Fractional flow reserve is a new coronary hemo-dynamic para meter used to assess physiological impact of border line lesions in coronary artery disease. The calculation is simple
FFR is a terrible concept * for two reasons .
One , it never bothers about flow * across a lesion. It simply relies upon pressure drop. We know there is an intricate relationship between pressure and flow . Simple pressure drop can never be expected to translate into incremental flow in biological systems .
How crude it would be . . . to believe so ?
Two it ignores the morphology of the lesion . We know an eccentric soft lesion with a good distal FFR is live coronary explosive .
The FAME 1 and FAME 2 studies glorified FFR ! I differ in many ways .
Some of the observations made about FFR.
- FFR is to be done only in discrete , safe looking , intermediate lesions .(Do not ever attempt it in a eccentric lesion )
- FFR wire is a stiff ( stainless steel ) wire . Careful maneuvering is necessary . Lesion crossing and pull back FFR wire require some expertise.
- FFR / OCT combo, increase not only the fluroscopy time , this procedure can be more complex than the intended PCI .
- My colleagues tell me FFR measurements are not often reproducible .(I have little experience in this )
- Adenosine induced vasodilatation is not natural physiological model . Further it has a potential for a coronary steal if there is near critical lesion in contra lateral artery.
- There are many occasions FFR wire has caused dissection and subsequent stenting was necessary .(The very thing the cardiologist wanted to avoid !)
- Bifurcation lesion FFR measurement is prone for errors
- FFR in two tandem lesions cannot be assessed accurately
- Post PCI FFR is not practiced routinely in may centers the fear of status quo of FFR.
This post is not to defame the FFR as a concept . Just to make you think . . . how often , we are entrapped in a pseudo -intellectual game in the cath lab ! FFR as a tool , can still be valuable to assess coronary hemo-dynamics in a selected lesion population especially, discrete, single vessel , or left main disease with around 70 % narrowing . But never go with FFR alone .Consider the morphology , location of the lesion .
Finally do not forget , the good old EST can give a stiff fight for supremacy over FFR in terms of assessing physiological impact of a coronary stenosis (Especially in single vessel disease )