For coronary artery disease (CAD) patients undergoing PCI with drug-eluting stents (DES), routine measurement of fractional flow reserve (FFR) reduces rates of MI and death compared with standard angiography-guided PCI, according to a study published online May 26 in the Journal of the American College of Cardiology.
"FFR is an index of the physiologic significance of a coronary stenosis and is defined as maximal blood flow in a stenotic artery as a ratio to normal maximal flow,” the authors wrote. “It can be easily measured during coronary angiography by the ratio of distal coronary pressure measured with a coronary pressure guidewire to aortic pressure measured simultaneously with the guiding catheter during maximum hyperemia.”
Nico H.J. Pijls, MD, PhD, of the Catharina Hospital in Eindhoven, the Netherlands, and colleagues from the U.S. and other countries assessed the outcomes of the two-year FAME (Fractional Flow Reserve vs. Angiography in Multivessel Evaluation) clinical trial that enrolled 1,005 patients at 20 medical sites.
During the trial, patients were randomized to two groups: 496 patients to the angiography-guided PCI and 509 to the FFR-guided PCI.
FFR was measured with a coronary pressure guidewire (St. Jude Medical) and primary endpoints were major adverse cardiac events (MACE). The study also looked at cost-effectiveness and MI and death at two years.
According to the authors, overall 2,415 stents were placed—96.9 percent were DES—and more stents per patient were placed in the angiography-guided arm.
Results showed that rates of mortality after two-year follow-up were 3.8 percent in the angiography cohort and 2.6 percent in the FFR patient cohort. MI occurred in 9.9 percent of the angiography patients compared to 6.1 percent of the FFR patients.
At two years, the rates of death or MI were 12.9 percent in the angiography group compared to 8.4 percent in the FFR group. Additionally, incidence of revascularization occurred at a rate of 12.7 percent for the angiography group compared to 10.6 percent in the FFR group.
At the two-year mark, 22.4 percent of patients in the angiography-guided group experienced an incident of MACE compared to 17.9 percent of patients in the FFR group—overall rates of MACE declined by 30 percent.
“Thus, by systematically measuring FFR, the benefit of PCI can be maximized by accurately discriminating the lesions for which revascularization will provide the most benefit,” the authors wrote.
Potential limitations stemmed from the study being restricted to a two-year follow-up, the authors wrote. “Theoretically, unstented lesions in the FFR-guided group could progress and lead to future events beyond this time horizon."
They concluded: “Routine measurement of FFR as compared with PCI guided by angiography alone results in a significant reduction of the rate of mortality and myocardial infarction at two years, and supports the evolving paradigm of revascularization of ischemic lesions and medical treatment of non-ischemic ones."