Fractional flow reserve (FFR) is an established invasive method for assessing the
physiological significance of coronary artery stenosis. Adenosine, an important endogenous
regulator of coronary blood flow during both stress and ischemia, is widely used to achieve
conditions of stable hyperemia required for measurement of FFR.
Studies in healthy volunteers and in patients with acute coronary syndrome (ACS) post
percutaneous coronary intervention (PCI) receiving ticagrelor revealed a differential
coronary blood flow velocity response during increasing doses of adenosine compared to
placebo or prasugrel treated subjects, respectively. It has also been demonstrated that
patients treated with ticagrelor have increased plasma adenosine levels. Therefore, it has
been hypothesized that the degree of hyperemia obtained with adenosine infusion may be
greater in patients on ticagrelor than that obtained in patients taking clopidogrel or
prasugrel. If this proves to be true, it would lead to a lower FFR value with possible
important clinical implications in ticagrelor receiving patients in need for FFR measurement.
This is a prospective, single center, randomized study of parallel design. Consecutive
ticagrelor naive patients who are referred for coronary angiography and have an
angiographically moderate to severe de novo stenosis (>50% and <90% diameter by visual
assessment) in at least one major epicardial coronary artery amenable to PCI are candidates
for this study. Patients after informed consent will be randomized (hour 0) to receive
immediately post FFR (with adenosine iintravenous infusion at 140 μg/Kg/min for a 3 minute
period) either ticagrelor 180mg loading dose or prasugrel 60mg/clopidogrel 600mg loading dose
(as clinically indicated). FFR examination will be repeated 2 hours post loading dose.