Bilateral Internal Mammary Artery Grafting Research Articles

Is Bilateral Internal Mammary Arterial Grafting Beneficial for Patients Aged 75 Years or Older?

Although bilateral internal mammary artery (BIMA) grafting is performed with increasing regularity in elderly patients, whether it is truly beneficial, and therefore indicated, in these patients remains uncertain. We retrospectively investigated early and late outcomes of BIMA grafting in patients aged ≥75 years. We identified 460 patients aged ≥75 years from among 2,618 patients who underwent either single internal mammary artery (SIMA) grafting (n=293) or BIMA grafting (n=107). Early outcomes did not differ between the SIMA and BIMA patients (30-day mortality: 1.7% vs. 0%, P=0.39; sternal wound infection: 1.0% vs. 4.7%; P=0.057). Late outcomes, 10-year survival in particular, were improved in the BIMA group (36.6% vs. 48.1%, P=0.033). In the analysis of the results in propensity score-matched groups (196 patients in the SIMA group, 98 patients in the BIMA group), improved 10-year survival was documented in the BIMA group (34.8% vs. 47.6%, P=0.030). Cox proportional regression analysis showed SIMA usage (non-use of BIMA) to be a predictor for late mortality (hazard ratio: 0.65, 95% confidence interval: 0.43-0.98, P=0.042). We further compared outcomes between the total non-elderly patients (n=2,158) and total elderly patients (n=460). BIMA usage was similar, as was 30-day mortality (1.0% vs. 1.3%, respectively). A survival advantage, with no increase in early mortality, can be expected from BIMA grafting in patients aged ≥75 years. (Circ J 2016; 80: 1756-1763).

Retraction: “Bilateral versus single internal mammary artery grafting in patients with severe coronary artery disease and diabetes mellitus: a systematic review and meta‐analysis” by Yi‐cheng Wu, Jian‐feng Zhang, Guang Ning and Qiang Zhao

The above Accepted Article, published online on 29 June 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editors in Chief, Professor Zachary T. Bloomgarden and Professor Guang Ning, and Wiley Publishing Asia Pty Ltd. The article incorrectly listed Guang Ning and Qiang Zhao as co‐authors, but neither of them actually were involved in the study, or in the writing of the manuscript. Both were included as coauthors without permission.ReferenceWu, Y., Zhang, J., Gao, X., Ning G. and Zhao Q. Bilateral versus single internal mammary artery grafting in patients with severe coronary artery disease and diabetes mellitus: a systematic review and meta‐analysis. Journal of Diabetes, doi: 10.1111/1753‐0407.12320

Impact of the Radial Artery as an Additional Arterial Conduit During In-Situ Bilateral Internal Mammary Artery Grafting: A Propensity Score-Matched Study

Bilateral internal mammary artery (BIMA) grafting has been associated with improved long-term outcomes after CABG. We sought to evaluate the early results and long-term survival among coronary artery bypass graft patients who underwent in-situ BIMA grafting with the radial artery (RA) as an additional arterial conduit compared with those who underwent BIMA with additional saphenous vein graft (SVG). Between 1991 and 2013, 1,750 consecutive patients with triple-vessel disease or left main plus right coronary system disease underwent primary isolated in-situ BIMA grafting with at least one internal mammary artery to the left anterior descending artery. Patients were divided into a BIMA-RA group (n = 255) and BIMA-SVG group (n = 1,495). Propensity score matching was used to create two comparable cohorts: 249 BIMA-RA patients were one-to-one-matched to 249 BIMA-SVG patients. The date of death was obtained from provincial vital statistics. The median follow-up was 8 years. There was no difference in operative mortality between matched BIMA-RA and BIMA-SVG (0.8% versus 0.4%, respectively; p = 0.6). Five-year, 10-year, and 15-year survival rates were 98.3%, 92.0%, and 92.0%, respectively, among BIMA-RA patients, versus 96.5%, 93.0%, and 87.0% in the matched BIMA-SVG group (log rank p = 0.44). When we stratified the BIMA-RA patients into subgroups according to the severity of target artery stenosis, late survival was also similar among the BIMA-RA subgroups matched to BIMA-SVG patients (log rank p = 0.12). The use of the RA as an additional arterial graft in patients undergoing coronary artery bypass graft surgery with in-situ BIMA does not prolong late survival when compared with BIMA patients who received additional SVG.

Abstract 15732: Impact of Bilateral Mammary Artery Grafting for Coronary Revascularization in the Obese Population, a Retrospective Study

Context: The prevalence of obesity has increased over the last decade. Although bilateral internal mammary artery (BIMA) grafting for coronary revascularization is associated with better survival in the general population, it is also a risk factor for deep sternal wound infection (DSWI), a complication more frequently seen in the obese population. The aim of this study is to determine the short and long-term outcomes of the use of BIMA in obese patients undergoing cardiac surgery, assessing the impact on survival and the incidence of DSWI. Methodology: This is a single center retrospective cohort study with prospectively collected data. We included obese patients (BMI ≥ 30 kg/m2) undergoing coronary artery bypass grafting (CABG) between April 1991 and April 2014 in our institution. Propensity score matching was conducted for the entire population studied. Results: Results showed that 5608 obese patients underwent CABG during the study period. After propensity scoring, 494 patients receiving BIMA revascularization were matched to 5089 patients receiving single internal mammary artery (SIMA) revascularization. All pre-operative characteristics were comparable except for a higher prevalence of heart failure in the SIMA group. In-hospital post-operative mortality in the two groups was comparable (1.0% BIMA vs 1.8% SIMA, p=0.86). In-hospital DSWI was also comparable (1.2% BIMA vs 1.0% SIMA, p=0.63). However total DSWI (including post-discharge DSWI, median time 19 days) was significantly higher in the BIMA group compared to the SIMA group (3.6% vs 2.2%; p<0.0001). Over a median follow-up of 7.2 years (mean follow-up 7.7 ± 4.2 years), there was no observed long-term survival advantage in the BIMA vs the SIMA group (p=0.22). Conclusion: Using BIMA instead of SIMA increases the risk of DSWI in obese patients. The use of BIMA is not associated with better survival compared to the use of SIMA in this population. These results suggest that the increased short-term risk of post-operative infection associated with BIMA revascularization is not offset by a long-term survival benefit. Given the increased risk of DSWI and absence of mid- to long-term survival benefit, caution should be exerted when selecting the use of BIMA grafting in the obese population.

Invited Commentary

In this review, Cheng and colleagues [1Cheng K. Rehman S.M. Taggart D.P. A review of differing techniques of mammary artery harvesting on sternal perfusion: time for a randomized study?.Ann Thorac Surg. 2015; 100: 1942-1953Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar] summarize the effect of internal mammary artery (IMA) harvesting on sternal perfusion. In particular, they review the consequences on sternal perfusion of 1) single IMA harvesting, 2) single versus bilateral IMA harvesting, and 3) pedicled versus skeletonized harvesting. Although the findings of the reviewed studies vary, the authors conclude that single IMA harvesting transiently decreases sternal perfusion, particularly in diabetic patients; that bilateral compared with single IMA harvesting does not significantly reduce sternal perfusion; and that skeletonized IMA harvesting results in better sternal perfusion than pedicled harvesting. They suggest that it may be time for a randomized trial.Why does sternal perfusion after IMA harvesting matter? Adequate sternal perfusion is necessary for sternal healing, and inadequate perfusion may increase sternal wound infection. Fear of sternal wound infection is an important deterrent to the widespread adoption of bilateral IMA grafting, despite multiple studies demonstrating that it increases survival and reduces late ischemic events. Another deterrent is that deep sternal wound infection is a “never event” in quality reporting and a metric used in The Society of Thoracic Surgeon’s star rating. Coronary surgeons are caught in the middle. They want to do what is best for their patients; however, the fear of a deep sternal wound infection and its resultant consequences on public reporting, hospital cost, and patient morbidity sway surgeons away from bilateral IMA grafting. In light of these fears, the review by Cheng and colleagues is encouraging. Bilateral IMA harvesting does not appear to result in worse sternal perfusion than single IMA harvesting, and the skeletonized method of harvesting IMAs leads to less devascularization. It may be time for a randomized study, but at least coronary surgeons wanting to do what is best for their patients have a way forward. In this review, Cheng and colleagues [1Cheng K. Rehman S.M. Taggart D.P. A review of differing techniques of mammary artery harvesting on sternal perfusion: time for a randomized study?.Ann Thorac Surg. 2015; 100: 1942-1953Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar] summarize the effect of internal mammary artery (IMA) harvesting on sternal perfusion. In particular, they review the consequences on sternal perfusion of 1) single IMA harvesting, 2) single versus bilateral IMA harvesting, and 3) pedicled versus skeletonized harvesting. Although the findings of the reviewed studies vary, the authors conclude that single IMA harvesting transiently decreases sternal perfusion, particularly in diabetic patients; that bilateral compared with single IMA harvesting does not significantly reduce sternal perfusion; and that skeletonized IMA harvesting results in better sternal perfusion than pedicled harvesting. They suggest that it may be time for a randomized trial. Why does sternal perfusion after IMA harvesting matter? Adequate sternal perfusion is necessary for sternal healing, and inadequate perfusion may increase sternal wound infection. Fear of sternal wound infection is an important deterrent to the widespread adoption of bilateral IMA grafting, despite multiple studies demonstrating that it increases survival and reduces late ischemic events. Another deterrent is that deep sternal wound infection is a “never event” in quality reporting and a metric used in The Society of Thoracic Surgeon’s star rating. Coronary surgeons are caught in the middle. They want to do what is best for their patients; however, the fear of a deep sternal wound infection and its resultant consequences on public reporting, hospital cost, and patient morbidity sway surgeons away from bilateral IMA grafting. In light of these fears, the review by Cheng and colleagues is encouraging. Bilateral IMA harvesting does not appear to result in worse sternal perfusion than single IMA harvesting, and the skeletonized method of harvesting IMAs leads to less devascularization. It may be time for a randomized study, but at least coronary surgeons wanting to do what is best for their patients have a way forward. A Review of Differing Techniques of Mammary Artery Harvesting on Sternal Perfusion: Time for a Randomized Study?The Annals of Thoracic SurgeryVol. 100Issue 5PreviewThe use of internal mammary artery (IMA) grafts for coronary artery bypass may devascularize the sternum. We performed a literature review by searching the PubMed database for studies that assessed sternal perfusion after IMA harvesting. The majority of papers describe various techniques and compared (1) IMA harvest versus no IMA harvest, (2) single versus bilateral, and (3) skeletonized versus pedicled. Evidence is inconclusive as to whether single harvesting causes significant devascularisation and whether this is increased with bilateral harvesting. Full-Text PDF

Hybrid coronary revascularization versus coronary artery bypass surgery with bilateral or single internal mammary artery grafts

ObjectiveHybrid coronary revascularization (HCR) combines minimally invasive left internal mammary artery (LIMA)–left anterior descending artery (LAD) bypass with percutaneous intervention of non-LAD vessels. The purpose of this study was to compare outcomes of HCR to conventional coronary artery bypass graft (CABG) surgery with single internal mammary artery (SIMA) or bilateral internal mammary artery (BIMA) grafting. MethodsBetween October 2003 and September 2013, 306 consecutive patients who underwent HCR were compared with 8254 patients who underwent CABG with SIMA (7381; 89.4%) or BIMA (873; 10.6%) at a US academic center. The primary outcome was a composite of 30-day death, myocardial infarction, and stroke (major cerebrovascular and cardiac event [MACCE]). In addition to multiple logistic and linear regression analysis, a propensity score–matched analysis was used to compare HCR with SIMA and with BIMA. ResultsThe Society of Thoracic Surgeons–predicted risk of mortality was 1.6% for HCR, 2.1% for SIMA, and 1.1% for BIMA (P < .001). Factors associated with HCR use were older age, lower body mass index, history of percutaneous coronary intervention, and 2-vessel disease. In propensity-matched groups, 30-day MACCE rates were comparable (3.3% for HCR vs 1.3% for BIMA [odds ratio (OR), 2.50; P = .12] and vs 3.6% for SIMA [OR, 1.00; P = 1.00]). In-hospital complications were lower after HCR versus SIMA or BIMA (OR, 0.59; P = .033 and OR, 0.55; P = .015, respectively), as was the need for blood transfusion (OR, 0.44; P < .001 and OR, 0.57; P < .001). HCR was associated with shorter hospital stay compared with SIMA (OR, 1.28; P = .038) or BIMA (OR, 1.40; P = .006). No survival difference between matched groups was found at midterm follow-up (HCR vs SIMA: hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.32-1.38; P = .66; HCR vs BIMA: HR, 1.05; 95% CI, 0.48-2.29; P = .91). ConclusionsHCR may represent a safe, less invasive alternative to conventional CABG in carefully selected patients, with similar short-term and midterm outcomes as CABG performed with either SIMA or BIMA grafting.

Bilateral Versus Single Internal Mammary Artery Grafting in the Elderly: Long-Term Survival Benefit

Extensive evidence documents a survival benefit for bilateral internal mammary artery (BIMA) grafting compared with single internal mammary artery (SIMA) grafting for patients with advanced coronary artery disease. However, controversy continues to exist regarding the incremental benefit of broadly applied BIMA grafting in elderly patients. Retrospective analysis was conducted of 4,503 consecutive isolated coronary artery bypass grafting operations (SIMA, n = 2,340 and BIMA, n = 2,163) performed from 1972 to 1994. Multivariate analysis was used to created propensity score-matched groups of SIMA (n = 1,063) and BIMA (n = 1,063) to compare patients 65 years of age and older, and 70 years of age and older (n = 612), with similar baseline characteristics. Survival status was obtained by periodic follow-up, query of the US National Death Index, and other Internet searches, and was 99.6% complete. The propensity score-matched groups experienced similar perioperative mortality and morbidity. Survival benefits were found for BIMA versus SIMA grafting across both age categories. Actuarial curves after 23,593 patient-years of follow-up (mean BIMA = 11.7 years; 6 weeks to 33.1 years; mean SIMA = 10.5 years; 6 weeks to 30.7 years) demonstrated improved long-term survival for BIMA versus SIMA patients at 12 years (51.0 ± 1.5% versus 39.0 ± 1.5%) and at 24 years (3.5 ± 0.7% versus 4.5 ± 0.7%; p < 0.001). Similarly, in matched groups of patients age 70 and older, overall survival was also enhanced with BIMA grafting (p = 0.005). Advanced age should not be a contraindication for BIMA grafting. Long-term follow-up clearly demonstrates that BIMA grafting when broadly applied in elderly patients results in improved long-term survival over SIMA grafting.

Robotic Total Arterial Off-Pump Coronary Artery Bypass Grafting: Seven-Year Single-Center Experience and Long-Term Follow-Up of Graft Patency

Coronary artery bypass grafting (CABG) is the gold-standard treatment for coronary artery disease, but the long-term benefits of robotic CABG remain unclear. Between January 2007 and November 2014, 240 consecutive patients (187 male and 53 female, average age 59 years) underwent robotic off-pump CABG with the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA) in our center. Totally endoscopic coronary artery bypass (TECAB) (n = 100) or mini-thoracotomy coronary artery bypass (MINICAB) (n = 140) grafting was performed with skeletonized internal mammary arteries (IMA). Patients were followed up and graft patency was assessed every 6 months by coronary angiography or 64-multi-slide computed tomographic angiography. All cases were completed without conversion to median sternotomy or cardiopulmonary bypass. A total of 237 single IMA grafts (98.3%) and 4 bilateral IMA grafts (1.7%) were used. No operative mortality was observed. Hybrid revascularization of non-left anterior descending vessels was performed in 24 patients (10%). No death, stroke, or myocardial infarction occurred in the follow-up of 41.1 ± 12.9 months. All grafts were patent before discharge. The IMA graft patency was 97.1% in TECAB and 96.4 % in MINICAB over 3 years (up to 91 months) postoperatively. Robotic off-pump CABG using IMA grafts is a safe and effective procedure in selected patients. The long-term outcome and patency of IMA grafts are excellent.

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.

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

Potential Risk Factors for Surgical Site Infection after Isolated Coronary Artery Bypass Grafting in a Bahrain Cardiac Centre: A Retrospective, Case-Controlled Study.

Objective:The purposes of this study were to determine the incidence of surgical site infections (SSI) and associated risk factors in patients undergoing isolated coronary artery bypass grafting (CABG) in our cardiac center during a 2-year period.Materials and Methods:Retrospective case-control analysis for 80 patients who underwent isolated cardiac surgery CABG. These patients were divided into the SSI study group (n = 40) and the noninfected control group (n = 40). Eight potential perioperative risk variables were compared between the two groups using univariate logistic regression analysis.Results:Univariate analysis was carried out for eight potential risk factors. The risk factors found to be significant were: Impaired estimated glomerular filtration rate (P = 0.011) and impaired left ventricular ejection fraction (P = 0.015). However, Factors found to have no significant influence on the incidence of SSIs were: Perioperative length of hospital stay (days), urgency of surgery, use of bilateral internal mammary artery (BIMA) grafting, prolonged cardiopulmonary bypass duration, elevated body mass index.Conclusions:Patients with comorbidities of impaired renal function and/or impaired left ventricular systolic function are at high risk of developing SSI. There appears to be a relationship between SSIs in CABG patients and impaired renal or LV function (low ejection fraction). CABG with BIMA grafting could be performed safely even in diabetics. Future studies should consider further scrutiny of these and other factors in relation to SSIs in a larger surgical population.

Impact of pump status and conduit choice in coronary artery bypass: A 15-year follow-up study in 1412 propensity-matched patients

Previous studies have demonstrated that bilateral internal mammary artery (BIMA) grafts lead to superior outcomes compared with single internal mammary artery grafts. This study examines whether cardiopulmonary bypass affects conduit-dependent outcomes of coronary artery bypass grafting (CABG) surgery. From 1994 to 2013, a total of 6666 patients underwent isolated CABG surgery at our institution. Of these procedures, 3548 (53.2%) were performed off pump. A BIMA-saphenous vein graft (SVG) was used in 1544, and 5122 had left internal mammary artery-SVGs. These 2 conduit groups differed significantly in baseline characteristics. Propensity matching based on 22 preoperative variables and using a nearest-neighbor matching algorithm was used to make balanced cohorts, resulting in 2 groups of 1006. To account for the influence of pump status on conduit selection, a second propensity score was developed for pump use. These cases were matched to create 4 patient cohorts of 353 patients each (a total of 1412), balanced for both conduit use and pump status. Late mortality was determined using the Social Security Death Index. No difference was found in survival between patients receiving BIMA-SVGs on or off pump (78.9% vs 79.1%). BIMA-SVGs outperformed the left internal mammary artery-SVGs regardless of whether the procedure was performed off pump (73.9%) or on pump (69.9%). This study demonstrates that the use of cardiopulmonary bypass does not significantly affect the long-term outcomes in these patients as long as full revascularization is achieved. In addition, these results are consistent with prior research showing that the use of BIMAs produces better outcomes than use of a single internal mammary artery when performing CABG.

Effects of on-pump and off-pump surgery in the Arterial Revascularization Trial.

The Arterial Revascularization Trial (ART) is a randomized comparison of bilateral internal mammary artery (BIMA) versus single internal mammary artery (SIMA) grafting in coronary artery bypass graft (CABG) surgery and is one of the largest randomized trials of surgery ever conducted. ART is also one of the largest studies of contemporary CABG with a high proportion of off-pump surgeries (41%). The objective of this post hoc analysis was to evaluate the surgical process and 1-year outcomes for surgery performed on-pump compared with off-pump. ART randomized 3102 patients with multivessel coronary artery disease (CAD) to SIMA or BIMA grafts to determine if BIMA grafts have an additional survival advantage at 10 years. The 1-year interim analysis showed an overall very low mortality and major morbidity rate irrespective of whether the procedure was with an SIMA or BIMA. The surgical process and 1-year outcomes were analysed according to whether surgery was performed on-pump or off-pump. Baseline variables were not statistically significantly different between on- and off-pump surgery within each treatment group after taking account of the effects of clustering by individual surgeons. At both 30 days and 1 year, there was a low incidence of death (1.2%, 2.3%), stroke (1.1%, 1.7%), myocardial infarction (MI) (1.4%, 1.9%), repeat revascularization (0.5%, 1.5%) and wound reconstruction (1.2%). A similar average number of grafts were performed with on- and off-pump surgery (median = 3), but the duration of surgery was 20-30 min and ventilation time ∼ 2 h shorter with off-pump surgery. Blood loss and platelet transfusions were lower in the off-pump group, with no difference in the need for balloon pump or renal support. Sternal wound reconstruction was similar with off-pump surgery in the SIMA group (0.5 vs 0.6%) and lower with off-pump surgery in the BIMA group (1.4 vs 2.2%). Repeat revascularization was marginally higher in off-pump patients at 30 days (0.8 vs 0.3%) and at 1 year (1.7 vs 1.3%). The outcomes of contemporary CABG are excellent with low mortality, stroke, myocardial infarction and need for wound reconstruction and repeat revascularization whether performed on-pump or off-pump. Controlled-trials.com (ISRCTN46552265).

Effect of bilateral internal mammary artery grafts on long-term survival: a meta-analysis approach.

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. 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. 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.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

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

BackgroundPrior 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 ResultsPatients 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).ConclusionsBIMA 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.

EComment. Two internal mammary artery grafts are better than one

We read with great interest the paper by Smith et al. regarding the long-term survival benefit of the usage of bilateral internal mammary artery (BIMA) grafts in coronary revascularization surgery [1]. They included in their results 13 follow-up studies published after 2001. However, we found one additional relevant article investigating the long-term outcomes associated with BIMA grafting compared with single internal mammary artery (SIMA) among diabetic patients [2]. We would like to take this opportunity to briefly extract the relevant information from the above-mentioned study and to add a short comment on this salient subject. Puskas et al. [2] conducted a retrospective cohort analysis by extracting data from the Society of Thoracic Surgeons database at a single referral academic centre. They included a total of 3527 coronary artery bypass grafting procedures (BIMA n = 812, SIMA n = 2715). After adjustment for differences between groups by the Cox model, BIMA grafting portended a 35% reduction in the hazard of long-term death at 8 years of follow-up (adjusted hazard ratio, 0.65; 95% CI, 0.48 to 0.88, P = 0.006). The authors concluded that the usage of BIMA grafting provides significant benefit in late survival compared with SIMA grafting in both diabetic and non-diabetic patients. BIMA grafting should be performed whenever patient risk factors and comorbidities allow an acceptable risk of deep sternal wound infection. As rightly outlined by the authors, all these studies are follow-up studies. However, only one randomized trial comparing these two techniques (ART Arterial Revascularization Trial) [3] is currently under way in Europe that can broaden our understanding. ART primary outcome is survival at 10 years; therefore the results should be available by 2018. Until that date the debate will continue. This uncertainty has been reflected in the rate of adoption of BIMA grafting, the rate of use of the technique varies from 4% in North America to 10% in Europe [4]. The major reasons for not using BIMA grafts are the lack of solid evidence of benefits and the increased rate of sternal wound infection, particularly in diabetics. Of note, in the SYNTAX study [5], BIMA grafting was used in a relatively higher percentage of 28% of patients. The more liberal use of BIMA in this trial entails a paradigm shift in grafting strategies worldwide.

Arterial grafting and complete revascularization

Arterial grafting is superior to venous grafting in coronary artery bypass graft surgery with respect to graft patency and long-term patient outcome, but it may be difficult to achieve complete arterial revascularization. Use of arterial grafts, especially bilateral internal mammary artery grafts, is not common, whereas there are clear indications that it may increase survival. Definitions of complete revascularization are varied and confusing, making study comparisons difficult. Technical challenges in complete revascularization with arterial grafts can be minimized by surgical techniques. Competitive flow in moderately stenosed coronary arteries grafted with arterial conduits may result in reduced patency. While internal mammary arteries may be used in arteries with at least 60% stenosis, radial artery and gastroepiploic grafts are best placed onto coronaries with severe stenosis. Moderate lesions in the left coronary circulation should be bypassed, but right coronary artery lesions can be left untouched as there is minimal progression over time. Complete revascularization may not be necessary or possible in every patient because of technical challenges. Complete revascularization with arterial grafts presents both technical and physiological challenges. However, with techniques to maximize length of arterial conduits, knowledge of competitive flow and which moderate lesions should be addressed, complete revascularization with arterial grafts can be accomplished in the majority of patients, notwithstanding it may not be possible or even indicated for every patient.

Arterial grafts balance survival between incomplete and complete revascularization: A series of 1000 consecutive coronary artery bypass graft patients with 98% arterial grafts

Coronary artery bypass grafting (CABG) with incomplete revascularization (ICR) is thought to decrease survival. We studied the survival of patients with ICR undergoing total arterial grafting. In a consecutive series of all-comer 1000 patients with isolated CABG, operative and midterm survival were assessed for patients undergoing complete versus ICR, with odds ratios and hazard ratios, adjusted for European System for Cardiac Operative Risk Evaluation category, CABG urgency, age, and comorbidities. In this series of 1000 patients with 98% arterial grafts (2922 arterial, 59 vein grafts), 73% of patients with multivessel disease received bilateral internal mammary artery grafts. ICR occurred in 140 patients (14%). Operative mortality was 3.8% overall, 8.6% for patients with ICR, and 3.2% for patients with complete revascularization (P=.008). For operative mortality using multivariable logistic regression, after controlling for European System for Cardiac Operative Risk Evaluation category (P<.001) and CABG urgency (P=.03), there was no evidence of a statistically significant increased risk of death due to ICR (odds ratio, 1.73; 95% confidence interval, 0.80-3.77). For midterm follow-up (median, 54 months [interquartile range, 27-85 months]), after controlling for European System for Cardiac Operative Risk Evaluation category (P<.001) and comorbidities (P=.017) there was a significant interaction between age ≥ 80 years and ICR (P=.017) in predicting mortality. The adjusted hazard ratio associated with ICR for patients older than age 80 years was 5.7 (95% confidence interval, 1.8-18.0) versus 1.2 (95% confidence interval, 0.7-2.1) for younger patients. This is the first study to suggest that ICR in patients with mostly arterial grafts is not associated with decreased survival perioperatively and at midterm in patients younger than age 80 years. Arterial grafting, because of longevity, may balance survival between complete revascularization and ICR.

Full myocardial revascularization with bilateral internal mammary artery Y grafts.

Bilateral internal mammary artery (BIMA) grafting in coronary artery surgery provides better long term outcomes than single internal mammary artery and saphenous vein grafting but the optimum configuration of BIMAs has not been established. This study analyzed perioperative and late outcomes of patients who underwent BIMA grafting with a composite Y configuration. Patients (n=922) who underwent BIMA Y grafting were identified from a cardiac surgical database and then cross matched against hospital and cardiology databases and the state death register to identify episodes of repeat coronary angiography, cardiac surgical re-intervention and death. Analysis of repeat angiography was performed after retrieval of the angiogram reports. In 95% of patients, full myocardial revascularization was achieved with BIMAs alone, using a composite Y configuration with an average of 4.1 IMA to coronary artery anastomoses per patient. The perioperative mortality was 1.5% and the 5-, 10- and 15-year survival estimates were 95%, 87% and 77% respectively. Analysis of 166 symptom-driven post-discharge coronary angiograms showed grafts to the left anterior descending artery and increasing severity of coronary artery stenosis at preoperative angiography as predictors of anastomotic patency. Full myocardial revascularization can be achieved with reasonable safety in most patients with triple vessel disease and good left ventricular function, and provides good late survival.

Bilateral internal mammary arteries: evidence and technical considerations.

Bilateral internal mammary artery (BIMA) grafts are used for coronary revascularisation by only a minority of surgeons, despite a growing body of evidence suggesting improved survival when compared to use of only one internal mammary artery with additional saphenous vein grafts. Herein we review the evidence supporting revascularisation with BIMA and suggest reasons why the majority of surgeons use only one internal mammary artery. We discuss technical considerations, various graft combinations and the use of BIMA to facilitate anaortic off-pump coronary artery bypass (OPCAB).