What is the role of FFR 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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Myocardial FFR has been used as an index of functional severity of coronary artery stenosis. FFR represents the fraction of the normal maximal coronary flow that can be achieved in an artery in which flow is restricted by a coronary stenosis. The concept of FFR is based on the observation that myocardial perfusion is entirely pressure dependent during maximal hyperemia.

Maximal blood flow in the presence of a stenosis is therefore determined by the driving pressure distal (Pd) to the stenosis, whereas the theoretical normal maximal blood flow is determined by the pressure proximal (Pp) to the stenosis. FFR is calculated during maximal hyperemia (obtained with adenosine or papaverine) as FFR = Pd/Pp. FFR less than 0.75 is typically associated with other objective evidence of myocardial ischemia. FFR is calculated from the ratio of the mean pressure distal to a coronary stenosis to the mean aortic pressure during maximal hyperemia. If the FFR is less than 0.75, sensitivity is at least 80% and specificity is at least 85% for the presence of ischemia on noninvasive stress testing.

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