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FAVOR II trials: Positive outcomes for quantitative flow ratio
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Quantitative flow ratio was found to be accurate in diagnosing hemodynamically significant coronary stenosis and was superior to standard quantitative angiographic assessment for detection of stenosis requiring revascularization, according to two studies presented at TCT 2017.
The FAVOR II China and FAVOR II European-Japan studies evaluated different aspects of quantitative flow ratio, an angiography-based method for deriving fractional flow reserve without pressure wire or induction of hyperemia.
FAVOR II Europe-Japan
According to a presentation from Jelmer Westra, MS, research fellow at Aarhus University Hospital in Denmark, pressure wire measurements are the present gold standard for patients with angina pectoris, which is often costly and invasive, and in clinical practice, the decision to treat a stenosis is often based on angiographic evaluation.
“Quantitative flow ratio is a computational method for emulating pressure wire measurements that has showed good agreement with the current gold standard fractional flow reserve,” Westra said during his presentation. “Feasibility and precision of [quantitative flow ratio] are unknown when performed during coronary angiography and in a multicenter setting.”
Westra and colleagues conducted a prospective, observational study at 11 hospitals in Europe to evaluate the feasibility and precision of in-procedure quantitative flow ratio compared with standard quantitative angiographic assessment with FFR as standard treatment.
The primary endpoint of the study was sensitivity and specificity of quantitative flow ratio compared with 2-D quantitative coronary angiography.
According to the study, quantitative flow ratio had higher rates of sensitivity (88% vs. 46%; P < .001) and specificity (88% vs. 77%; P < .001) in comparison to 2-D quantitative coronary angiography.
“[Quantitative flow ratio] showed superior sensitivity and specificity for detection of functional significant lesions in comparison with [2-D quantitative coronary angiography] using FFR as reference standard,” Westra said in a press release from the Cardiovascular Research Foundation. “In addition, in-procedure [quantitative flow ratio] computation was feasible and was computed within the time of standard FFR measurements.”
FAVOR II China
A second trial, conducted between June and July 2017 at five centers in China, assessed the diagnostic accuracy of quantitative flow ratio in diagnosing hemodynamically significant coronary stenosis as defined by FFR.
According to a presentation by Bo Xu, MBBS, the prospective, multicenter study included patients aged at least 18 years who had stable and unstable angina. Patients were excluded if they had MI within 72 hours, severe HF, ostial lesions or main vessels with stenotic side branches downstream the interrogated lesion.
The researchers assessed quantitative flow ratio and quantitative coronary angiography both online in a masked fashion during coronary angiography and offline at an independent core laboratory.
The primary endpoint of the study was diagnostic accuracy of online quantitative flow ratio with FFR.
Patient-level and vessel-level diagnostic accuracy of quantitative flow ratio were 92.4% (95% CI, 88.9-95.1) and 92.7% (95% CI, 89.3-95.3), respectively, which were both higher than the prespecified target value (P < .001), according to Xu and colleagues.
The researchers also found higher sensitivity and specificity in identifying hemodynamically significant stenosis for quantitative flow ratio compared with quantitative coronary angiography (sensitivity: 94.6% vs. 62.5%; difference, 32%; P < .001; specificity: 91.7% vs. 58.1%; difference, 36.1%; P < .001).
The study results show that the positive predictive value was 85.5%, negative predictive value was 97.1%, positive likelihood ratio was 11.4 and negative likelihood ratio was 0.06.
Offline analysis indicated a high diagnostic accuracy of 93.3% for vessel-level quantitative flow ratio (95% CI, 90-95.7).
“The FAVOR II China study met its prespecified primary performance goal for the level of diagnostic accuracy of [quantitative flow ratio] in identifying hemodynamically significant coronary stenosis,” Xu said. “It demonstrates clinical utility of [quantitative flow ratio] for use in diagnostic catheterization laboratories, and [quantitative flow ratio] bears the potential of improving angiography-based identification of functionally significant stenosis during coronary angiography.” – by Dave Quaile
References:
Westra J. Late-Breaking Clinical Trials 2. Presented at: TCT Scientific Symposium; Oct. 29-Nov. 2, 2017; Denver.
Xu B, et al. J Am Coll Cardiol. 2017;doi:10.1016/j.jacc.2017.10.035.
Xu B. Late-Breaking Clinical Trials 2. Presented at: TCT Scientific Symposium; Oct. 29-Nov. 2, 2017; Denver.
Disclosures: The FAVOR II China study was funded by the National Key Research and Development Program of China, the Natural Science Foundation of China and the Pulse Medical Imaging Technology Co., Ltd. The FAVOR II Europe-Japan study was funded by Aarhus University Hospital, Skejby and participating institutions. Westra reports he receives grant and research support and consultant fees and honoraria from Medis Medical Imaging. Xu reports no relevant financial disclosures.