Abstract
Although coronary artery calcium (CAC) is an established marker of coronary atherosclerosis,
whether it also reflects the physiological significance is unknown. This study aims
to evaluate if CAC could indicate physiological ischemia in intermediate stenosis
defined by an invasive fractional flow reserve (FFR). CAC score (CACS) derived from
either whole coronary arteries or individual arteries was measured by computed tomography
among patients with intermediate de novo lesions (percent diameter stenosis from 30%
to less than 70%). All stenoses were evaluated by invasive FFR; lesions with an FFR ≤ 0.80
were considered significant. We enrolled 119 patients with 143 lesions. Of these,
42 lesions (29.4%) demonstrated significant ischemia by FFR measurement. FFR values
had modest but significant correlations with CACS in individual arteries with intermediate
stenosis (r = − 0.290; p < 0.001). A receiver operating characteristic curve analysis showed that CACS of
individual arteries with intermediate stenosis had 71.4% sensitivity and 67.3% specificity
as a predictor of significant ischemia at a cut off value of 145.9. Multivariable
analysis showed that percent diameter stenosis and CACS in individual arteries with
intermediate stenosis were independent predictors for significant ischemia. By net
reclassification improvement analysis, CACS in individual arteries with intermediate
stenosis provided incremental prediction for significant ischemia over minimum lumen
diameter, percent diameter stenosis, and lesion length. CACS measured in each artery,
but not the total CACS, provides additional information as to whether an angiographically
intermediate stenosis within the artery is significant enough to cause myocardial
ischemia.
Keywords
coronary artery disease - intermediate stenosis - fractional flow reserve - CTCA -
coronary calcification
