Key result
iFR matches FFR for diagnostic agreement with HSR and is unimproved by adenosine.
Why the study?
To determine whether adenosine administration is required for the pressure-only assessment of coronary stenoses and whether it improves the diagnostic performance of iFR.
Does iFR provide equivalent diagnostic classification of coronary stenosis severity compared to FFR, and does adenosine administration improve its performance?
Observational (n=51)
Does iFR provide equivalent diagnostic classification of coronary stenosis severity compared to FFR, and does adenosine administration improve its performance?
iFR provides equivalent diagnostic classification of coronary stenosis severity compared to FFR, and its performance is not improved by adenosine administration, supporting its use as a vasodilator-free alternative.
Answers are grounded in this paper and cite their sources.
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“FFR is a valuable tool that helps doctors make treatment decisions, but certain barriers mean it isn't used as often as it might be. One of those barriers is the need to inject adenosine, which simulates how the heart behaves when the patient is exercising. Having to use adenosine increases the time, cost and complexity of the procedure, not to mention causing some discomfort for the patient. Our new approach could enable doctors to perform an accurate measurement without the use of drugs. We think this will have a big impact on clinical practice.”
“The results of the ADVISE trial indicate that intra-coronary resistance is naturally constant and minimized during the wave-free period. The instantaneous wave-Free Ratio (iFR) calculated over this period produces a drug-free index of stenosis severity that is comparable to FFR.”
May support adenosine-free iFR use in stenosis evaluation; leaves open need for larger outcome trials before practice change.
OBJECTIVES: This study sought to determine if adenosine administration is required for the pressure-only assessment of coronary stenoses. BACKGROUND: The instantaneous wave-free ratio (iFR) is a vasodilator-free pressure-only measure of the hemodynamic severity of a coronary stenosis comparable to fractional flow reserve (FFR) in diagnostic categorization. In this study, we used hyperemic stenosis resistance (HSR), a combined pressure-and-flow index, as an arbiter to determine when iFR and FFR disagree which index is most representative of the hemodynamic significance of the stenosis. We then test whether administering adenosine significantly improves diagnostic performance of iFR. METHODS: In 51 vessels, intracoronary pressure and flow velocity was measured distal to the stenosis at rest and during adenosine-mediated hyperemia. The iFR (at rest and during adenosine administration [iFRa]), FFR, HSR, baseline, and hyperemic microvascular resistance were calculated using automated algorithms. RESULTS: When iFR and FFR disagreed (4 cases, or 7.7% of the study population), HSR agreed with iFR in 50% of cases and with FFR in 50% of cases. Differences in magnitude of microvascular resistance did not influence diagnostic categorization; iFR, iFRa, and FFR had equally good diagnostic agreement with HSR (receiver-operating characteristic area under the curve 0.93 iFR vs. 0.94 iFRa and 0.96 FFR, p = 0.48). CONCLUSIONS: iFR and FFR had equivalent agreement with classification of coronary stenosis severity by HSR. Further reduction in resistance by the administration of adenosine did not improve diagnostic categorization, indicating that iFR can be used as an adenosine-free alternative to FFR.
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Sen et al. (2013) conducted an observational in Coronary stenoses (n=51). Instantaneous wave-free ratio (iFR) vs. Fractional flow reserve (FFR) was evaluated on Diagnostic agreement with hyperemic stenosis resistance (HSR) (AUC 0.93 vs 0.96, p=0.48). The instantaneous wave-free ratio (iFR) had equivalent diagnostic agreement with hyperemic stenosis resistance compared to FFR (AUC 0.93 vs 0.96, p=0.48), and was not improved by adenosine.
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