SYNTAX Score Calculator
- SYNTAX Score: Explanation and Clinical Context
The SYNTAX Score is an angiographic tool to quantify the anatomical complexity of coronary artery disease by scoring each lesion with diameter stenosis of at least 50 percent in vessels of at least 1.5 millimeters. Each lesion is assigned a numeric value that reflects the myocardial territory at risk by a segment weight. The segment weight is multiplied by an occlusion multiplier and then adjusted by additive modifiers that reflect lesion complexity. Additive modifiers typically include lesion length greater than 20 millimeters, chronic total occlusion features including duration and stump morphology, bifurcation and trifurcation complexity with Medina patterns and branch angle, aorto ostial location, severe calcification, visible thrombus, and severe tortuosity. The global presence of diffuse small vessel disease is considered at the patient level and increases the overall complexity. The SYNTAX Score is intended to represent purely anatomic complexity and not clinical comorbidity. The original SYNTAX algorithm and tutorial define the detailed segment weights and the precise stepwise questions used in the official calculator and remain the definitive reference for exact scoring.
Clinical interpretation and utility
The SYNTAX Score is used to stratify anatomic complexity into categories commonly reported as low, intermediate, and high. These categories inform multidisciplinary Heart Team decisions about the relative advantages of percutaneous coronary intervention and coronary artery bypass grafting in patients with left main disease or multivessel disease. Patients with low scores may be appropriate candidates for either approach while those with high scores more often derive greater long term benefit from surgical revascularization in randomized trials. The SYNTAX Score is also independently associated with the risk of major adverse cardiac events after revascularization and may be used to compare disease complexity between cohorts and to quantify residual disease after an intervention. When the SYNTAX Score is used clinically it is recommended that the operator or core lab performing the score complete the official tutorial and, when possible, compare results to the official online calculator to ensure reproducibility.
Limitations and practical considerations
The SYNTAX Score is an anatomical score and does not include clinical variables such as age, left ventricular function, or comorbidities. For individualized mortality prediction and choice of revascularization strategy the SYNTAX Score II integrates clinical variables with the anatomical score and may provide better individualized guidance. Inter observer variability is described in the literature particularly for bifurcation and ostial lesions and reproducibility improves with training and use of the official tutorial. When precise trial level agreement or regulatory grade accuracy is required use of the official syntaxscore.org calculator or core lab reading is recommended.
Reference
Serruys P W, Onuma Y, et al. Percutaneous Coronary Intervention versus Coronary Artery Bypass Grafting for Severe Coronary Artery Disease. New England Journal of Medicine 2009.
Sianos G, Morel M A, et al. The SYNTAX Score. EuroIntervention 2005.
Official SYNTAX Score tutorial and calculator. SYNTAX Score Task Force. syntaxscore.org.
2018 ESC EACTS Guidelines on myocardial revascularization. European Heart Journal 2019.
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