SYNTAX Score Reproducibility and Variability Between Interventional Cardiologists, Core Laboratory Technicians, and Quantitative Coronary Measurements

Background-In the Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) trial, the SYNTAX score was useful in risk stratifying patients with complex coronary artery disease. The reproducibility of this score may affect its clinical utility. We therefore assessed SYNTAX score interobserver and intraobserver variability among a group of interventional cardiologists (ICs) and an experienced group of angiographic core laboratory (ACL) technicians. Methods and Results-After basic training from the SYNTAX score website, 3 ICs and 4 ACL technicians, each working independently, assessed the SYNTAX score of 30 multivessel disease angiograms. The ICs then underwent an intensive training session with ACL technicians, after which the SYNTAX score from 50 additional angiograms were assessed independently by both groups. Interobserver Fleiss kappa statistic values were determined. A third assessment was performed using quantitative coronary angiography (QCA). The ACL technician interobserver strength of agreement from both periods was substantial or greater (k=0.82; 95% CI [0.72, 1.00] and 0.84 [0.76, 1.00]) and not different than QCA. The IC interobserver agreement was initially estimated to be at least slight (k=0.33 [0.18, 0.44]), improving to substantial or greater after advanced training (k=0.76 [0.64, 1.00]). Despite advanced training, ICs underscored the number of lesions, bifurcations, and small-vessel disease (P<0.001), resulting in a lower score than ACL technicians (mean difference=7.5, P<0.001). Conclusions-Highly reproducible SYNTAX score measurements were quickly achieved by experienced ACL technicians. In contrast, agreement among ICs after the basic tutorial was initially poor but improved considerably after further training with the ACL, although differences still remained in interpretation of several lesion types. These findings have important implications for adoption of SYNTAX score methodology in routine practice and future clinical trials. (Circ Cardiovasc Interv. 2011; 4: 553-561.)