The anatomical SYNTAX score is advocated in both US and European guidelines to help establish the best revascularisation approach in patients with complex coronary artery disease.  The purpose of this study was to improve the SYNTAX score further by including prognostically important clinical variables, as opposed to the anatomical variables that are used for the current score.

The SYNTAX II score was developed by applying a Cox proportional hazards model to the results of the randomised all-comers SYNTAX trial.  In addition to the anatomical SYNTAX score, baseline features with strong associations to four-year mortality in either the CABG or PCI settings, or in both, were added.  Comparisons of 4-year mortality between CABG and PCI were then made for each patient.  External validation was done in the multinational all-comers DELTA registry (n=2891).

The eight predictors of the SYNTAX II score were: anatomical SYNTAX score, age, creatinine clearance, left ventricular ejection fraction (LVEF), presence of unprotected left main coronary artery (ULMCA) disease, peripheral vascular disease, female sex, and chronic obstructive pulmonary disease (COPD).  The SYNTAX II score significantly predicted a difference in 4-year mortality between patients undergoing CABG and those undergoing PCI; of note, the presence of diabetes was not important for decision making between CABG and PCI.  The concordance indices for internal (SYNTAX trial) and external (DELTA registry) validation were substantially higher than for the anatomical SYNTAX score alone.

Conclusions:

By combining clinical and anatomical predictors, the SYNTAX II score can provide accurate prediction of 4-year mortality from complex coronary artery disease, and guide decision making between CABG and PCI better than the original anatomical SYNTAX score.

• Farooq V, van Klaverern D, Steyerberg EW et al.  Anatomical and clinical characteristics to guide decision making between coronary artery bypass surgery and percutaneous coronary intervention for individual patients: development and vvalidation of SYNTAX score II.  Lancet 2013;381:639-50.