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Discordant iFR, FFR results do not confer poor outcomes
SAN FRANCISCO — Among patients who had invasive coronary angiography and physiological assessments for at least one artery with intermediate coronary stenosis, having a normal fractional flow reserve value but an abnormal instantaneous wave-free ratio value or vice versa did not raise risk for poor outcomes, researchers reported.
Among patients whose lesions were deferred for revascularization, those who had low iFR and high FFR or vice versa had a similar rate of all-cause death, MI and revascularization at 5 years compared with patients who had high iFR and high FFR (adjusted HR for high FFR/low iFR vs. high FFR/high iFR = 1.32; 95% CI, 0.39-4.52; aHR for high iFR/low FFR vs. high FFR/high iFR = 1.1; 95% CI, 0.36-3.32), Seung Hun Lee, MD, PhD, cardiologist at Samsung Medical Center in Seoul, South Korea, said during a presentation at TCT 2019.
The low FFR/low iFR group had elevated risk for death/MI/revascularization compared with the high FFR/high iFR group (aHR = 2.46; 95% CI, 1.17-5.16), Lee said.
Low FFR was defined as 0.8 or less. Low iFR was defined as 0.89 or less.
The results were simultaneously published in JACC: Cardiovascular Interventions by Joo Myung Lee, MD, MPH, PhD, also a cardiologist at Samsung Medical Center, and colleagues.
The researchers classified 840 vessels in 596 patients from five centers in South Korea according to low or high FFR and iFR, and also analyzed 23 control patients to determine physiologic characteristics of discordant lesions.
“Discordance between iFR and FFR can be presented,” Lee said during his presentation. “In this study, we evaluated the physiologic characteristics and the mechanisms of discordance between iFR and FFR compared with normal control subjects, and tried to evaluate the long-term clinical outcomes of patients with discordant lesions.”
Compared with the low FFR/low iFR group, the low iFR/high FFR group had similar coronary flow reserve (P = .144), resistance reserve ratio (P = .241) and index of microcirculatory resistance (P = .476), whereas compared with the control group, the high iFR/low FFR group had similar coronary flow reserve (P = .16), resistance reserve ratio (P = .414) and index of microcirculatory resistance (P = .818), according to the researchers.
When all four FFR/iFR groups were compared, coronary flow reserve and resistance reserve ratio differed, but index of microcirculatory resistance did not, Lee said.
“The discordance between iFR and FFR is a natural phenomenon,” he said during the presentation. “The pattern of discordance is mostly determined by individual vasodilatory capacity. Lesions with discordance between iFR and FFR were not related to increased risk of events. More evidence is needed to find the best treatments for discordant lesions.”
In a related editorial published in JACC: Cardiovascular Interventions, Takayuki Warisawa, MD, sponsored researcher at Imperial College London, and Justin Davies, MBBS, PhD, interventional cardiologist at Hammersmith Hospital, Imperial College NHS Trust, London, wrote: “We are still lacking tools which can easily and reliably measure ischemia (rather than surrogates of ischemia), and tools which are able to simply assess the coronary microcirculation. These tools together with more clinical trial outcomes data will help to further shape revascularization decision-making in the next decade as we learn how to best treat diffuse and focal disease, and how to differentially manage patients presenting with myocardial edema following ACS and STEMI.” – by Erik Swain
References:
Lee SH, et al. Physiologic Guidance: Hyperemic, Basal and Angiographic Studies. Presented at: TCT Scientific Symposium; Sept. 25-29, 2019; San Francisco.
Lee SH, et al. JACC Cardiovasc Interv. 2019;doi:10.1016/j.jcin.2019.06.044.
Warisawa T, et al. JACC Cardiovasc Interv. 2019;doi:10.1016/j.jcin.2019.07.051.
Disclosures: Lee reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures. Davies reports he holds patents pertaining to the iFR technology, and he is a consultant for Philips and has received research grants and holds IP pertaining to Philips. Warisawa reports he received consultant fees from Abbott Vascular and Philips.