Mathematically Derived Criteria for Detecting Functionally Significant Stenoses Using Coronary Computed Tomographic Angiography-Based Myocardial Segmentation and Intravascular Ultrasound-Measured Minimal Lumen Area.

The lack of practical method for quantifying myocardial territories has made it difficult to link anatomic lesion morphology to the hemodynamic significance of coronary artery stenosis. The aim of this study was to develop and validate mathematically derived morphologic criteria for predicting fractional flow reserve (FFR) <0.80 using intravascular ultrasound (IVUS) parameters and a coronary artery-based myocardial segmentation (CAMS) of the affected myocardial territory. Coronary computed tomography angiography, IVUS, and FFR data were analyzed in 103 non-left main intermediate coronary artery lesions (30% to 80% of angiographic stenosis). Using CAMS method, the total left ventricular myocardial volume and the myocardial volume subtended by a stenotic coronary segment (Vsub) were assessed. The morphologic criteria for detecting an FFR <0.80 using the IVUS and CAMS parameters were mathematically derived. Overall, an IVUS-measured minimal lumen area (MLA) <2.79 mm(2) predicted an FFR <0.80 with sensitivity of 76%, specificity of 78%, positive predictive value of 71%, and negative predictive value of 82%. A Vsub/MLA(2) >4.04 best predicted an FFR <0.80 (sensitivity 88%, specificity 90%, positive predictive value 86%, and negative predictive value 92%, area under curve = 0.944). There was a significant difference in the areas under the curves between IVUS-MLA versus Vsub/MLA(2) (difference = 0.068, p = 0.005). Conversely, adjusting for body or vessel size did not improve the diagnostic accuracy.