What is the role of CFR in the workup of coronary artery atherosclerosis?

Updated: Apr 09, 2021
  • Author: Sandy N Shah, DO, MBA, FACC, FACP, FACOI; Chief Editor: Yasmine S Ali, MD, MSCI, FACC, FACP  more...
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Relative CFR is calculated as follows: ([rCFR] = CFR target/CFR reference). Relative CFR involves Doppler coronary flow measurements of target and reference vessel CFR with a Doppler-tipped guidewire. In one report, El-Shafei et al found that, compared with patients who had negative stress-imaging study findings, patients who had positive stress-study findings showed more angiographically severe stenoses (74% +/- 13% vs 44% +/- 24%) with lower target CFRs (1.68 +/- 0.55 vs 2.46 +/- 0.74) and lower rCFRs (0.72 +/- 0.22 vs 1 +/- 0.26). [48]

Based on cut points (CFR >1.9; rCFR >0.75), compared with CFR, rCFR had similar agreement (kappa 0.54 vs 0.5), sensitivity (63% vs 71%), specificity (88% vs 83%), and positive predictive value (83% vs 81%) with myocardial perfusion tomography.

Although rCFR, as with CFR, correlates with stress myocardial perfusion imaging results, rCFR did not have significant incremental prognostic value over CFR alone for myocardial perfusion imaging. However, rCFR does provide additional information regarding the status of the microcirculation in patients with CAD and complements the CFR for lesion assessment.

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