Bilateral internal thoracic artery use in patients with low ejection fraction: is there any additional long-term benefit?

OBJECTIVES: The use of bilateral internal thoracic arteries (BITA) has been associated with improved long-term outcomes following coronary artery bypass graft (CABG) surgery. The objective of this study was to evaluate the impact of BITA use on long-term survival among patients with low ejection fraction (EF) undergoing CABG.

METHODS: Between April 1991 and October 2011, 2035 consecutive patients underwent primary BITA grafting. Among them, there were 129 patients with left ventricular EF ≤40%. During the same time period, 1666 primary CABGs were performed using a single internal thoracic artery (SITA) in patients with EF ≤40%. A propensity score optimal matching algorithm was used to create the matched SITA and BITA groups (n = 111 in each group). Also, Cox regression multivariable analyses were performed to determine the independent risk factors for long-term mortality. The date of death was obtained from provincial vital statistics.

RESULTS: There was no difference in operative mortality between matched BITA and SITA (n = 2, 1.8% vs n = 1, 0.9%, respectively, P = 0.6) groups. The mean follow-up was 8.6 ± 5.1 and 7.7 ± 5.5 years for BITA and SITA groups, respectively (P = 0.2). Five-, 10- and 15-year survival rates were 93.7, 77.5 and 59.0% in the matched BITA patients vs 82.8, 68.1 and 65.2% in the matched SITA patients (P = 0.3). In multivariate analysis, the independent risk factors for late mortality among hospital survivors were: insulin-dependent diabetes [adjusted hazard ratio (HR): 3.4, 95% confidence interval (CI): 1.4-8.4, P = 0.008], perioperative intra-aortic balloon pump insertion (HR: 3.2, 95% CI: 1.5-6.9, P = 0.004), postoperative deep sternal wound infection (HR: 7.4, 95% CI: 2.2-24.1, P = 0.001) and neurological complications (HR: 3.5, 95% CI: 1.4-8.4, P = 0.006). Choice of BITA versus SITA was not an independent predictor of long-term mortality (P = 0.3).

CONCLUSIONS: The use of a second internal thoracic artery (ITA) does not prolong late survival in patients with low EF undergoing CABG compared with a propensity-matched group of SITA graft patients.