Fractional Flow Reserve (FFR)

Fractional flow reserve (FFR) is a technique used in cardiac catheterization to measure pressure differences across a coronary artery stenosis. Fractional flow reserve (FFR) measurement involves determining the ratio between the maximum achievable blood flow in a diseased coronary artery and the theoretical maximum flow in a normal coronary artery to determine the likelihood that the stenosis impedes oxygen delivery to the heart muscle.


An FFR of 1.0 is widely accepted as normal. An FFR lower than 0.75-0.80 is generally considered to be associated with myocardial ischemia.

Indications for FFR measurement are as follows:

  • To determine the physiologic and hemodynamic significance of an angiographically intermediate coronary stenosis
  • To identify appropriate culprit lesion(s) in multivessel coronary artery disease (CAD)
  • To measure the functional importance of stenosis in the presence of distal collateral flow
  • To identify the precise location of a coronary lesion when the angiographic image is unclear


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FFR Basics: Performing an FFR Procedure - Mort Kern, MD
FFR Basics, Practice, Pitfalls - Mort Kern

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Prognostic Value of Fractional Flow Reserve