Effect of Ticagrelor on Fractional Flow Reserve

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.