SAN FRANCISCO — Looks can be deceiving when evaluating stenoses for treatment with stenting, Dr. John M. Hodgson said at a cardiovascular imaging conference sponsored by the American College of Cardiology.
Not all stenoses detected on angiography are accompanied by ischemia, said Dr. Hodgson of St. Joseph's Hospital, Phoenix. “Two-thirds of the time, when a patient comes to the cath lab we do not have any functional imaging,” he said. “We do not know for sure that the patient has ischemia. And then we're left to interpret these fuzzy, two-dimensional angiograms.”
But the relatively new technology of measuring fractional flow reserve (FFR) during catheterization could help physicians make better informed decisions about revascularization and stenting.
In FFR, a pressure transducer is sent into the coronary artery, past the anatomic lesion. FFR is the transstenotic pressure gradient across a stenosis, measured at peak blood flow after the administration of a vasodilator (such as adenosine) and indexed for aortic driving pressure.
The result is a direct measurement of the influence of a specific lesion on blood flow. Only when the FFR is 0.75 or less, indicating a functional blockage of at least 25%, is stenting helpful.
The value of FFR was shown in a prospective randomized trial that indicated that not only is it safe to not revascularize stable lesions that don't limit blood flow more than 25%, but also that it provides better 24-month outcomes than does angiography (Circulation 2001;103:2928–34).