FFR Guidance Remains Safe, Valuable in More Complex Disease
With the increasing availability of invasive diagnostic tools to improve lesion assessment, a didactic symposium at TCT 2015 was dedicated to discussion on the use of fractional flow reserve (FFR) measurement to guide management in patients with non-ST-segment elevation myocardial infarction and left main disease.
Colin Berry, BSc, MBChB, PhD, of the University of
Glasgow, in Glasgow, Scotland, reported findings from the FAMOUS–NSTEMI trial,
a randomized controlled trial study of 350 NSTEMI patients (mean age, 62 years;
74% male) with multiple lesions of ≥ 30% severity which were amenable to revascularization.
FFR findings were measured in both groups but disclosed to the operator in the
FFR-guided group (n = 176) and not in the standard angiography-guided group
(n = 174).
Berry noted that the proportion of patients treated initially by medical therapy was higher in the FFR-guided group than in the angiography-guided group; patients with an FFR ≤ 0.80 were directed to revascularization via PCI or CABG and those > 0.80 were treated with medical therapy.
“In addition [to FAMOUS-NSTEMI], the DANAMI-3 PRIMULTI trial was strongly supportive of the safety and potential efficacy of FFR-guided management of non-culprit lesions in STEMI patients,” Berry said.
In subset data from the DANAMI-3 PRIMULTI trial, 627 patients with multivessel disease were further randomized to receive either no additional PCI (n = 313) or FFR-guided complete revascularization prior to discharge (n = 314). At 1 year, FFR-guided complete revascularization reduced the primary endpoint of all-cause death, reinfarction and repeat revascularization compared with infarct-related artery PCI. Overall, Berry said that he would recommend use of FFR readings for NSTEMI non-culprit lesions, but uncertainty remains regarding its use in culprit lesions. Among STEMI patients, FFR levels could be used to guide management for non-culprit lesions but not those in the culprit artery, he added.
Fellow presenter William F. Fearon, MD, of Stanford University Medical Center, Calif., agreed that using FFR to guide revascularization is a safe approach in patients with left main disease.
In a meta-analysis of randomized controlled trials published in Catheterization and Cardiovascular Interventions, researchers examined outcomes among 525 patients with left main disease who underwent revascularization or medical therapy based on FFR. Fearon noted that “deferral for revascularization based on FFR was very safe; cardiac death rate tended to be lower compared to those underwent revascularization, and the MI rate was similar, too.”
However, Fearon noted some limitations to FFR, particularly associated with downstream stenosis in left main patients.
He cited a study published in JACC: Cardiovascular Interventions which assessed the true FFR of the left main coronary artery against the apparent FFR measured in the presence of stenosis in 91 paired measurements obtained from 24 patients. Results showed the true FFR was significantly lower than the apparent FFR (0.81 ± 0.08 vs. 0.83 ± 0.08, P < 0.001), which “was significant but not as great a difference as previously thought.” Fearon said that in all cases, when the apparent FFR was > 0.85, the true FFR was > 0.80.
“I think FFR could be useful, especially if you are interested in doing a single-stent crossover technique from a left main to the [left anterior descending], and you want to get a sense of the ostium of the circumflex and how involved it is with the disease,” Fearon said. “However, I think IVUS gives us a little more information, providing us with lesion length, vessel size, and the characteristics of the left main disease, which might affect our approach.”
Fearon noted that if cardiologists are attempting to determine whether left main disease is significant, FFR would represent a valuable assessment; however, when considering intervention strategies, IVUS can provide more information. Likewise, following intervention, Fearon said IVUS, in most cases, provides significantly more information than FFR.
- Berry reports receiving speakers bureau fees from AstraZeneca and St. Jude Medical and having institutional agreements with St. Jude Medical and University of Glasgow.
- Fearon reports receiving grant/research support from Acist Medical Systems, St. Jude Medical and Medtronic and consultant/honoraria fees from Medtronic.