions

ITA grafts are severely damaged both morphologically and functionally in patients undergoing coronary artery bypass surgery, but PARP inhibition cannot improve their functional characteristics. The topical use of SNP to the ITA during the operation may improve vascular functions by dilating the vessels and eliminating the eventual spasmic vasomotion.

Randomized trial to compare bilateral vs. single internal mammary coronary artery bypass grafting: 1-year results of the Arterial Revascularisation Trial (ART)

AIMS

Observational data suggest that the use of bilateral internal mammary arteries (BIMA) during coronary artery bypass graft surgery provides superior revascularization to a single internal mammary artery (SIMA), but concerns about safety have prevented the widespread use of BIMA. The Arterial Revascularisation Trial (ART) is a randomized trial of BIMA vs. SIMA, with a primary outcome of survival at 10 years. This paper reports mortality, morbidity, and resource use data at 1 year.

METHODS AND RESULTS

Coronary artery bypass graft patients were enrolled in 28 hospitals in seven countries. Three thousand one hundred and two patients were randomly assigned to SIMA (n = 1554) or BIMA (n = 1548). The mean number of grafts was 3 for both groups. Forty per cent of the SIMA procedures and 42% of the BIMA were performed off-pump. Mortality at 30 days was 18 of 1548 (1.2%) for SIMA and 19 of 1537 (1.2%) for BIMA, and at 1 year was 36 of 1540 (2.3%) and 38 of 1529 (2.5%), respectively. The rates of stroke, myocardial infarction, and repeat revascularization were all ≤2% at 1 year and similar between the two groups. Sternal wound reconstruction was required in 0.6 and 1.9% of the SIMA and BIMA groups, respectively.

CONCLUSION

Data from ART demonstrate similar clinical outcomes for SIMA and BIMA at 1 year but BIMA grafts are associated with a small absolute increase (1.3%) in the need for sternal wound reconstruction. The results suggest that the use of BIMA grafts is feasible on a routine basis. The 10-year results of the ART will confirm whether BIMA grafting results in lower mortality and the need for repeat intervention.

TRIAL REGISTRATION

Controlled-trials.com (ISRCTN46552265).