Background: Previous studies have shown that there was a good correlation between fractional flow reserve (FFR) and minimum lumen area by intravascular ultrasound (IVUS). However, optimal cutoff value of IVUS parameter has not been evaluated in large number of lesions.
Methods: IVUS and FFR data were collected from 4 prospective registries (IPOP, PHANTOM, IDEAS and Wahsing Hosptical Center) from 3 different countries. Optimal IVUS criteria and their diagnostic accuracy for functionally significant stenoses (FFR ���0.8) were assessed.
Results: Up to now, 537 lesions (LAD 380 lesions, 71%) were analyzed (Final results of 750 lesions will be presented at the meeting). Angiographic minimumu lumen diameter, reference diameter and % diameter stenosis was 1.4짹0.5mm, 2.9짹0.6mm and 51.4짹12.9%, respectively. Mean FFR was 0.82짹0.10 and FFR���0.8 was in 187 lesions (34.8%). There was positive correlation between minimum lumen area (MLA) by IVUS and FFR (r=0.36, p<0.0001). The best cutoff value (BCV) of MLA to define the functional significance was 2.5mm2 (AUC 0.73, 95% CI 0.68-0.77). Positive and negative predictive values and diagnostic accuracy of this cutoff value were 50%, 78% and 67%, respectively. The diagnostic performance of MLA was better in large vessels (vessel diameter���3mm) (BCV 2.9mm2, AUC 0.81) than in small vessels (BCV 2.3mm2, AUC 0.66).
Conclusion: MLA by IVUS has low positive predictive value to predict the functional signficance of coronary stenosis. When MLA by IVUS is used to determine the functional significance of intermediate lesions, the amount of myocardium supplied by the target segment should be considered.