Preoperative prediction of long-term survival after coronary artery bypass grafting in patients with low left ventricular ejection fraction

Objective

We aimed to develop multivariable models of preoperative risk factors that predict long-term survival after coronary artery bypass grafting in patients with ejection fraction 25% or less.

Methods

We retrospectively evaluated 544 consecutive patients with ejection fraction 25% or less who underwent coronary artery bypass grafting from 1992 to 2002 at a single institution. Long-term survival data (mean follow-up 4.1 years) were obtained from the National Death Index. Multivariable Cox regression analysis was performed to construct a predictive score for long-term mortality. A split-sample approach was also used building a model on a training group (n = 360); this model was then tested on a separate validation group (n = 184).

Results

From the entire database, the predictive score was calculated according to the following equation: 0.430(if past congestive heart failure) + 0.049(age in years) + 0.507(if peripheral vascular disease) + 0.580(if emergency operation) + 0.366(if chronic obstructive pulmonary disease). The 5-year survivals of the predictive score quartiles were 82.3%, 78.2%, 65.5%, and 45.5% (P < .0001). The model based on the training group had four independent predictors for long-term mortality (the same as the listed equation except for past congestive heart failure). The 5-year survival rates of the quartiles were 90.1%, 75.4%, 64.3%, and 49.2% in the training group (P < .0001) and 77.4%, 71.2%, 65.8%, and 45.5% in the validation group (P = .0001).

Conclusion

Coronary artery bypass grafting in patients with severe ischemic cardiomyopathy achieves satisfactory midterm and long-term survival in selected patients. This new score, which is based on long-term data from a large number of patients, may aid clinicians in selecting therapeutic interventions for patients with ischemic cardiomyopathy.