Complexity of coronary vasculature predicts outcome of surgery for left main disease

The SYNTAX score, a comprehensive angiographic scoring system, was recently developed as a tool for risk stratification during the SYNTAX trial (randomized trial comparing coronary artery bypass grafting with percutaneous coronary intervention). We applied the SYNTAX score in patients with left main coronary artery disease who underwent coronary artery bypass grafting to examine its role in predicting incidences of major adverse cardiac and cerebrovascular events (MACCE) within 30 days and 1 year.

One hundred forty-eight patients were studied. Their angiograms were scored according to the SYNTAX score. The MACCE-free survival curves were estimated by the Kaplan-Meier method. Univariate and multivariate analyses determined risk factors for MACCE. Performance of the SYNTAX score was studied with respect to discrimination by receiver-operating characteristic curves with their area under the curve (c-index). Classification and regression tree analysis was performed to identify the best outcome predictors and develop a risk stratification model.

Overall SYNTAX score ranged from 11 to 53 (mean, 24 +/- 9). At 30 days and 1 year, 15 (10%) and 19 (13%) patients experienced MACCE. Patients with a higher SYNTAX score had a significantly (p < 0.0001) poorer MACCE-free survival. In multivariate analysis, SYNTAX score, female sex, and incomplete revascularization were associated with a higher rate of MACCE in 30 days. The SYNTAX score was the single predictor for MACCE in 1 year. The c-index of the SYNTAX score was 0.88 for 30 days and 0.90 for 1 year, respectively. The SYNTAX score was the best single discriminator between patients with and those without MACCE, with a discrimination level of 36.5.

The SYNTAX score is the first coronary vasculature complexity score predictive for postoperative outcome in patients with left main coronary artery disease undergoing coronary artery bypass grafting. The outcomes of the ongoing SYNTAX trial will definitively define the role of the SYNTAX score in predicting short-term and long-term incidence of MACCE.