Fractional Flow Reserve Facts Demonstrated safety, cost-effectiveness and clinical outcomes
Fractional Flow Reserve (FFR) is a lesion specific, physiological index determining the hemodynamic severity of intracoronary lesions. FFR can accurately identify lesions responsible for ischemia which, in many cases, would have been undetected or not correctly assessed by imaging technologies.
If an operator is uncertain about the ischemic significance of a stenosis, whether or not PPCI should be performed to the benefits of the patient, then flow (FFR) should be measured.Various clinical studies demonstrate that physiologic lesion assessment by FFR to guide routine PCI is superior to current angiography guided treatment.
Here are some of the landmark studies on Fractional Flow Reserves.
In 2007, evidence from the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial, questioned the necessity of PCI in patients with myocardial ischemia and substantial CAD.
After a mean follow-up of 4.6 years, the COURAGE study, which used angiography-guided PCI to study stable angina patients, showed no advantage of PCI over optimal medical therapy.
The use of PCI in addition to optimal medical therapy was associated with no significant difference in outcomes related to death, MI, stroke or rehospitalization due to acute coronary syndrome, compared with optimal medical therapy alone.
Boden WE, O’Rourke RA, Teo KK, et al. Optimal medical therapy with or without PCI for stable coronary disease. N Engl J Med. 2007;356(15):1503-16.
The DEFER study was undertaken in patients with stable chest pain and a functionally non-significant coronary stenosis to investigate if PCI of such stenosis is justified. This study indicated that the outcomes of patients referred for PTCA without objective proof of ischemia might vary depending on the severity of coronary stenoses detected by FFR. In patients with FFR scores ≥0.75, PTCA did not appear to improve patient outcomes compared to medical treatment alone. A 5-year follow-up of DEFER patients showed that these outcomes were maintained over time.
Five-year outcome after deferral of PCI of an intermediate coronary stenosis based on FFR 0.75 is excellent. The risk of cardiac death or myocardial infarction related to this stenosis is 1% per year and not decreased by stenting. (J Am Coll Cardiol 2007;49:2105–11) © 2007 by the American College of Cardiology Foundation – http://content.onlinejacc.org/article.aspx?articleid=1138219
The FAME study, Fractional Flow Reserve versus Angiography for Multivessel Evaluation, published in 2009, was designed to demonstrate whether patients with multivessel disease had better outcomes with FFR-guided PCI compared to angiography guided PCI.
A total of 1,005 patients with multivessel CAD, recruited from 20 centers in Europe and the U.S., were randomized to undergo angiography-guided PCI or FFR-guided PCI. Angiography-guided PCI involved the stenting of all indicated lesions, and FFR-guided PCI involved the stenting of lesions with FFR measurements ≤0.80. Patients in the angiography group had an average of 2.7 lesions per patient, which was similar to the average of 2.8 in the FFR group (P=0.34). However, the number of stents used per patient was significantly different between the two groups, with 2.7 used in the angiography group and 1.9 used in the FFR group (P<0.001).
At 1-year after stenting, a total of 91 patients (18.3 %) in the angiography group had experienced an event (death, nonfatal MI or repeat revascularization) compared with 67 patients (13.2 %) in the FFR group; these results were statistically significant (P=0.02). Tonino PA, De Bruyne B, Pijls NH, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention. N Engl J Med. 2009;360(3):213-24. – http://www.nejm.org/doi/full/10.1056/NEJMoa0807611
These follow-up data demonstrate the benefit of FFR measurement in patients with multivessel CAD. When FFR is used prior to PCI, patient outcomes are improved and unnecessary stenting is also prevented. Pijls NH, Fearon WF, Tonino PA, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention in patients with multivessel coronary artery disease: 2-year follow-up of the FAME (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation) study. J Am Coll Cardiol. 2010;56(3):177-84. – http://www.sciencedirect.com/science/article/pii/S0735109710016025
FAME II Study
The FAME 2, FFR-guided Percutaneous Coronary Intervention plus Medical Treatment vs. Medical Treatment Alone in Patients with Stable Coronary Artery Disease, study was designed to investigate the outcomes of stable angina patients receiving FFR-guided PCI compared with patients who received optimal medical therapy alone. (De Bruyne B, Pijls NH, Kalesan B, et al. Fractional flow reserve-guided PCI versus medical therapy in stable coronary disease. N Engl J Med. 2012;367(11):991-1001.) – http://www.nejm.org/doi/full/10.1056/NEJMoa1205361
FAME 2 was designed to assess whether FFR-guided PCI would result in improved outcomes for a composite endpoint of death, MI or urgent revascularization.
- Of 1,220 enrolled patients:
- 888 (73 %) patients with ≥1 lesion with an FFR score of
- 332 (27 %) patients in whom all stenoses had an FFR ≥0.80 received optimal medical therapy alone (registry group).
- Patients in the medical therapy group showed a significantly higher need for urgent revascularization, compared to patients in the FFR group (11.1 % vs. 1.6 %, P<0.001).
- Patients in the medical therapy group were more likely to have revascularizations triggered by MI or evidence of ischemia (P<0.001).
Recruitment for the FAME 2 study was halted in January 2012, when an independent Data and Safety Monitoring Board (DSMB) recommended early termination of the study. The preliminary results were considered so compelling that research was stopped so patients with FFR <0.80 randomized to optimal medical therapy only could also receive the benefits of PCI.
These data support the idea of treating patients with “Functionally Complete Revascularization.” With this approach, only ischemia inducing lesions require stenting. When used in patients indicated to receive PCI, FFR is the key to determining the right treatment for each patient.
FFR-guided treatment also produced a 14% cost reduction for the hospital after one year thanks to lower procedural costs, reduced numbers of follow-ups for major adverse cardiac events, and shorter hospital stay. When FFR was used in stenting decision, the number of stents was cut by 1/3 and positive outcomes also increased by 1/3, a startling result that leads to the conclusion that placing fewer stents and guiding those placed with FFR makes stenting about 33% more effective.