To optimize outcomes for PCI procedures, new technologies have emerged to assist interventionalists with clinical decision making and patient selection. With fractional flow reserve (FFR) gaining more adoption since the release of the FAME trial in 2009, physicians are now exploring newer complimentary intravascular imaging technologies, such as optical coherence tomography (OCT). To assess the impact in U.S. cath labs, five interventional cardiologists discussed the practice management considerations.
Why & when to use?
FFR is a physiological index that determines the severity of blood flow blockages in the coronary arteries through a pressure wire technology measurement, and intravascular OCT provides high-resolution, cross sectional images of tissue in situ.
"There are distinct roles for these technologies," says Thomas Tu, MD, from Baptist Medical Associates in Louisville, Ky. "FFR is a hemodynamic assessment, and gathers information on the physiology of the coronary artery, whereas OCT is an anatomic assessment. As angiographers, we need both sets of information to understand lesions; the structural problems along with their functional significance."
FAME's Principal Investigator William F. Fearon, MD, from Stanford University Medical Center in Calif., says that the use of the pressure wire to measure FFR is the first step to determine whether or not a lesion is causing ischemia and therefore warrants PCI. "Then, I use anatomical techniques like OCT to optimize PCI: to guide decisions about stent length, vessel size, whether or not to use other techniques and to ensure that the stent is optimally well deployed, expanded and apposed without any edge dissection," he says.
OCT might find its largest niche in post-stent deployment. "You get excellent post-deployment data, and that's where the clinical data will probably lead us. OCT also provides a great deal of information on vulnerable plaque, which is intriguing, but we still need a better understanding of what to do with the information obtained," states Mark A. Turco, MD, from Washington Adventist Hospital in Takoma Park, Md.
Also, PCI has expanded to certain complex patient subsets, such as those with left main disease, in whom FFR may have a role. "It is vital to get a hemodynamic assessment for patients with left main disease. We also have excellent evidence now suggesting that in patients with left main disease that have FFRs greater than 0.75, they do not need to move forward with bypass surgery as these are hemodynamicaly insignificant despite what angiography might suggest," Turco says.
Likewise, Michael J. Rinaldi, MD, of Sanger Heart & Vascular Institute in Charlotte, N.C., says he employs OCT or other imaging technologies in at-risk patients, specifically where he perceives "higher risk factors for stent thrombosis or where the stenting results aren't perfect; overall about 30 percent of the time."
Others touted the image quality of OCT, but suggested its final role is yet to be determined. "Having better visual assessment is fantastic, and OCT is like high-definition compared with IVUS [intravascular ultrasound]," says Tu. "What we do with that information, the clinical significance, decision making based on that will come with experience.
Appropriate use: a driver of use
With the proliferation of FFR and otherintravascular imaging technologies, ACC President David R. Holmes, MD, from the Mayo Clinic questioned what would drive higher adoption. While there has been a "dramatic increase" in FFR utilization, he questions whether the increasing need for transparency will foster greater adoption.
"We are going to see an increase in the use of FFR due to the mounting oversight over our procedures," Turco points out. "Increased scrutiny on physicians performing appropriate procedures, and not over-stenting or over-intervening. While good clinical judgment is important, we are going to need a document with regards to FFR assessment to show we have legitimate evidence that a lesion is hemodynamically significant."
In particular, Maryland and Louisiana have undergone a fair amount of scrutiny due to alleged physician over-stenting. "It's going to be incumbent upon us to be fully transparent and follow the appropriate use criteria as proposed by the American College of Cardiology (ACC). We are going to need to prove how on board we are with guideline-driven medicine. These types of technologies will allow us to have the transparency that is needed," Turco