The relative severity of a lesion is indicated using a score of 1 for 1-25% obstruction and doubling that number as the severity of obstruction progresses with each step in the 25-50-75-90-99-100% diameter reduction. Thus, the severity score for each lesion may range from 1 to 32. Furthermore, the score weighed according to the usual blood flow to the left ventricle in each vessel or vessel segment. A multiplying factor is applied to each lesion score based upon its location in the coronary tree, depending on the functional significance of the area supplied by that segment. If a segment is totally occluded or 99% stenosed and receiving collaterals, a collateral adjustment factor is used, and the adjustment is reduced by the extent of disease in the vessel that is the source of collaterals. The final score is the sum of all the lesion scores.

CCTA-derived SYNTAX score (CT-SYNTAX score) is a lesion-based grading tool to characterise the coronary vasculature with respect to the number of lesions and their functional impact, location, and complexity. Higher SYNTAX scores, indicative of more complex disease, are hypothesized to represent a bigger therapeutic challenge and to have potentially worse prognosis.

Frequency (%) of occurrence of high-risk plaque features (HU < 30, Remodelling Index > 1.1, napkin-ring sign & spotty calcium)

Patients are assigned a risk score between 0-100 based on former patient prognosis data. The score is an extension of the 3-vessel disease score. It also incorporates stenosis severity and calculates with left main stenosis and proximal left anterior descending stenosis. There is a significant difference between patients' cumulative survival for the different categories. Left main plaque with any additional moderate or severe stenosis indicates the worst outcome.