Optimal Intravascular Ultrasound Criteria and Their Accuracy for Defining the Functional Significance of Intermediate Coronary Stenoses of Different Locations

Abstract

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.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.Methods IVUS and fractional flow reserve (FFR) measurements were performed in 267 intermediate lesions located at the proximal or mid part of major epicardial coronary arteries. Optimal IVUS criteria and their diagnostic accuracy for functionally significant stenoses (FFR Ͻ0.8) were assessed.Results FFR was Ͻ0.8 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. The best cutoff value of MLA to define the functional significance was 3.0 mm 2 (area under the curve [AUC]: 0.81, 95% confidence interval [CI]: 0.68 to 0.91) for proximal left anterior descending artery (LAD) lesions and 2.75 mm 2 for mid-LAD lesions located before the second diagonal branch (AUC: 0.76, 95% CI: 0.66 to 0.84). However, the 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 of lesions in patients with intermediate coronary artery stenoses, different criteria should be used according to lesion location. In segments or vessels with anatomic variations, IVUS cannot be used for functional assessment of a stenosis.

What Is Ischemia and How Should This Be Defined Based on Modern Imaging?

“…57 The utility of IVUS in non-left main arteries is poor and lesion dependent. 51,52,[58][59][60] Some studies indicate that an IVUS MLA of < 4.0 mm 2 correlates well with an FFR < 0.75 and ischemia on SPECT 51 while others described that an MLA cut off is only useful in proximal and mid left anterior descending (LAD) lesions (MLA < 3.0 mm 2 and 2.75 mm 2 , respectively) and not appropriate for other lesions. 58 The limitation of IVUS in non-left main lesions is due to variability of physiologic significance on factors such as lesion location, length, eccentricity, and the prevalence of viable myocardium distal to the lesion.…”

“…51,52,[58][59][60] Some studies indicate that an IVUS MLA of < 4.0 mm 2 correlates well with an FFR < 0.75 and ischemia on SPECT 51 while others described that an MLA cut off is only useful in proximal and mid left anterior descending (LAD) lesions (MLA < 3.0 mm 2 and 2.75 mm 2 , respectively) and not appropriate for other lesions. 58 The limitation of IVUS in non-left main lesions is due to variability of physiologic significance on factors such as lesion location, length, eccentricity, and the prevalence of viable myocardium distal to the lesion. 51,52 In fact, a study by Nam et al demonstrated that while using both FFR and IVUS-guided PCI strategies for intermediate lesions led to favorable outcomes, those with IVUS-guided PCI had a higher rate of interventions performed than those with FFR-guided approach without any increase in adverse event rates in the FFR-guided group.…”

Technical Considerations and Practical Guidance for Intracoronary Optical Coherence Tomography

“…The basis for this approach comes from several studies that have shown moderate correlations between IVUS-derived MLA measurements and FFR values, with receiver operator characteristic (ROC) area under the curve (AUC) values ranging between 0.68 and 0.80. [5][6][7] Furthermore, an IVUS-based approach has been associated with good clinical outcomes and low subsequent adverse event rates. 8 OCT, similar to IVUS, can provide highly accurate and reproducible lumen area measurements.…”

“…However, given the presence of robust clinical evidence for physiologic lesion assessment with FFR, the use of OCT-derived anatomic criteria as a surrogate for functional significance should not be a standard approach. [5][6][7] In addition, the safety and efficacy of a strategy of performing PCI based on OCT-derived MLA less than or equal to 1.95 mm 2 and deferring PCI in the setting of an MLA greater than 1.95 mm 2 has not been determined. Larger and adequately powered studies are needed to define and validate optimal OCTderived MLA thresholds against FFR.…”

Clinical applications of fractional flow reserve in bifurcation lesions

“…Therefore, visual estimation of the bifurcation lesion by angiography can be inaccurate to predict the true anatomical or functional significance of the bifurcation lesion. Other invasive anatomical assessment tools such as intravascular ultrasound (IVUS) and optical coherence tomography can provide detailed anatomical information, but they still have limitations in assessment of the functional significance of a stenosis [21]–[24]. Previous studies showed that there can be discrepancies between anatomical parameters and functional significance in ostial lesions [20],[25].…”