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Improved survival with multiple left-sided bilateral internal thoracic artery grafts
S E Schmidt1, J W Jones, J I Thornby
1Baylor College of Medicine, Houston, Texas, USA.
Insights
Grafting both internal thoracic artery (ITA) bypass grafts to left-sided coronary arteries significantly improves long-term survival in patients undergoing bilateral ITA operations compared to traditional grafting. This strategy maximizes clinical benefits by targeting arteries supplying more left ventricular muscle.
Area of Science:
- Cardiovascular Surgery
- Cardiac Surgery Outcomes
- Coronary Artery Bypass Grafting
Background:
- Bilateral internal thoracic artery (ITA) bypass grafting is used to improve long-term outcomes, but optimal graft configuration is debated.
- Traditional bilateral ITA operations involve grafting to the left anterior descending and right coronary arteries.
- Previous studies have not compared outcomes based on specific coronary artery targets for bilateral ITA grafts.
Purpose of the Study:
- To compare the long-term clinical outcomes of patients undergoing bilateral ITA operations with different graft configurations.
- To determine if directing both ITA grafts to left-sided coronary arteries improves survival compared to traditional grafting.
Main Methods:
- A single-surgeon, 10-year experience of 498 consecutive bilateral ITA operations was analyzed.
- Patients were divided into two groups: Group I (traditional: left ITA to LAD, right ITA to RCA) and Group II (left ITA to circumflex, right ITA to LAD).
- Follow-up averaged 7.1 years with 94.2% completeness; survival was analyzed using Kaplan-Meier estimates and multivariate analysis.
Main Results:
- Operative morbidity and mortality were similar between groups; ITA conduit patency rates were also equivalent (91.7% vs 89.6%).
- Multivariate analysis revealed that ITA graft location significantly influenced survival (p=0.0288), independent of gender.
- Kaplan-Meier analysis showed significantly improved survival in Group II (both ITA grafts to left-sided arteries) compared to Group I (p=0.021), with curves diverging at 6 years.
Conclusions:
- Maximum long-term benefit from bilateral ITA operations is achieved by grafting to coronary arteries supplying more left ventricular muscle.
- Directing both ITA bypass grafts to left-sided coronary arteries represents an optimal configuration for enhanced patient survival.
- This strategy may lead to better functional status, although not statistically significant in this cohort.
Background:
Although conceptually sound, the use of multiple internal thoracic artery (ITA) bypass grafts to improve long-term clinical results remains controversial. This operation typically involves grafting the left ITA to the anterior descending artery and the right ITA to the right coronary artery. Past clinical studies of bilateral ITA operations have not examined comparative results associated with which coronary arteries received the ITA bypass grafts. Because grafting a superior conduit to an artery of lesser physiologic importance might reduce the clinical benefits, we compared the outcomes of patients receiving different configurations of bilateral ITA operations.
Methods:
The study group was 498 consecutive bilateral ITA operations, constituting the 10-year experience of a single surgeon. Follow-up averaged 7.1 years (mode 7.3 years), and was 94.2% complete. These patients were divided into two groups, 311 patients (group I) who underwent the traditional operation (left ITA to the left anterior descending artery, right ITA to the right coronary artery), and 187 patients (group II) who received revascularization of branches of the left coronary artery (left ITA to the circumflex system and right ITA to the left anterior descending artery).
Results:
The study groups were similar in age, severity of disease, number of bypassed arteries, ejection fraction, diabetes, hypertension, and duration of operation. There were more male patients in group II (91.4% versus 82.3%). A multivariate analysis showed that the location of ITA bypass grafts influenced survival independent of gender (p = 0.0288). Operative morbidity and mortality were similar between groups. Ninety-three patients had repeat angiography with equivalent patency rates of the ITA conduits (91.7% versus 89.6%; p = 0.67). The Kaplan-Meier actuarial survival estimate demonstrated a significant improvement in survival of patients in group II who received both ITA bypass grafts to left-sided arteries (p = 0.021), with the survival curves diverging at 6 years. More patients in group II were in New York Heart Association class I or II, but the difference was not statistically significant (94.6% versus 91.6%). Only 2 patients required reoperation.
Conclusions:
It appears that maximum long-term benefit from bilateral ITA operations is achieved by grafting the ITA conduits to coronary arteries that supply more left ventricular muscle.
