iFR identifies residual ischemia in nearly 25% of patients after PCI
NEW ORLEANS — After angiographically successful PCI, nearly 1 in 4 patients had residual ischemia as shown by instantaneous wave-free ratio measurement, according to the DEFINE-PCI study presented at the American College of Cardiology Scientific Session.
Allen Jeremias, MD, MSc, director of interventional cardiology research and associate director of the cardiac catheterization laboratory at St. Francis Hospital in Roslyn, New York, and colleagues conducted the study to determine the extent of residual ischemia, defined as iFR of 0.89 or less, on 500 patients (mean age, 66 years, 76% men) who underwent PCI and were determined by angiography to have no significant residual ischemia.
“We’ve known for many years that the coronary angiogram is not the best way to decide whether or not you should be treated [with PCI] and whether or not you have been treated satisfactorily,” Justin Davies, MBBS, PhD, interventional cardiologist at Hammersmith Hospital, Imperial College NHS Trust, London, told Cardiology Today’s Intervention. “We know from studies using pressure-wire technologies such as fractional flow reserve or iFR that it’s possible to identify people who would benefit from PCI, treat them, and leave the others alone. But we also know that you can’t use an angiogram reliably to identify who needs to be treated. Similarly, you can’t use an angiogram to identify if you have done a good job or not. Pilot studies have shown that in a proportion of patients, even if the angiogram looks good, there is a flow-limiting stenosis still there. So, we undertook this first-of-its kind prospective study looking to establish the frequency of flow-limiting lesions at the end of the case, and how often iFR can detect evidence of a focal stenosis.”
Davies is the inventor of iFR technology, which is marketed by Philips.
Average iFR gain from before PCI to after it was 0.24 (minimum, –0.07; maximum, 0.86).
Among the 480 patients who had angiographically successful PCI and qualified iFR pullbacks, 24% had residual ischemia, of which 81.6% were focal lesions and the rest were diffuse lesions, the researchers found.
“This is important because focal disease is something we can treat with balloons and stents, while diffuse disease is best treated with medical therapy,” Davies told Cardiology Today’s Intervention. “This shows us that there are patients who could have even better angioplasty than we’re giving them in the moment. We could give them better blood flow and potentially even better angina relief and symptom improvement, and hopefully outcomes will follow from that. This is a real opportunity to improve PCI further.”
Jeremias said in his presentation that “physiologic miss” occurred in 31.5% of focal lesions proximally and 30.1% of focal lesions distally, and that “if all residual focal lesions could be treated with additional PCI, the rate of significant ischemia could be theoretically reduced from 24% to 5%.”
The DEFINE-GPS study is now underway and will compare use of iFR, state-of-the-art imaging and artificial intelligence with use of angiograms to determine differences in angina relief, persistence of symptoms “and potentially even clinical behaviors and outcomes” after PCI, Davies said. – by Erik Swain
Jeremias A, et al. Featured Clinical Research II – Interventional. Presented at: American College of Cardiology Scientific Session; March 16-18, 2019; New Orleans.
Disclosures: The study was funded by Philips. Davies reports he invented iFR technology, which is marketed by Philips. Jeremias reports he received institutional educational grants from Abbott Vascular and Philips and consultant fees or honoraria from Abbott Vascular, AstraZeneca, Boston Scientific, Chiesi, Opsens and Philips.