New set of intravascular ultrasound-derived anatomic criteria for defining functionally significant stenoses in small coronary arteries (results from Intravascular Ultrasound Diagnostic Evaluation of Atherosclerosis in Singapore [IDEAS] study).

We sought to determine the intravascular ultrasound-derived anatomic criteria for functionally significant lesions in small coronary arteries with a reference segment diameter <3 mm. A fractional flow reserve (FFR) of <0.75, as determined by pressure wire using high-dose (100 to 150 microg) intracoronary adenosine, was used as the reference standard for functional significance. For the 94 patients/lesions involved in the present study, the average reference vessel diameter was 2.72 mm. The FFR was <0.75 in 38 patients (40.4%) and > or =0.75 in 56 patients (59.6%). Logistic regression analysis identified the minimal lumen area, plaque burden, and lesion length as the 3 most important determinants of the FFR. Using classification and regression tree analysis, the best cutoff values for these determinants to discriminate a FFR of <0.75 versus > or =0.75 were a minimal lumen area of < or =2.0 mm(2) (sensitivity 82.35%, specificity 80.77%), plaque burden of > or =80% (sensitivity 87.9%, specificity 78.9%), and lesion length of > or =20 mm (sensitivity 63.6%, specificity 78.9%). A significant increase was found in the area under the receiver operating characteristic curve of the combined parameters (minimal lumen area plus plaque burden plus lesion length) compared to the plaque burden (p = 0.014) and other individual parameters (p <0.001). In conclusion, we found that intravascular ultrasound-derived anatomic criteria are able to predict the functional significance of intermediate lesions in small coronary arteries. A minimal lumen area of < or =2.0 mm(2), plaque burden of > or =80%, and lesion length of > or =20 mm predicted a FFR of <0.75 with good sensitivity and specificity.