The ASLA Score: a CT angiographic index to predict functionally significant coronary stenoses in lesions with intermediate severity-diagnostic accuracy

Purpose To identify computed tomographic (CT) coronary indexes independently associated with a fractional flow reserve (FFR) of 0.8 or less, to derive a score that combines CT indexes most predictive of an FFR of 0.8 or less, and to evaluate the diagnostic accuracy of the score in predicting an FFR of 0.8 or less. Materials and Methods This retrospective study had institutional review board approval and waiver of the need to obtain informed consent. Consecutive patients who underwent CT coronary angiography and FFR assessment with one or more discrete lesion(s) of intermediate (30 -70 ) severity at CT were included. Quantitative CT measurements were performed by using dedicated software. The CT indexes evaluated included the following: plaque burden, minimal luminal area and diameter, stenosis diameter, area of stenosis, lesion length, remodeling index, plaque morphology, calcification severity, and the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) score, which approximates the size of the myocardium subtended by a lesion. By using covariates independently associated with an FFR of 0.8 or less, a score was determined on the basis of modified Akaike information criteria, and the C statistics of individual and combined indexes were compared. Results Eighty-five patients (mean age, 64.2 years; range, 48-88 years; 65.9 men; 124 lesions; 38 lesions with an FFR