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iFR noninferior to FFR for revascularization in patients with stable angina, ACS
WASHINGTON — At 1 year, rates of MACE in patients who underwent revascularization guided by instantaneous wave-free ratio were comparable to those in patients who underwent revascularization guided by fractional flow reserve, according to data from two studies presented at the American College of Cardiology Scientific Sessions.
Both studies — DEFINE-FLAIR and IFR-SWEDEHEART — enrolled patients with stable angina or ACS who were indicated for physiologically guided assessment of a coronary lesion. The primary endpoint in both studies was a composite of all-cause mortality, nonfatal MI or unplanned revascularization within 12 months after the procedure.
DEFINE-FLAIR
In DEFINE-FLAIR, Justin Davies, MBBS, PhD, consultant cardiologist at Imperial College London, and colleagues randomly assigned 2,492 patients at 49 centers in 17 countries to undergo iFR-guided (n = 1,242) or FFR-guided revascularization (n = 1,250). The margin for noninferiority was 3.4 percentage points for the difference in risk.
Among patients who received iFR, 45% underwent PCI, 2% underwent CABG and treatment was deferred in 53%. Among those who received FFR, 50% underwent PCI, 3% underwent CABG and treatment was deferred in 47%.
The primary endpoint occurred in 6.79% of patients who underwent if-guided revascularization and 7.02% of those who underwent FFR-guided revascularization, with a difference of 0.2 percentage points (95% CI, 2.3 to 1.8; P < .001 for noninferiority; HR = 0.95; 95% CI, 0.68-1.33), according to the study results. There were no significant differences between the two groups for any of the individual components of the primary endpoint.
Event rates were also similar between patients in the iFR group and the FFR group in whom treatment was deferred, with MACE occurring in 4.7% of patients who received iFR and 6.14% of those who received FFR (P = 0.26).
However, the iFR group, compared with the FFR group, had considerably fewer procedural symptoms and clinical signs (3.1% vs. 30.8%; P < .001), which included dyspnea (1% vs. 20%), chest pain (1.5% vs. 7.2%), heart rhythm disturbances (0.2% vs. 4.8%), hypotension (0.3% vs. 1%) and serious adverse events such as bronchospasm or ventricular tachycardia (0.1% vs. 0.6%).
Procedure time was shorter by 4.5 minutes with iFR vs. FFR (40.5 vs. 45 minutes; P = .001).
“This study confirms that in patients with stable angina or ACS and coronary stenosis, iFR or FFR can safely guide coronary revascularization, and iFR improves procedural safety and reduces time,” Davies said.
iFR SWEDEHEART
iFR SWEDEHEART, conducted by Matthias Götberg, MD, PhD, of Lund University and Skane University Hospital in Sweden and colleagues, employed a registry-based randomized, controlled clinical trial design using data from the Swedish Coronary Angiography and Angioplasty Registry. A total of 2,037 patients were randomly assigned to iFR-guided revascularization (n = 1,012) or FFR-guided revascularization (n = 1,007). The margin for noninferiority was 3.2 percentage points.
Importantly, no patients were lost to follow-up, Götberg said.
Similar to results from DEFINE-FLAIR, rates of the primary endpoint were similar between the iFR group and the FFR group (6.7% vs. 6.1%), with a difference in event rates of 0.7 percentage points (95% CI, 1.5 to 2.8; P = .007 for noninferiority; HR = 1.12; 95% CI, 0.79-1.58).
There were also no significant differences between groups in secondary endpoints, including the individual components of the primary endpoint as well as target lesion revascularization, restenosis or stent thrombosis, at 12 months.
Procedural symptoms were significantly different, with 3% of the iFR group vs. 68.3% of the FFR group experiencing chest discomfort (P < .0001).
“iFR-SWEDEHEART demonstrates that iFR is a safe and feasible alternative to FFR in physiology-guided revascularization,” Götberg said during his presentation.
Looking ahead
In an editorial published in The New England Journal of Medicine, Deepak L. Bhatt, MD, MPH, Chief Medical Editor of Cardiology Today’s Intervention, commented on the potential implications of the findings from DEFINE-FLAIR and iFR-SWEDEHEART.
“In the treatment of stable coronary lesions, PCI is performed primarily for control of angina, and the use of if could help to guide decisions regarding PCI more rationally,” Bhatt, executive director of interventional cardiology programs at Brigham and Women’s Hospital and professor of medicine at Harvard Medical School, wrote.
“In the future, it would be an advance if noninvasive methods that provide simultaneous anatomical and physiological assessment of coronary lesions could supplant the need for invasive angiography. Nevertheless, there will always be patients in the catheterization laboratory who have a coronary stenosis of intermediate severity on angiography,” he wrote. “FFR has been the evidence-based standard for invasive evaluation of such lesions, but it now appears that if may be the new standard.” – by Melissa Foster
Reference:
Davies JE.
Götberg M. Late-Breaking Clinical Trials: Interventional. Presented at: American College of Cardiology Scientific Sessions; March 17-19, 2017; Washington, D.C.
Bhatt DL. N Engl J Med. 2017;doi:10.1056/NEJMe1702728.
Davies JE. N Engl J Med. 2017;doi:10.1056/NEJMe1702728.
Götberg M. N Engl J Med. 2017;doi:10.1056/NEJMoa1616540.
Disclosure: Davies reports financial ties with Medtronic and Volcano Corp. Götberg reports receiving consultant fees, honoraria and/or research grants from Boston Scientific, Medtronic and Volcano Corp. Bhatt reports receiving research grants, personal fees or other financial ties with Amarin, Amgen, AstraZeneca, Biotronik, Boston Scientific, Bristol-Myers Squibb, Cardax, Chiesi, Eisai, Eli Lilly, Ethicon, FlowCo, Forest Laboratories, Ironwood, Ischemix, Medtronic, Pfizer, PLx Pharma, Regado Biosciences, Roche, Sanofi Aventis, St. Jude Medical, Takeda and The Medicines Company.
Perspective
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It’s intriguing to have a technology that we now know is noninferior to FFR, which is the established therapy. There is going to be a higher adoption rate of iFR, especially since it promises improved patient comfort and shorter procedural time. As a result, we may see more people adopting physiologic testing of intermediate patients with this type of technology.
The issue is not whether we will convert to iFR. The issue is more basic: Can we make the technology easy enough that we’re going to be able to get more people to use it and perform more physiologic testing? With this easier technology, it may be easier to get more people to do it.
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These are two remarkable studies conducted with two multicenter groups that are both well respected in the field of coronary physiology. They effectively show us that using iFR-guided management vs. FFR-guided management performed similarly, and both studies met their endpoints for noninferiority.
Clinically, the ability to eliminate adenosine during functional assessment intuitively makes a lot of sense. We were encouraged by an adenosine-free iFR concept when it was introduced, but we needed more clinical outcomes data. These two trials now provide outcome evidence showing that if we opt to use iFR, we are going to be doing as good a job as FFR. Adenosine-related side effects can be significant for some patients, so it is nice that iFR avoids them as well as the cost of adenosine. An iFR option might now increase the use of coronary physiological assessment in stable CAD, which is underused in decision making for intermediately stenotic lesions.
With these two new studies, we will probably see a growth in iFR use, and that is a big deal because FFR has been established for more than 10 years.