Coronary cross-sectional area stenosis severity determined by coronary CT highly correlated with coronary functional flow reserve: a pilot study

Abstract Fractional flow reserve (FFR) is the gold standard for assessing the physiological significance of coronary stenosis. We examined the potential correlation between digitally measured coronary cross-sectional area stenosis by coronary CT angiography, and the FFR. We analyzed 32 consecutive patients with stenoses who underwent invasive FFR determination. The cross-sectional area was assessed using 128-slice coronary detector-based spectral CT angiography. Power analysis revealed that the sample size enabled the detection of an area under the receiver operating characteristic (ROC) curve (AUC) of 0.90. FFR ≤ 0.8 and > 0.8 were defined as FFR-positive and FFR-negative, respectively. Intra- and inter-observer differences were negligible. AUC indicated that cross-sectional area reduction effectively discriminated between FFR-positive and FFR-negative cases, yielding a sensitivity of 0.882 and specificity of 0.933 at the cutoff of 50% area reduction, with an AUC of 0.976. Lesions with less than 45% cross-sectional area reduction on coronary CT angiography were not FFR-positive. When ROC analysis was conducted for lesion characteristics, AUC did not significantly improve. In conclusion, the coronary cross-sectional area stenosis severity from coronary CT angiography distinguished between FFR-positive and FFR-negative lesions with high accuracy. Area reduction on CT angiography is indicated to be clinically useful for predicting the FFR.