BACKGROUND: Little is known regarding intravascular ultrasound (IVUS) criteria to determine the functional severity of coronary stenosis. Recently, fractional flow reserve (FFR) has emerged as a lesion-specific index of the functional severity of a coronary stenosis that is independent of systemic hemodynamic variability. The present study was undertaken to determine the IVUS parameters for the physiological severity of coronary stenosis. METHODS AND RESULTS: Fifty-one lesions in 42 patients were evaluated by means of quantitative coronary angiogram, IVUS, and intracoronary pressure measurements. The FFR was calculated as the ratio of the distal coronary pressure divided by the proximal coronary pressure under hyperemia. We considered a value of the FFR 0.6 (sensitivity, 92.0%; specificity, 88.5%). The combination of both criteria (MLA <3.0 mm(2) and area stenosis <0.6) without exception met a value of the FFR <0.75. CONCLUSIONS: Anatomic parameters obtained by IVUS showed a significant correlation to the FFR values. The present study demonstrated that the combination of the MLA and area stenosis measured by IVUS can be an anatomic predictor for the physiological impact of coronary epicardial stenosis.
Takagi et al. (1999) studied this question.