• Multivessel CAD requiring revascularization strategy decision
• PCI vs. CABG decision-making in complex coronary disease
• Risk stratification for adverse outcomes post-PCI
• Guide for invasive strategy planning and patient counselling

• Derived from SYNTAX trial (2009) comparing PCI vs. CABG
• Quantifies angiographic complexity independently of patient factors
• Predicts 1-year mortality, stroke, MI in PCI-treated patients
• Used in ACC/AHA guidelines to define complex CAD

• Each lesion scored independently using weighted algorithm
• Factors: bifurcations, calcification, thrombus, tortuosity, diffuseness
• Medina classification for bifurcation complexity
• Cumulative scoring across all significant lesions (≥50% stenosis)

• SYNTAX Score quantifies lesion morphology; SYNTAX II adds patient factors
• Score >32 traditionally recommended CABG over PCI, but evolving with modern techniques
• Left main stenosis markedly increases score and should prompt heart team consultation
• Does not account for LVEF, frailty, or patient preferences explicitly

• Subjective lesion assessment; inter-observer variability reported
• No accounting for left ventricular function in base score
• Derived pre-modern stent era; rotational atherectomy availability affects contemporary relevance
• Does not incorporate patient comorbidities (see SYNTAX II)

• PCI-first strategy reasonable for fit patients
• Single or staged procedures likely sufficient
• Standard dual-antiplatelet therapy and follow-up

• Heart team involvement strongly recommended
• Consider CABG if excellent graft targets; PCI if good left main reserve
• Patient values/preferences should heavily influence decision

• CABG strongly preferred in most guidelines
• PCI should be reserved for inoperable or very high-risk surgical candidates
• If PCI pursued: multistage approach, newest-generation stents, aggressive antiplatelet/anticoagulation
• Left main involvement almost always warrants CABG unless patient refusal

Developed collaboratively by interventional cardiologists led by Guy Sianos (Thoraxcentrum, Netherlands) for the SYNTAX trial. Published in 2005 as an angiographic grading system to standardize assessment of coronary complexity and guide left main and multivessel CAD treatment decisions.