Bilateral internal thoracic artery grafting

Abstract

The effectiveness of the left internal mammary artery graft to the anterior descending coronary artery as a surgical strategy has been shown to improve the survival rate and decrease the risk of adverse cardiac events in patients undergoing coronary bypass surgery. These clinical benefits appear to be related to the superior short and long-term patency rates of the internal thoracic artery graft. Although the advantages of using of both internal thoracic arteries (ITA) for bypass grafting have taken longer to prove, recent results from multiple data sets now support these findings. The major advantage of bilateral ITA grafting appears to be improved survival rate, while the disadvantages of complex ITA grafting include the increased complexity of operation, and an increased risk of wound complications. While these short-term disadvantages have been mitigated in contemporary surgical practice, they have not eliminated. Bilateral ITA grafting should be considered the procedure of choice for patients undergoing coronary bypass surgery that have a predicted survival rate of longer than ten years.

Keywords: Coronary bypass surgery; bilateral internal thoracic artery grafting.

Figure 1

Comparison of survival and reoperation hazard function curves in the propensity-matched patients (both P<0.0001) [bilateral (BITA), n=1,989; single (SITA), n=4,147]. CABG, Coronary artery bypass grafting. Reproduced from Lytle BW, Blackstone EH, Loop FD, et al. Two internal thoracic and artery grafts are better than one. J Thorac Cardiovasc Surg 1999;117:855-72. Permission requested and currently under review

Figure 2

Comparison of matched pairs of patients receiving BITA and SITA grafts. The numbers of patients surviving at selected follow-up intervals are listed (P<0.001). Each symbol represents a death, and vertical bars depict the 68% confidence limits (equivalent to one standard error) of Kaplan-Meier estimates. Solid lines, enclosed within 68% confidence limits, are parametric estimates. BITA, bilateral internal thoracic artery; SITA, single internal thoracic artery. Reproduced from Lytle BW, Blackstone EG, Sabik JF, et al. The effect of bilateral internal thoracic artery grafting on survival during 20 postoperative years. Ann Thorac Surg 2004;78:2005-14. Permission requested and currently under review

Figure 3

Survival of matched pairs stratified by BITA and SITA according to normal or mildly impaired LVF (LVF normal/mild) or moderately or severely impaired left ventricular dysfunction (moderate/severe LVF). BITA, bilateral internal thoracic artery; LVF, left ventricular function; SITA, single internal thoracic artery. Reproduced from Lytle BW, Blackstone EG, Sabik JF, et al. The effect of bilateral internal thoracic artery grafting on survival during 20 postoperative years. Ann Thorac Surg 2004;78:2005-14. Permission requested and currently under review

Figure 4

Cumulative distribution of differences in survival between BITA and SITA for each patient in the study. The nonproportional hazard equations were solved twice for each patient, once as if the patient had SITA grafting and once as if the patient had BITA grafting. BITA, bilateral internal thoracic artery; SITA, single internal thoracic artery. Reproduced from Lytle BW, Blackstone EG, Sabik JF, et al. The effect of bilateral internal thoracic artery grafting on survival during 20 postoperative years. Ann Thorac Surg 2004;78:2005-14. Permission requested and currently under review