Even with compelling data suggesting the utility of imaging modalities, such as fractional flow reserve (FFR), intravascular
ultrasound (IVUS) and optical coherence tomography (OCT), to
guide percutaneous coronary intervention (PCI), the penetration of
these technologies in the United States remains low, said SCAI Past
President John McB. Hodgson, MD, FSCAI, at SCAI’s inaugural
Cardiovascular Professionals (CVP) Symposium at SCAI 2016.
“We continue to encourage people to [use these technologies],
but in the United States, the penetration for IVUS is about 18
percent of PCIs and the penetration for FFR, even after FAME, is
about 12 percent to 13 percent, so we have a long way to go,” said Dr.
Hodgson, who proceeded with an informative discussion about the
basics and best uses of FFR, IVUS and OCT.
For FFR, which uses pressure and hyperemia to assess individual
lesion impact on blood flow, Dr. Hodgson said it is best used to determine if fixing a lesion will improve flow, but is not meant to measure
“FFR is not about how bad is the lesion; it’s about [whether] this
lesion in this patient supplying this vascular distribution is impairing
hyperemic or exercise blood flow,” he said. “That is all it’s answering.
If you take exactly that same lesion and move it to a different vessel
that has twice the distribution you will get a different number.”
With IVUS, 20 to 80 MHz of ultrasound is used to visualize vessel
lumen and wall in real time. It provides good penetration, but less
resolution vs. OCT, according to Dr. Hodgson.
“Best uses of IVUS are optimizing stent placement; detecting
calcium, a horrible actor in terms of our ability to expand stents;
evaluation of angiographic ambiguity; and, now with the addition of
near infrared spectroscopy, finding lipid-rich, or so-called vulnerable,
plaques,” he said.
In place of ultrasound, OCT uses light to image vessel lumen and
wall surface in real time, providing less penetration but good resolution compared with IVUS. It is best used to define surface events, like
erosion and ulceration, optimizing stent placement and determining
thin cap fibroatheromas.
To illustrate how important selecting the right modality is, Dr.
Hodgson shared a study in which the rate of performing PCI was
significantly higher when the procedure was guided by IVUS vs. FFR
(91.5% v. 33.7%; P<.001).
“You will see atherosclerosis on the IVUS; that is OK. But it is not
to be used to determine when a lesion is flow limiting and needs to
be stented,” he said. “We use IVUS to rule out disease, not to rule in
In conclusion, Dr. Hodgson said, “My view is that revasculariza-
tion without these tools is insanity. It’s doing the same thing over and
over and expecting different results when we have very good data
now that selecting lesions by FFR and then guiding intervention by
IVUS or OCT will give the patient a better outcome.”
Still Not Widely Used
in United States