Bilateral Internal Mammary Artery Patients Research Articles

Outcomes of Coronary Artery Bypass Grafting With Bilateral Internal Mammary Artery in Obese Patients

BackgroundThe purpose of this study was to evaluate postoperative outcomes with the use of bilateral internal mammary artery (BIMA) conduits in obese patients. MethodsBetween January 2003 and December 2018, 8109 patients underwent isolated coronary artery bypass grafting, including 7218 (89%) treated with single internal mammary artery (SIMA) and 891 (11%) treated with BIMA grafts. Patients were divided into 3 groups according to preoperative body mass index (BMI): normal, BMI <25 kg/m2 (22.2%); overweight, BMI of 25 to <30 kg/m2 (37.2%); and obese, BMI ≥30 kg/m2 (40.6%). In each group, BIMA and SIMA patients were compared to investigate 30-day mortality and postoperative complications. Significant baseline differences were observed between the 3 BMI groups, and such differences were adjusted by inverse probability weighting matching. ResultsThirty-day mortality, deep sternal wound infection (DSWI) rates, and length of hospital stay were 1.4%, 0.5%, and 6.0 ± 9.1 days for the normal group; 0.2%, 1.0%, and 5.5 ± 4.2 days for the overweight group; and 0.9%, 1.8%, and 5.5 ± 4.0 days for the obese group. There was no significant difference in 30-day mortality, incidence of DSWI, and hospital stay between BIMA and SIMA groups, except in the obese group, in which the rate of DSWI was significantly higher in the BIMA patients (3.4% vs 0%; P = .02). ConclusionsBIMA grafts in obese patients can be used without an increase of the 30-day mortality and hospital stay. However, the use of BIMA grafts in obese patients may lead to an increase of postoperative DSWI.

Abstract 13096: Outcomes After Coronary Artery Bypass Grafting With Bilateral Internal Mammary Arteries in Obese Patients

Introduction: The purpose of this study was to evaluate the postoperative outcomes with the use of bilateral internal mammary artery (BIMA) conduits in obese patients. Methods: Between January 2003 and December 2018, 8109 patients underwent isolated coronary artery bypass grafting (CABG) at our institution, including 7218 (89.0%) treated with single internal mammary artery (SIMA) and 891 (11.0%) treated with BIMA. Patients were divided into three groups according to preoperative body mass index (BMI), normal or BMI&lt;25 (22.2%), overweight or 25-BMI&lt;30 (37.2%), and obese or BMI&gt;30 (40.6%). In each group, BIMA and SIMA patients were compared to investigate the thirty-day mortality and postoperative complications. Significant baseline differences were observed between the three BMI groups and such differences were adjusted via inverse probability weighting matching. Results: The thirty-day mortality, deep sternal wound infection (DSWI) rates and length of hospital stay were 1.4%, 0.5%, and 6.0 ± 9.1 days for the normal group, 0.2%, 1.0% and 5.5 ± 4.2 days for overweight group and 0.9%, 1.8% and 5.5 ± 4.0 days for the obese group. There was no significant difference in the thirty-day mortality, incidence of DSWI and hospital stay between BIMA and SIMA groups, except in the obese group where the rate of DSWI was significantly higher in the BIMA patients (3.4 vs 0.0%, p=0.02). Conclusions: BIMA for isolated CABG in obese patients can be used without an increase of the thirty-day mortality and hospital stay. However, the use of BIMA in obese patients may lead to an increase of postoperative DSWI.

Bilateral vs Single Internal Mammary Artery Grafts for Coronary Artery Bypass in the United States

The use of the bilateral internal mammary artery (BIMA) in coronary artery bypass grafting remains controversial. The objective of this study was to investigate the long-term outcomes using the BIMA vs the single internal mammary artery (SIMA) in the United States. Medicare beneficiaries who underwent primary isolated coronary artery bypass surgery using the SIMA or BIMA from 1999 to 2010 were included in this retrospective study, with follow-up through 2014. Greedy matching algorithms were used for 1:4 matching on propensity score based on age, gender, year of surgery, and comorbidities. Kaplan-Meier survival analyses were performed. The primary outcome was death from any cause. A total of 1,156,339 and 25,005 patients who were 72 ± 7.6 years of age and 70.3 ± 7.9 years of age underwent primary isolated coronary artery bypass surgery using SIMA and BIMA, respectively. Matching created comparable groups with 95,780 SIMA and 24,160 BIMA patients. Matched median survival using SIMA vs BIMA was 11.8 vs 12.4 years (P < .001) and 9.6 vs 10 years in diabetic patients (P = .006), respectively. At 10 years of follow-up, the respective survival rates of using SIMA vs BIMA were 58.3% vs 61.1%, respectively. The stratified matched median survival using SIMA vs BIMA with 1, 2, 3, and 4 or more aortocoronary bypasses were 11.8 vs 12.3 years (P= .005), 11.7 vs 12.5 years (P < .001), 11.9 vs 12.3 years (P= .01), and 11.4 vs 12 years (P= .02), respectively. Primary isolated coronary artery bypass surgery using the BIMA rather than the SIMA was associated with improved long-term survival. This survival advantage was independent of aortocoronary bypass grafts or patient diabetes status.

Bilateral Internal Mammary Artery Use in Diabetic Patients: Friend or Foe?

Bilateral internal mammary artery (BIMA) grafting in diabetic patients undergoing coronary artery bypass grafting remains controversial. Our study compared morbidity and mortality between (1) diabetic and nondiabetic BIMA patients and (2) diabetic BIMA versus diabetic patients who underwent left internal mammary artery (LIMA) grafting only. Patients who underwent isolated coronary artery bypass grafting from July 2011 to June 2016 at any of the 10 Maryland Cardiac Surgery Quality Initiative centers were propensity scored across 16 variables. Diabetic BIMA patients were matched 1:1 by nearest neighbor matching to nondiabetic BIMA patients and were separately matched 1:1 to diabetic LIMA patients. We calculated observed-to-expected (O/E) ratios for composite morbidity/mortality, operative mortality, unplanned reoperation, stroke, renal failure, prolonged ventilation, and deep sternal wound infection and compared ratios among matched populations. During the study period, 812 coronary artery bypass grafting patients received BIMA grafts, including 302 patients (37%) with diabetes. We matched 259 diabetic and nondiabetic BIMA patients. O/E ratios were higher in matched diabetic (versus nondiabetic) BIMA patients when comparing composite morbidity/mortality, reoperation, stroke, renal failure, and prolonged ventilation (all O/E ratios >1.0); however, the O/E ratio for operative mortality was higher in nondiabetic BIMA patients. We additionally matched 292 diabetic BIMA to diabetic LIMA patients. Diabetic BIMA patients had a higher O/E ratio for composite morbidity/mortality, operative mortality, stroke, renal failure, and prolonged ventilation. In this statewide analysis, diabetic patients who received BIMA grafts (compared with diabetic patients with LIMA grafts or nondiabetic patients with BIMA grafts) had higher O/E ratios for composite morbidity/mortality as a result of higher O/E ratios for major complications.

Systematic bilateral internal mammary artery grafting: lessons learned from the CATHolic University EXtensive BIMA Grafting Study.

Despite claims of feasibility, to date no study has examined the effect of systematic bilateral internal mammary artery (BIMA) use in a large cohort of real-world unselected patients. The CATHolic University EXtensive BIMA Grafting Study (CATHEXIS) registry was designed to assess the feasibility and safety of systematic BIMA grafting. The CATHEXIS was a single-centre, prospective, observational, propensity-matched study. The study was supposed to include 2 arms of 500 patients each: a prospective arm and a retrospective arm. The prospective arm included almost all patients referred for coronary artery bypass grafting (CABG) at our institution after the start of the CATHEXIS with very few exceptions. BIMA would have been used in all these patients. The retrospective arm included patients submitted to CABG before the start of the CATHEXIS and propensity matched to the prospective group (average BIMA use 50%; the radial artery was extensively used). Safety analyses were scheduled after enrolment of 200, 300 and 400 BIMA patients. After the first 226 patients, the BIMA use percentage was 88.5% (200 of 226). In 178 (89%) patients, mammary arteries were used as Y graft. Postoperative mortality was 2%, and incidence of perioperative myocardial infarction, graft failure and sternal complications were 3.5%, 3% and 5.5%, respectively. No perioperative stroke occurred. The incidence of major adverse cardiac events (particularly graft failure and sternal complications) in the BIMA arm were significantly higher than those in the propensity-matched cohort; the study was stopped for safety. In a real world setting the systematic use of BIMA was associated with a higher incidence of perioperative adverse events (particularly sternal complications). Individualization of the revascularization strategy and use of alternative arterial conduits are probably preferable to systematic use of BIMA.

Should Diabetes Be a Contraindication to Bilateral Internal Mammary Artery Grafting?

This study evaluates the influence of bilateral internal mammary artery (BIMA) versus single internal mammary artery (SIMA) grafting on postoperative morbidity and long-term survival among diabetic patients undergoing coronary artery bypass grafting (CABG). A multicenter, retrospective analysis of 47,984 consecutive CABGs performed from 1992 to 2014 at 7 medical centers was conducted. Among the study population, 1,482 CABGs with BIMA were identified, and 1,297 BIMA patients were propensity-matched to 1,297 SIMA patients. The study cohort for this analysis, drawn from matched data, included 430 diabetic patients: 217 SIMA and 213 BIMA. The primary endpoint was long-term survival. Secondary endpoints included postoperative morbidity, length of stay, and in-hospital mortality. The median duration of follow-up was 9.3 (range, 4.3 to 13.9) years. Among propensity-matched diabetic patients, there was no significant difference in age, body mass index, or major baseline comorbidities. The groups were also well matched on the number of diseased coronary arteries and number of distal anastomoses performed. There was no difference in the rate of mediastinitis or sternal dehiscence (p= 0.503) or in-hospital mortality (p= 0.758) between groups. Both groups had a similar median length of stay of 5 (range, 4 to 7) days. Diabetic patients who received a BIMA had significantly improved long-term survival when compared with SIMA patients (hazard ratio 0.75 [95% confidence interval 0.57 to 0.98], p= 0.034). Among diabetics undergoing CABG, use of BIMA grafting does not result in increased in-hospital morbidity or mortality and confers a long-term survival advantage when compared with SIMA grafting. Thus, diabetic patients should be considered for BIMA grafting more frequently.

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).

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.

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.

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.

Propensity-matched analysis of bilateral internal mammary artery vs single internal mammary artery in 7702 cases of isolated coronary artery bypass grafting†

To evaluate early outcomes of bilateral internal mammary artery (BIMA) compared with single IMA (SIMA) in patients who underwent isolated coronary artery bypass grafting (CABG). Patients who received isolated CABG with SIMA or BIMA were retrospectively reviewed using the Japan Adult Cardiovascular Surgery Database from 210 institutions for 2008 and 2009. We performed a one-to-one matched analysis on the basis of estimated propensity scores for patients receiving either SIMA or BIMA and obtained two cohorts with 3851 patients in each group balanced for baseline characteristics out of 8136 SIMA and 4093 BIMA patients. We compared procedures actually performed, early outcomes including 30-day operative mortality and details of postoperative complications between the groups using Pearson's chi-square test, with P < 0.05 being statistically significant. Preoperative profiles in both groups included 20% females and 50% diabetes mellitus patients with a mean age of 67 years. Off-pump CABG was similar in both groups, being performed 75% of the time, with the mean number of anastomosis being 3.1 and 3.4 in the SIMA and BIMA groups, respectively (P < 0.0001). Thirty-day operative mortality was 1.2% in both groups, and the overall incidence of postoperative complications also was similar, although deep sternal infection was more frequent with BIMA (1.3 of SIMA and 2.3% of BIMA patients; P = 0.0001), while prolonged ventilation and renal failure were more frequent with SIMA (P < 0.05). The use of BIMA did not affect either short-term survival as postoperative mortality was low in both groups, or overall morbidity despite higher incidence of deep sternal infection.

Circulation: Clinical Summaries

<i>Circulation:</i> Clinical Summaries

Risks of bilateral internal mammary artery bypass grafting

Although use of one internal mammary artery (IMA) for coronary artery bypass grafting does not appear to be associated with increased risk, the results with both IMAs are less certain; the potential for a higher incidence of sternal wound infection as a result of devascularization of the sternum is a major concern. During a 42-month interval ending July 1988, 1,566 patients had coronary artery bypass grafting alone or in combination with other procedures: 633 received only vein grafts, 687 had unilateral IMA grafting, and 246 had bilateral IMA grafting. The IMA patients were younger, were more often male, had better cardiac function, and underwent fewer emergent, urgent, or combined procedures than the patients receiving vein grafts ( p < 0.05). Thirty-day mortality was lower among the IMA patients (unilateral IMA group, 2.8%; bilateral IMA group, 3.7%; and vein graft group, 7.9%; p = 0.001). With the exception of sternal wound problems, occurrence rates for postoperative complications among the IMA patients did not differ significantly from or were lower ( p < 0.05) than those among the patients with vein grafts. Sternal infections occurred with greater frequency among the bilateral IMA patients (6.9%) than among the unilateral IMA (1.9%) or vein graft (1.3%) patients ( p = 0.001). By univariate analysis, obesity, diabetee, bilateral IMA grafting, and need for prolonged (>48 hours) mechanical ventilation were associated with a significantly higher incidence of sternal infection ( p < 0.05). Multivariate logistic regression analysis identified use of bilateral IMA grafts ( p = 0.0001), obesity ( p = 0.0014), and prolonged mechanical ventilation ( p = 0.0018) as significant risk factors for the development of sternal infection. We conclude that bilateral IMA grafting is an important predictor of sternal infection. It should be used selectively in obese or diabetic patients and in patients who are likely to require prolonged mechanical ventilation postoperatively.