Percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) are both treatment options for coronary revascularisation in selected patients with stable coronary artery disease and ischaemia. Current European and US revascularisation guidelines indicate that the treatment selection depends on patient preferences, comorbidity, and complexity of coronary artery disease (CAD).1 ,2 Less complex single- or double-vessel coronary artery disease is preferably treated with PCI, where the level of acceptance is higher for PCI compared to CABG, whereas complex three-vessel disease is best treated with CABG, where the level of acceptance is higher for CABG.1 ,2

The number of diseased coronary vessels is not the only marker for CAD severity. The location of the lesions and their impact on blood flow,^w1 the degree of vessel stenosis, lesion classifications, and the diameter and calcification of the vessel are also important factors that affect the technical feasibility of performing PCI, and the prognosis. Considering these factors, there are different degrees of multivessel disease and the preferred revascularisation strategy may be different for specific lesion complexities. To assess this hypothesis the angiographic SYNTAX score was introduced.3

The SYNTAX score

The SYNTAX score was developed through expert consultation, and integrated previous angiographic scores that assessed lesion complexity: the American Heart Association (AHA) classification modified for the ARTS (Arterial Revascularization Therapy Study) study,^w2,w3 the Leaman score,^w4 the American College of Cardiology (ACC)/AHA lesions classification system,^w5 the total occlusion classification system,^w6 and the Duke and ICPS classification systems for bifurcation lesions.^w7 Subsequently the Medina classification of bifurcation lesions was introduced.^w8

The SYNTAX score was designed to quantify the complexity of left main (LM) or three-vessel disease. Using the openly accessible web based score calculator (http://www.syntaxscore.com) it is possible to calculate each patient's SYNTAX score by answering a series …