Fractional flow reserve: Who needs the pressure wire?

Recently, the interest in coronary pressure measurements has been revited t hanks to technical innovations (the development of pressure-measuring angio plasty guidewire) and theoretical progress (the concept of pressure derived fractional flow reserve). Fractional flow reserve (FFR) is the ratio of ma ximal flow, in the myocardial region depending on a stenosis to maximal flo w in that same region if the stenosis were absent. with the development of pressure guidewires, fr fractional flow reserve can be calculated rapidly a nd safely in the diagnostic and interventional setting. It has been shown t hat pressure derived FFR can be used as a surrogate for a stress test for o n-line clinical decision making in the catheterization laboratory. Values < 0.75 are most often associated with exercise-inducible myocardial ischemia , while values > 0.75 exclude objective signs of ischemia during exercise. The accuracy of FFR for that purpose is approximately 95% and higher than t hat of any single noninvasive test taken alone. Of note, it has been shown that prognosis is favorable in patients in whom a planned angioplasty was d eferred on the basis of a myocardial fractional flow reserve > 0.75. After regular balloon angioplasty, the combination of a good angiographic result and a FFR > 0.90 is associated with an event rare during a 2-year follow-up , which is similar to that after stenting. After stent implantation, FFR sh ould normalize. A FFR < 0.94 after stent implantation appears to be as accu rate as intravascular ultrasound (IVUS) to detectstent, malposition. Thus, pressure derived FFR is a well-validated index of stenosis severity that ha s evolved from a physiological index to a clinical tool.