Effect of prior cardiac operations on survival after coronary artery bypass grafting

We examined a recent regional experience to determine the effect of a prior cardiac operation on short-term and midterm outcomes after coronary artery bypass grafting (CABG).

We identified 20,703 patients who underwent nonemergent CABG at 8 centers in northern New England from 2000 to 2008, of whom 818 (3.8%) had undergone prior cardiac operations. Prior CABG using a minimal or full sternotomy was considered a prior sternotomy. Survival data out to 4 years were obtained from a link with the Social Security Administration Death Index. Hazard ratios were estimated using a Cox proportional hazards regression model, and adjusted survival curves were estimated using inverse probability weighting. In a separate analysis, 1,182 patients were matched 1:1 by a patient's propensity for having undergone prior CABG.

Patients with prior sternotomies had a greater burden of comorbid diseases and increased acuity and had a greater likelihood of returning to the operating room for bleeding and low cardiac output failure. Prior sternotomy was associated with an increased risk of death out to 4 years for patients undergoing CABG, with an unmatched hazard ratio of 1.34 (95% confidence interval, 1.10 to 1.64) and a matched hazard ratio of 1.36 (95% confidence interval, 1.01 to 1.81).

Analyses of our recent regional experience with nonemergent CABG showed that a prior cardiac operation was associated with a nearly twofold increased hazard of death at up to 4 years of follow-up.