OCT Shows Modest Ability to Identify Hemodynamically Severe Lesions

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Optical coherence tomography (OCT) exhibits moderate diagnostic efficiency in identifying functionally significant coronary lesions as established by fractional flow reserve (FFR), with a slight edge over intravascular ultrasound (IVUS) in small vessels, according to a study published in the March 20, 2012, issue of the Journal of the American College of Cardiology.

Researchers led by Nieve Gonzalo, MD, PhD, of Hospital Clínico San Carlos (Madrid, Spain), assessed the diagnostic efficiency of OCT in identifying hemodynamically severe coronary stenoses as determined by FFR in 56 patients with  lesions (n = 61) of intermediate angiographic severity. In a subgroup of 47 cases, OCT also was compared with IVUS.

In the overall cohort, OCT showed moderate diagnostic efficiency (area under the curve [AUC] 0.74; 95% CI 0.61- 0.84), with a sensitivity of 82% and specificity of 63% and an optimal cutoff value of 1.95 mm2.

For the group that received both IVUS and OCT imaging, there were no significant differences in diagnostic efficiency. IVUS had a sensitivity of 67% and specificity of 65% with an optimal cutoff value of 2.36 mm2. However, OCT was slightly more efficient than IVUS in assessing functional stenosis severity, especially in the subgroup of small vessels (n = 49; reference diameter < 3 mm; table 1).

Table 1. Diagnostic Efficiency of OCT vs. IVUS


(n = 61)

(n = 47)

P Value

Overall Cohort

AUC 0.70
(95% CI 0.55-0.83)

AUC 0.63
(95% CI 0.47-0.77)


Small Vessels

AUC 0.77
(95% CI 0.60-0.89)

AUC 0.63
(95% CI 0.46-0.78)


The AUC of the minimal lumen area (MLA) measured by OCT to predict an FFR ≤ 0.80 (hemodynamically severe stenoses) in vessels < 3 mm was 0.81 (95% CI: 0.67-0.90), with a best cutoff value of 1.62 mm2. On the other hand, the AUC of IVUS-derived MLA to predict such stenoses in these vessels was 0.63 (95% CI 0.46-0.78), with a best cutoff of 2.36 mm2.

According to the authors, OCT had a moderate ability to exclude functional impact when the MLA was greater than 1.95 mm2. In fact, 5 of 26 patients with an MLA > 1.95 mm2 had an FFR ≤ 0.80, and in all cases the stenoses were located in the left anterior descending coronary artery, “emphasizing the concept of the relation between the optimal MLA and the myocardial mass served by the vessel.” But the specificity and positive predictive value were 63% and 66%, respectively, which they say indicates the need for a more specific test to evaluate functional significance in situations where the OCT-derived MLA is less than 1.95 mm2, to avoid unnecessary interventions.

They also point out that the results apply only to stable stenoses “as the use of FFR in unstable lesions remains controversial.”

Role for OCT Still Undefined

In an editorial accompanying the study, Sotirios Tsimikas, MD, and Anthony N. DeMaria, MD, both of the University of California San Diego (La Jolla, CA), state the importance of determining what information can be obtained from OCT that is not available with current techniques.

The editorial notes that OCT provides high-resolution, well-defined images of intraluminal and endothelial/intimal structures, such as ruptured plaques, thrombi, spontaneous dissections, and angiographically vague coronary anatomy, such as ostial, bifurcation, and left main lesions. It is also able to identify thin-cap fibroatheromas, a key component of rupture-prone lesions However, it remains to be seen whether OCT will be able to discriminate lipid vs. nonlipid components such as the necrotic cores that are associated with high potential for plaque rupture, Drs. Tsimikas and DeMaria add.

“It also cannot fully measure plaque burden, particularly in larger arteries, or adequately assess remodeling due to depth of penetration issues, and may not be as amenable to testing pharmacological therapeutic interventions as IVUS,” they write.

Furthermore, the editorial continues, OCT’s usefulness “will ultimately rest on its ability to accurately identify the structures visualized. Importantly, the images must also result in improved clinical outcomes; for example, they should enhance stent deployment, prediction of late stent outcomes, and overall success of PCI.”

OCT Not an Acceptable Surrogate for FFR

William F. Fearon, MD, of Stanford Medical Center (Stanford, CA), said the study confirms that anatomic techniques like OCT and IVUS are “not particularly good” at assessing the hemodynamic significance of lesions compared with FFR.

The study also demonstrates that the ability of both imaging techniques to identify functionally important lesions is lessened in smaller vessels and in non-LAD lesions, he told TCTMD in a telephone interview.

“This paper reinforces the fact that using OCT to identify physiologically significant lesions may be slightly better than IVUS in terms of being able to get more accurate measurements of lumen size, but it’s still not an acceptable surrogate for FFR,” he said.

The apparent advantage of OCT over IVUS in small vessels is an interesting finding, Dr. Fearon said, “but we don’t know if it’s more accurate in measuring the lumen or if it just correlates better with FFR,” he added.

Like the editorial, he contended that more data are needed to help understand the clinical relevance of the clear images that OCT provides.

“My bias is to use FFR up front to help us decide if we need to stent, and then OCT or IVUS can be used as a terrific tool for optimizing the stenting procedure and ensuring that you have an excellent result,” Dr. Fearon said.


1. Gonzalo N, Escaned J, Alfonso F, et al. Morphometric assessment of coronary stenosis relevance with optical coherence tomography: A comparison with fractional flow reserve and intravascular ultrasound. J Am Coll Cardiol. 2012;59:1080-1089.

2. Tsimikas S, DeMaria AN. The clinical emergence of optical coherence tomography: Defining a role in intravascular imaging. J Am Coll Cardiol. 2012;59:1090-1092.



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  • Drs. Gonzalo and DeMaria report no relevant conflicts of interest.
  • Dr. Tsimikas reports serving as a consultant to Genzyme, ISIS, and Quest; receiving grants from Merck and Pfizer; and having an equity interest in and serving as a director for Atherotope.
  • Dr. Fearon reports receiving research support from St. Jude Medical.