Fractional flow reserve (FFR) can be closely approximated using conventional coronary angiography and propriety software, according to the FAST-FFR study published online Sept. 24 in Circulation. The findings offer a potential route for more patients with suspected coronary artery disease (CAD) to receive functional assessment of lesions without the need for a guidewire or hyperemic agents.
Lead author William F. Fearon, MD, with Stanford University School of Medicine, and colleagues assessed 319 vessels from 301 patients with stable angina, unstable angina or non-ST elevation myocardial infarction. They performed both conventional angiography and pressure-wire based FFR and analyzed how well the angiography-derived FFR—using the proprietary software—matched the more invasive FFR measurements.
Fearon et al. found FFR calculated from coronary angiography (FFRangio) achieved a sensitivity and specificity of 94 percent and 91 percent, respectively, for classifying FFR in each vessel as “normal” or “abnormal.” FFR values above 0.80 were defined as normal, while values below that threshold were considered abnormal.
The method also achieved a diagnostic accuracy of 92 percent overall, including 87 percent in lesions near the normal/abnormal cutoff—those with FFR between 0.75 and 0.85.
“FFRangio may provide an easier and potentially faster method for performing physiology guided assessment of the overall coronary angiogram with similar accuracy to the reference standard, coronary pressure wire-based FFR,” Fearon and coauthors wrote. “This may translate into a greater percentage of patients undergoing physiologic guidance for revascularization decisions and ultimately improve long-term outcomes.”
Indeed, physiologic assessments of stenosis using FFR and other methods have been shown to lead to better patient outcomes than visual assessment, presumably due to more informed revascularization decisions for individuals with CAD. But uptake of guidewire-based FFR has lagged, Fearon and colleagues noted.
“FFR remains underutilized for a number of potential reasons, including the additional time needed to measure pressure wire-derived FFR, technical challenges and the small risk associated with maneuvering a pressure wire down a coronary artery, the added time to assess multiple vessels, issues with drift in the pressure wire reading, and the time, expense and associated side effects with some hyperemic agents necessary to measure FFR,” the authors wrote. “For all of these reasons, a technique for deriving FFR without the need of a pressure wire or hyperemic agent would be advantageous and could increase the adoption of physiology-guided revascularization.”
Two smaller, previous studies of FFRangio also demonstrated the diagnostic potential of this technique, the researchers noted, adding they feel further reassured by the 99 percent device success rate of FFRangio in their FAST-FFR study.
“A main potential advantage of the FFRangio system in comparison with pressure wire-derived FFR and the other angiographic techniques (including Quantitative Flow Ratio) for estimating FFR is that FFRangio provides a 3D reconstruction of the entire coronary tree with FFR values along each vessel,” Fearon et al. wrote. “This may improve the operator’s interpretation of the coronary stenosis and optimize revascularization strategies.”
Patients in the trial were 65 years old on average, 74 percent men and 42 percent of them presented with unstable symptoms.
Limitations of the study include its lack of data on the total time it took to calculate FFRangio and the exclusion of certain patient subsets such as those with left main disease, low ejection fraction and in-stent restenosis.
“Further studies comparing FFRangio-guided revascularization strategy and either angiography-guided revascularization or an FFR-guided revascularization strategy would help to further validate this new technique,” the authors said.
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.