Evaluation of Microvascular Injury in Revascularized Patients with ST Elevation Myocardial Infarction Treated with Ticagrelor versus Prasugrel: The REDUCE-MVI Trial.

BACKGROUND Despite successful restoration of epicardial vessel patency with primary percutaneous coronary intervention (pPCI), coronary microvascular injury (MVI) occurs in a large proportion of STEMI patients, adversely affecting clinical and functional outcome. Ticagrelor has been reported to increase plasma adenosine levels, which might have a protective effect on the microcirculation. We investigated if ticagrelor maintenance therapy after revascularized STEMI is associated with less MVI compared to prasugrel maintenance therapy. METHODS A total of 110 STEMI patients received a loading dose of ticagrelor and were randomized to maintenance therapy of ticagrelor (n=56) or prasugrel (n=54) after pPCI. The primary outcome was MVI at 1 month, as determined with the index of microcirculatory resistance (IMR) in the infarct-related artery. Cardiovascular magnetic resonance imaging was performed during the acute phase and at one month. RESULTS The primary outcome of IMR was not superior in ticagrelor or prasugrel treated patients (ticagrelor 21 [15-39] U, prasugrel 18 [11-29] U, p=0.08). Recovery of microcirculatory resistance over time was not better in patients with ticagrelor versus prasugrel (ticagrelor -13.9 U vs. prasugrel -13.5 U, p=0.54). Intramyocardial hemorrhage was observed less frequently in patients with ticagrelor (23% vs. 43%, p=0.04). At one month no difference in infarct size was observed (ticagrelor 7.6 [IQR 3.7-14.4] g, prasugrel 9.9 [IQR 5.7-16.6] g, p=0.17). The occurrence of microvascular obstruction was not different in patients on ticagrelor (28%) or prasugrel (41%, p=0.35). Plasma adenosine concentrations were not different during the index procedure and during maintenance therapy with ticagrelor or prasugrel. CONCLUSIONS In patients with STEMI, ticagrelor maintenance therapy was not superior to prasugrel in preventing MVI in the infarct-related territory as assessed by IMR and this resulted in a comparable infarct size at one month. CLINICAL TRIAL REGISTRATION URL: https://clinicaltrials.gov Unique identifier: NCT02422888.