September 2nd, 2014
Fractional Flow Reserve Gains Support in Stable CAD and NSTEMI
Larry Husten, PHD
Two studies presented at the European Society of Cardiology meeting in Barcelona offered fresh support for fractional flow reserve (FFR), which has been slowly but surely gaining traction in the interventional cardiology community.
FFR in Patients with Stable CAD
Bernard De Bruyne presented 2-year results from the FAME 2 (Fractional flow reserve versus Angiography for Multivessel Evaluation 2) study (simultaneously published in the New England Journal of Medicine). FAME 2 was designed to find out whether PCI, with the help of FFR, can reduce the rate of hard endpoints in stable coronary artery disease (CAD) compared to medical therapy.
A total of 1220 patients with stable CAD underwent angiography with FFR. Of the group, 27% had no ischemic lesions on FFR (>0.80 pressure gradient) and were entered in a separate registry. Seventy-three percent had at least one stenosis with a pressure gradient of 0.80 or under and were randomized to PCI and medical therapy or medical therapy alone.
At two years the rate of the composite of death, nonfatal MI, or urgent revascularization was 8.1% in the PCI group compared with 19.5% in the medical therapy group (HR 0.39, CI 0.26-0.57, p<0.001). There were no significant differences in the rates of death and MI but the difference in urgent revascularization was large and highly significant (4% versus 16.3%, HR 0.23, CI 0.14-0.38, p<0.001).
After the first week, according to a landmark analysis, the rate of death and MI was significantly lower in the PCI group: 4.6% versus 8% (p=0.04). The investigators said that most MIs in the first week were likely related to procedures and were clinically unimportant, while events later on were more likely to be clinically significant.
FFR in Patients with NSTEMI
Although FFR has been gradually creating a role for itself in the catheterization lab, its use in acute coronary syndromes has not been previously studied. Results of FAMOUS NSTEMI (presented by Colin Berry and published simultaneously in the European Heart Journal) offer the first evidence in support of its use in this population.
A total of 350 NSTEMI patients referred for coronary angiography with at least one stenosis amenable to revascularization were randomized to receive treatment based on FFR or standard care with conventional visual assessment of stenosis severity. Twenty-two percent of patients in the FFR group changed treatment as a result of the FFR results. A total of 22.7% of FFR-guided patients and 13.2% of standard care patients received medical therapy alone. At one year 79% of patients in the FFR group and 86.8% of patients in the standard care group had been revascularized (p=0.054). There were two cases of coronary artery dissection that were attributed to the pressure wire.
Overall hospitals costs were about the same in each group. There was a trend toward more procedural MIs in the standard care group while other major adverse cardiac events that were not related to procedures appeared to occur more frequently in the FFR group. “Compared with the angiography-guided group, the increased adoption of medical therapy at the expense of revascularization in the FFR disclosure group was associated with similar overall health outcomes and quality of life at 1 year. Representing a balance of competing risks, the reduction in procedure-related MI events in the FFR group should be considered against the increase in spontaneous cardiac events during the follow-up.”
In an accompanying editorial, Bernard De Bruyne and Julien Adjedj write that “the message of the FAMOUS trial goes beyond the simple ‘less is more’. The data suggest a pivotal role of the cath lab in ACS, provided the procedure is comprehensive and of good quality… This approach provides all the elements for a complete diagnosis, optimal treatment, and thorough risk stratification. Moreover, this one-stop-shop renders the non-invasive diagnostic work-up largely obsolete.”
Commenting on the studies, Mark Creager, a cardiologist at the Brigham and Women’s Hospital and the president-elect oaf the American Heart Association, said that the studies help move the dial toward increased use of FFR in the cath lab, but they don’t provide an endorsement for universal usage of the technology. He emphasized the importance of clinical judgement in deciding whether patients with stable angina need to go to the cath lab. “Just as COURAGE doesn’t mean that no one with stable angina should get cathed, FAME doesn’t mean that everyone with stable angina should be cathed,” he said. “We’ve been doing FFR in selective cases in order to help decision analysis when we’re not sure.”