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

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Bilateral internal mammary artery grafting reverses the negative influence of gender on outcomes of coronary artery bypass grafting surgery.

OBJECTIVES: Coronary artery bypass grafting (CABG) has historically demonstrated higher hospital mortality in women compared with men. The influence of gender on long-term outcomes has not been clearly defined. METHODS: A retrospective analysis of 4584 consecutive CABG patients was conducted: 3647 men (1761 single internal mammary artery, [SIMA]; 1886 bilateral IMA, [BIMA]) and 937 women (608 SIMA and 329 BIMA). Propensity-score analysis and optimal matching algorithms were used to create matched groups for baseline risk factors between men and women (SIMA: 602 men and 602 women; BIMA: 328 men and 328 women). Cross-sectional follow-up (6 weeks to 32.1 years; mean 12.8 years) was 96.7% complete. RESULTS: Hospital mortality was higher in unmatched female vs male patients (SIMA 36/608; 5.9 vs 72/1761; 4.1%; BIMA 11/329; 3.3 vs 47/1886; 2.5%; P = 0.010). However, in the matched groups the increased hospital mortality for females approached statistical significance in the SIMA but not in the BIMA patients. (SIMA male 21/602, 3.5%; female 35/602, 5.8%; P = 0.055; BIMA male 12/328; 3.7%; female 11/328; 3.4%; P = 0.832). When propensity matched for baseline variables, the female SIMA patients experienced prolonged survival compared with their male counterparts. (male vs female, 20-year survival 17.0 ± 2.0 vs 26.4 ± 2.3%; median 10.4 vs 11.4; P = 0.043.) However, long-term survival between the matched male and the female BIMA patients was comparable (male vs female, 20-year survival 31.3 ± 3.6 vs 30.1 ± 3.6%; median 13.7 vs 13.7; P = 0.790). CONCLUSIONS: When liberally applied, BIMA grafting ameliorates both the increased perioperative mortality in female patients and the reduced long-term survival of male patients, effectively reversing the negative influence of gender on both short- and long-term outcomes of CABG surgery.

Bilateral internal mammary artery grafting enhances survival in diabetic patients: a 30-year follow-up of propensity score-matched cohorts.

BACKGROUND: The prevalence of diabetes mellitus is increasing at an unprecedented rate, affecting nearly 8% of the population. Previous studies have demonstrated a potential benefit for surgical over interventional revascularization in this group of patients. Similarly, studies have shown the superiority of bilateral internal mammary artery (BIMA) grafting over single internal mammary artery (SIMA) grafting in select populations. However, concerns about sternal wound infection have discouraged the use of BIMA grafting in diabetics. Therefore, we studied the long-term results of BIMA versus SIMA grafting in a large population of diabetic patients in whom BIMA grafting was broadly applied. METHODS AND RESULTS: Between February 1972 and May 1994, 1107 consecutive diabetic patients underwent coronary artery bypass grafting with either SIMA (n=646) or BIMA (n=461) grafting. Optimal matching with the propensity score was used to create matched SIMA (n=414) and BIMA (n=414) cohorts. Cross-sectional follow-up (6 weeks to 30.1 years; mean, 8.9 years) determined long-term survival. There was no difference in operative mortality, sternal wound infection, or total complications between matched SIMA and BIMA groups (operative mortality, 10 of 414 [2.4%] versus 13 of 414 [3.1%]; P=0.279; sternal wound infection, 7 of 414 [1.7%] versus 13 of 414 [3.1%]; P=0.179); total complications, 71 of 414 [17.1%] versus 71 of 414 [17.1%]; P=1.000). Late survival was significantly enhanced with the use of BIMA grafting (median survival: SIMA, 9.8 years versus BIMA, 13.1 years; P=0.001). Use of BIMA was found to be associated with late survival on Cox regression (P=0.003). CONCLUSION: Compared with SIMA grafting, BIMA grafting in propensity score-matched patients provides diabetics with enhanced survival without any increase in perioperative morbidity or mortality.

Bilateral internal thoracic artery grafting improves long-term survival in patients with reduced ejection fraction: a propensity-matched study with 30-year follow-up.

OBJECTIVE: Bilateral internal thoracic artery (BITA) grafting has been shown to improve long-term survival after coronary artery bypass grafting. However, there has been reluctance to use this technique in higher-risk patients. Patients with reduced ejection fraction (EF) have been shown to present a higher operative risk and reduced long-term survival. We studied the perioperative and long-term results of BITA versus single internal thoracic artery grafting (SITA) in a large population of patients with reduced EF in whom BITA grafting was broadly applied. METHODS: Between February 1972 and May 1994, 4537 consecutive patients in whom EF was recorded underwent SITA (2340) or BITA (2197) grafting. Prospectively collected clinical data recorded EF categorically as less than 0.30 (group I; n = 233), 0.30 to 0.50 (group II; n = 1256), or greater than 0.50 (group III; n = 3048). Multivariable analyses were performed to determine correlates of operative and late mortality. Optimal matching using propensity scoring was used to create matched SITA and BITA cohorts: group I, SITA and BITA, n = 87 each; group II, SITA and BITA, n = 448 each; group III, SITA and BITA, n = 1137 each. Equality of survival distribution was tested by the log-rank algorithm. RESULTS: There was no difference in operative mortality between matched SITA and BITA groups (group I: SITA vs BITA, 10.3% vs 6.9%, P = .418; group II: 4.7% vs 4.5%, P = .873; group III: 3.2% vs 2.0%, P = .086). SITA versus BITA was not a predictor of operative mortality on logistic regression analysis. There was no difference in freedom from any postoperative complication, including sternal wound infection, between matched SITA and BITA groups. Late survival was significantly enhanced with the use of BITA grafting in groups II and III (10- and 20-year survival, SITA vs BITA, in group II: 57.7% ± 0.3% and 19% ± 2.5% vs 62.0% ± 2.3% and 33.1% ± 3.4%, respectively, P = .016; and in group III: 67.1% ± 1.4% and 35.8% ± 1.7% vs 74.6% ± 1.3% and 38.1% ± 2.1%, respectively, P = .012). Likewise, choice of SITA versus BITA was a significant predictor of late mortality on Cox regression in both groups II (P < .007) and III (P < .001). CONCLUSIONS: Broadly applied BITA compared with SITA grafting in propensity-matched patients provides enhanced long-term survival with no increase in operative mortality or morbidity for patients with normal and reduced EF. The expanded use of BITA grafting should be seriously considered.

Location of the second internal mammary artery graft does not influence outcome of coronary artery bypass grafting.

BACKGROUND: Although the use of two internal mammary arteries (IMA) in coronary artery bypass graft surgery has been associated with improved patient survival and clinical status, the optimal use of the second IMA graft remains controversial. We, therefore, explored clinical outcomes in a large cohort of patients undergoing bilateral IMA grafting. METHODS: Between February 1972 and May 1994, 2,215 consecutive patients underwent bilateral IMA grafting. The second IMA was used to revascularize the left coronary system (LCS) in 1,479 and the right coronary system (RCS) in 736 patients. Propensity score optimal matching algorithm was used to create the matched LCS group (n=730) and RCS group (n=730). Cross-sectional follow-up (6 weeks to 32.1 years; mean 12.8; 96.7% complete) was performed. Multivariable analyses were performed to determine correlates of operative mortality and late mortality. Patient clinical status and Short Form-36 scores of late survivors were compared. RESULTS: There was no difference in either operative mortality or late survival between LCS and RCS patients, in either unmatched or matched groups. Operative mortality unmatched was LCS 38 of 1,479 (2.6%) versus RCS 20 of 736 (2.7%; p=0.837). For matched groups, it was LCS 13 of 730 (1.8%) versus RCS 20 of 736 (2.7%; p=0.284). Median survival in unmatched patients was LCS 15.8 years versus RCS 16.1 years (p=0.803); for matched patients, it was LCS 16.1 years versus RCS 16.1 years (p=0.671). Site of second IMA was not associated with either operative mortality or late survival on multivariable analysis. At follow-up, both groups demonstrated excellent clinical outcomes, with 98.4% of LCS patients and 96.8% of RCS patients in Canadian Cardiovascular Society class I or II, and no significant difference in either the physical (p=0.142) or mental (p=0.542) health summary scores on the Short Form-36. CONCLUSIONS: Use of two IMA grafts demonstrates excellent long-term results with no demonstrable difference in outcome between RCS and LCS patients.

Thirty-year follow-up defines survival benefit for second internal mammary artery in propensity-matched groups.

BACKGROUND: The value of the left internal mammary artery (LIMA) graft is well established. However, the incremental value of a second IMA graft is controversial. Despite reports of improved survival with bilateral IMA (BIMA) grafting, the Society of Thoracic Surgeons reports its use in 4% of coronary artery bypass graft operations. We report the influence of BIMA vs SIMA grafting on hospital and late mortality in comparable groups. METHODS: Retrospective review was conducted of 4584 consecutive isolated coronary artery bypass graft operations (2369 SIMA and 2215 BIMA) performed from 1972 to 1994. The influence of the second IMA was assessed by multivariate analyses of risk factors associated with hospital and late mortality and by propensity score analysis that compares patients with similar baseline characteristics for receiving a second IMA graft. All patients were monitored clinically to assess outcomes. RESULTS: Hospital mortality was 4.5% for SIMA vs 2.6% for BIMA patients (p = 0.001). When stratified by propensity score to undergo BIMA grafting, no difference in hospital mortality was found. Multivariate analyses showed SIMA grafting was significantly associated with late but not hospital mortality. Survival curves after 52,572 patient-years of follow-up (mean, 11.5 years; range, 6 weeks to 32 years) demonstrated improved long-term survival for BIMA vs SIMA patients in all quintiles except those with the greatest propensity for SIMA, wherein late survival was comparable between groups. In matched groups, survival favored BIMA patients (p = 0.001). CONCLUSIONS: BIMA grafting offers a long-term survival advantage over SIMA grafting in propensity-matched groups.