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Instantaneous Wave-free Ratio versus Fractional Flow Reserve to Guide PCI
Matthias Götberg1, Evald H Christiansen1, Ingibjörg J Gudmundsdottir1
1From the Department of Cardiology, Clinical Sciences, Lund University, Skåne University Hospital, Lund (M.G., T.T., M.N., D.E.), the Departments of Cardiology and Radiology, Helsingborg Hospital, Helsingborg (L.S., S.-E.O.), the Department of Cardiology, Karlstad Hospital, Karlstad (M.D., H.O.), the Uppsala Clinical Research Center (P.Ö.) and Department of Medical Sciences (S.K.J.), Uppsala University, Uppsala, the Department of Cardiology, Sahlgrenska University Gothenburg (E.O.), the Department of Cardiology, Faculty of Health, Örebro University, Örebro (F.C., O.F.), the Department of Cardiology, St. Göran Hospital (P.L.), the Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet (J.J.), and the Unit of Cardiology, Capio St. Görans Sjukhus (J.J.), Stockholm, the Departments of Cardiology and of Medical and Health Sciences, Linköping University, Linköping (D.V., D.H., G.P.), the Department of Internal Medicine, Västmanland Hospital Västerås, Västerås (A.K.), the Department of Cardiology, Kalmar County Hospital, and Linnaeus University, Faculty of Health and Life Sciences, Kalmar (J.C.), the Department of Medicine, Sundsvall Hospital, Sundsvall (J.J.), and the Department of Cardiology, Halmstad Hospital, Halmstad (A.-C.K.) - all in Sweden; the Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark (E.H.C., L.J., M.M.); and the Department of Cardiology, Reykjavik University Hospital, Reykjavik, Iceland (I.J.G.).
Insights
Instantaneous wave-free ratio (iFR) is noninferior to fractional flow reserve (FFR) for guiding revascularization in patients with coronary artery stenosis. Both strategies showed similar rates of major adverse cardiac events at 12 months.
Area of Science:
- Cardiology
- Interventional Cardiology
- Medical Devices
Background:
- The instantaneous wave-free ratio (iFR) is an index for assessing coronary artery stenosis severity.
- Previous small trials showed iFR has diagnostic accuracy similar to fractional flow reserve (FFR).
- Clinical outcome data for iFR use were previously lacking.
Purpose of the Study:
- To evaluate if iFR is noninferior to FFR regarding subsequent major adverse cardiac events.
- To compare clinical outcomes between iFR-guided and FFR-guided revascularization strategies.
Main Methods:
- A multicenter, randomized, controlled, open-label trial.
- 2037 patients with stable angina or acute coronary syndrome were randomized to iFR or FFR guided revascularization.
- The primary endpoint was a composite of death, nonfatal myocardial infarction, or unplanned revascularization within 12 months.
Main Results:
- The primary endpoint occurred in 6.7% of the iFR group and 6.1% of the FFR group (noninferiority met).
- No significant differences in myocardial infarction, target-lesion revascularization, restenosis, or stent thrombosis.
- More patients in the FFR group reported chest discomfort during the procedure.
Conclusions:
- iFR-guided revascularization is noninferior to FFR-guided revascularization for major adverse cardiac events.
- The findings support iFR as a viable alternative to FFR in guiding coronary revascularization.
- iFR guidance may reduce procedural discomfort for patients.
Background:
The instantaneous wave-free ratio (iFR) is an index used to assess the severity of coronary-artery stenosis. The index has been tested against fractional flow reserve (FFR) in small trials, and the two measures have been found to have similar diagnostic accuracy. However, studies of clinical outcomes associated with the use of iFR are lacking. We aimed to evaluate whether iFR is noninferior to FFR with respect to the rate of subsequent major adverse cardiac events.
Methods:
We conducted a multicenter, randomized, controlled, open-label clinical trial using the Swedish Coronary Angiography and Angioplasty Registry for enrollment. A total of 2037 participants with stable angina or an acute coronary syndrome who had an indication for physiologically guided assessment of coronary-artery stenosis were randomly assigned to undergo revascularization guided by either iFR or FFR. The primary end point was the rate of a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization within 12 months after the procedure.
Results:
A primary end-point event occurred in 68 of 1012 patients (6.7%) in the iFR group and in 61 of 1007 (6.1%) in the FFR group (difference in event rates, 0.7 percentage points; 95% confidence interval [CI], -1.5 to 2.8; P=0.007 for noninferiority; hazard ratio, 1.12; 95% CI, 0.79 to 1.58; P=0.53); the upper limit of the 95% confidence interval for the difference in event rates fell within the prespecified noninferiority margin of 3.2 percentage points. The results were similar among major subgroups. The rates of myocardial infarction, target-lesion revascularization, restenosis, and stent thrombosis did not differ significantly between the two groups. A significantly higher proportion of patients in the FFR group than in the iFR group reported chest discomfort during the procedure.
Conclusions:
Among patients with stable angina or an acute coronary syndrome, an iFR-guided revascularization strategy was noninferior to an FFR-guided revascularization strategy with respect to the rate of major adverse cardiac events at 12 months. (Funded by Philips Volcano; iFR SWEDEHEART ClinicalTrials.gov number, NCT02166736 .).
