The effect of internal thoracic artery grafts on long-term clinical outcomes after coronary bypass surgery

Objectives We sought to compare long-term outcomes after coronary bypass surgery with and without an internal thoracic artery graft. Methods We analyzed clinical outcomes over a median follow-up of 6.7 years among 3,087 patients who received coronary bypass surgery as participants in one of 8 clinical trials comparing surgical intervention with angioplasty. We used 2 statistical methods (covariate adjustment and propensity score matching) to adjust for the nonrandomized selection of internal thoracic artery grafts. Results Internal thoracic artery grafting was associated with lower mortality, with hazard ratios of 0.77 (confidence interval, 0.62–0.97; P = .02) for covariate adjustment and 0.77 (confidence interval, 0.57–1.05; P = .10) for propensity score matching. The composite end point of death or myocardial infarction was reduced to a similar extent, with hazard ratios of 0.83 (confidence interval, 0.69–1.00; P = .05) for covariate adjustment to 0.78 (confidence interval, 0.61–1.00; P = .05) for propensity score matching. There was a trend toward less angina at 1 year, with odds ratios of 0.81 (confidence interval, 0.61–1.09; P = .16) in the covariate-adjusted model and 0.81 (confidence interval, 0.55–1.19; P = .28) in the propensity score–adjusted model. Conclusions Use of an internal thoracic artery graft during coronary bypass surgery seems to improve long-term clinical outcomes.