The SYNTAX Score: A Grading System for Complex Coronary Artery Disease

The SYNTAX trial design paper described the rationale and protocol for a landmark randomized comparison of drug-eluting stent PCI versus coronary artery bypass grafting (CABG) in patients with de novo three-vessel or left main coronary artery disease, as well as the development of the SYNTAX score — a quantitative angiographic complexity score that became a cornerstone of revascularization strategy planning.

The SYNTAX score grades anatomical coronary complexity based on number, location, and characteristics of lesions, enabling risk stratification of patients before choosing between PCI and CABG. The design anticipated that a single trial could not definitively answer for all anatomical complexity levels, making the SYNTAX score the stratification tool for interpreting subgroup-specific recommendations.

The subsequent SYNTAX trial results (published 2009) showed that CABG was superior to PCI in three-vessel disease and high-complexity left main disease (SYNTAX score >33), while PCI and CABG produced similar outcomes in low-to-intermediate complexity disease. These results directly shaped guidelines and remain the foundation of Heart Team discussions about revascularization strategy for complex CAD.

The design paper is important because it introduced the SYNTAX score concept and defined the trial framework that produced one of the most cited trials in interventional cardiology.

We rate the evidence limited for this design paper specifically. Clinical significance is high because the SYNTAX trial and score are central to the management of complex multivessel CAD.