Does bilateral internal thoracic artery grafting increase long-term survival of diabetic patients?

Background. The purpose of the present study was to determine whether long-term survival in diabetic patients increased after bilateral internal thoracic artery (BITA) coronary bypass compared with matched patients with single internal thoracic artery (SITA) coronary bypass. Methods. The propensity for BITA was determined using logistic regression analysis and each BITA patient was matched with one SITA patient. Between January 1992 and March 2002, 980 matched diabetic patients (490 BITA versus 490 SITA) underwent coronary artery bypass surgery. Long-term survival data were obtained from the National Death Index (mean follow-up, 4.7 +/- 3.0 years). Groups were compared by Cox proportional hazard models and Kaplan-Meier survival plots. Results. Multivariate Cox regression analysis determined that BITA grafting had no significant effect on long-term survival (hazard ratio 0.89, 95% confidence interval: 0.69 to 1.14, p = 0.343). There were no differences in 30-day mortality (3.9% for BITA versus 3.7%, p = 0.999) and major postoperative complications except for length of stay (11.4 days for BITA versus 12.7 days, p < 0.001). Five-year survival rate was 79.9% in the BITA group and 75.7% in the SITA group (p = 0.252). There was no difference in 5-year survival rate between matched patients younger than 60 or from 70 to 79 years old. However, BITA patients aged 60 to 69 years had better 5-year survival rates (84.1% versus 71.0%, p = 0.0196), whereas the opposite was observed in patients aged more than 79 years (5-year survival for BITA 43.1% versus 70.0%, p = 0.016). Conclusions. Bilateral internal thoracic artery grafting had no significant effect on long-term survival for diabetic patients, but it may increase long-term survival in patients aged 60 to 69 years, whereas SITA grafting may be beneficial for patients more than 79 years old.