AIMS: To prospectively validate the SYNTAX Score II and forecast the outcomes of 
the randomized Evaluation of the Xience Everolimus-Eluting Stent Versus Coronary 
Artery Bypass Surgery for Effectiveness of Left Main Revascularization (EXCEL) 
Trial.
METHODS AND RESULTS: Evaluation of the Xience Everolimus Eluting Stent vs. 
Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization 
is a prospective, randomized multicenter trial designed to establish the 
efficacy and safety of percutaneous coronary intervention (PCI) with the 
everolimus-eluting stent compared with coronary artery bypass graft (CABG) 
surgery in subjects with unprotected left-main coronary artery (ULMCA) disease 
and low-intermediate anatomical SYNTAX scores (<33). After completion of patient 
recruitment in EXCEL, the SYNTAX Score II was prospectively applied to predict 
4-year mortality in the CABG and PCI arms. The 95% prediction intervals (PIs) 
for mortality were computed using simulation with bootstrap resampling (10 000 
times). For the entire study cohort, the 4-year predicted mortalities were 8.5 
and 10.5% in the PCI and CABG arms, respectively [odds ratios (OR) 0.79; 95% PI 
0.43-1.50). In subjects with low (≤22) anatomical SYNTAX scores, the predicted 
OR was 0.69 (95% PI 0.34-1.45); in intermediate anatomical SYNTAX scores 
(23-32), the predicted OR was 0.93 (95% PI 0.53-1.62). Based on 4-year mortality 
predictions in EXCEL, clinical characteristics shifted long-term mortality 
predictions either in favour of PCI (older age, male gender and COPD) or CABG 
(younger age, lower creatinine clearance, female gender, reduced left 
ventricular ejection fraction).
CONCLUSION: The SYNTAX Score II indicates at least an equipoise for long-term 
mortality between CABG and PCI in subjects with ULMCA disease up to an 
intermediate anatomical complexity. Both anatomical and clinical characteristics 
had a clear impact on long-term mortality predictions and decision making 
between CABG and PCI.