Background Presence of myocardial ischemia is the most important prognostic factor in patients with coronary artery disease and is determined by both the lesion severity and the amount of myocardium supplied.
Objectives We performed this study to determine the optimal intravascular ultrasound (IVUS) criteria and to evaluate their accuracy for defining the functional significance of intermediate coronary stenoses in different locations of the coronary tree.
Methods This study was a multicenter, prospective study conducted in 4 Korean centers. Patients who had 30-70% de novo stenosis at the proximal or mid part of major epicardial coronary arteries with available IVUS and fractional flow reserve (FFR) were consecutively enrolled. Optimal IVUS criteria and their diagnostic accuracy for functionally significant stenoses (FFR <0.8) were assessed.
Results FFR was less than 0.8 in 88 lesions (33%). The determinants of FFR were minimum lumen area (MLA) and lesion location. The diagnostic accuracy of MLA was highly variable according to the location of lesions (Figure). The best cutoff value (BCV) of MLA to define the functional significance was 3.0mm² (AUC 0.81, 95% CI 0.68-0.91) for proximal left anterior descending artery (LAD) lesions and 2.75mm² for mid LAD lesions located before the 2nd diagonal branch (AUC 0.76, 95% CI 0.66-0.84). However, appropriate MLA to predict the functional significance of lesions could not be found in other segments.
Conclusions When IVUS parameters are used to determine the functional significance in patients with intermediate coronary artery stenoses, different criteria should be used according to lesion location. It should also be noted that variations in coronary anatomy can influence the diagnostic accuracy of these parameters.


Figure. Diagnostic Accuracy of Different Cutoff Points of Minimum Lumen Area to define the functional significance at Different Lesion Locations