PCI guided by quantitative flow ratio confers better 1-year outcomes vs. standard PCI
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PCI guided by quantitative flow ratio, a novel approach to estimate fractional flow reserve, was associated with lower rates of MACE at 1 year compared with PCI guided by angiography, according to results of the FAVOR III China trial.
In the randomized trial of 3,825 patients with angina or recent MI (mean age, 63 years; 29% women; 33.9% with diabetes; 63.5% with ACS), the primary endpoint of 1-year MACE, defined as all-cause death, MI or ischemia-driven revascularization, occurred in 5.8% of the quantitative flow ratio (QFR) group compared with 8.8% of the angiography group (difference, –3%; 95% CI, –4.7 to –1.4; HR = 0.65; 95% CI, 0.51-0.83; log-rank P = .0004), Bo Xu, MBBS, director of the catheterization laboratories at Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, said during a TCT 2021 press conference.
The major secondary endpoint, consisting of 1-year MACE excluding periprocedural MI, also favored the QFR group (3.1% vs. 4.8%; difference, –1.7; 95% CI, –2.9 to –0.5; HR = 0.64; 95% CI, 0.46-0.89; log-rank P = .0073), he said. The results were simultaneously published in The Lancet.
Xu said the results were driven by MI (HR = 0.59; 95% CI, 0.44-0.81; P = .0008) and ischemia-driven revascularization (HR = 0.64; 95% CI, 0.43-0.96; P = .031), noting that periprocedural MI (HR = 0.69; 95% CI, 0.49-0.97; P = .033) and nonprocedural MI (HR = 0.33; 95% CI, 0.16-0.68; P = .0025) favored the QFR group.
“The quantitative flow ratio, derived from 3-D coronary artery construction and flow dynamics computations from the angiogram, enables online estimation of [fractional flow reserve] without the use of pressure wires or pharmacological agents to induce hyperemia,” Xu said at the press conference.
All patients had at least one lesion with percent diameter stenosis 50% to 90% in a coronary artery with a reference vessel diameter of at least 2.5 mm. In those assigned to the QFR strategy, PCI was performed only if the QFR was 0.8 or less. Those assigned to the angiography strategy had PCI performed based on standard visual assessment.
“A QFR-guided vessel and lesion selection strategy improved 1-year clinical outcomes compared with standard angiography guidance in patients undergoing PCI,” Xu said at the press conference. “These benefits were due both to fewer procedural complications and superior long-term results compared with standard angiography guidance, with less myocardial infarctions and repeat revascularization procedures. The simplicity and the safety of QFR compared with wire-based physiological measurements should facilitate the adoption of physiologic lesion assessment into routine clinical practice.”
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This study represents the next stop on a journey that started with pressure wire-based techniques such as FFR for physiological assessment of coronary disease. This has progressed to FFR-CT and now to QFR. We are continuing to advance with less invasive techniques for assessing coronary artery blockages and determining how best to treat them. It has become less invasive and safer to assess coronary stenoses and select the right therapies to improve long-term outcomes. These newer techniques also require less time and less resources to make these assessments accurately.
QFR is used very little in the U.S. right now, but there has been growing interest in it. It will require an upgrading of technology in cath labs to perform QFR at the level seen in FAVOR III China. This can be done successfully, and QFR should be easier to implement than FFR-CT. It should also take less time to get up to speed with QFR than it took when we originally implemented FFR.
This is a very welcome, interesting and exciting study. We are going to see this technology come to the forefront. There is an ongoing trial in Europe to compare QFR with instantaneous wave-free ratio, which could further validate both of those technologies. If that happens, there will be an impetus to adopt this technology rapidly.
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Xu B, et al. Late-Breaking Clinical Trials Session I, in Collaboration with the Lancet. Presented at: TCT Scientific Symposium; Nov. 4-6, 2021; Orlando (hybrid meeting).
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