Background Off-target properties of
ticagrelor might reduce microvascular injury and improve clinical outcome in patients with
ST-segment-elevation myocardial infarction. The REDUCE-MVI (Evaluation of Microvascular Injury in Revascularized Patients with
ST-Segment-Elevation Myocardial Infarction Treated With
Ticagrelor Versus
Prasugrel) trial reported no benefit of
ticagrelor regarding microvascular function at 1 month. We now present the follow-up data up to 1.5 years. Methods and Results We randomized 110 patients with
ST-segment-elevation myocardial infarction to either
ticagrelor 90 mg twice daily or
prasugrel 10 mg once a day. Platelet inhibition and peripheral endothelial function measurements including calculation of the
reactive hyperemia index and clinical follow-up were obtained up to 1.5 years. Major adverse clinical events and bleedings were scored. An intention to treat and a per-protocol analysis were performed. There were no between-group differences in platelet inhibition and endothelial function. At 1 year the
reactive hyperemia index in the
ticagrelor group was 0.66±0.26 versus 0.61±0.28 in the
prasugrel group (P=0.31). Platelet inhibition was lower at 1 month versus 1 year in the total study population (61% [42%-81%] versus 83% [61%-95%]; P<0.001), and per-protocol platelet inhibition was higher in patients randomized to
ticagrelor versus
prasugrel at 1 year (91% [83%-97%] versus 82% [65%-92%]; P=0.002). There was an improvement in intention to treat endothelial function in patients randomized to
ticagrelor (P=0.03) but not in patients randomized to
prasugrel (P=0.88). Major adverse clinical events (10% versus 14%; P=0.54) and bleedings (47% versus 63%; P=0.10) were similar in the intention-to-treat analysis in both groups. Conclusions Platelet inhibition at 1 year was higher in the
ticagrelor group, without an accompanying increase in bleedings. Endothelial function improved over time in
ticagrelor patients, while it did not change in the
prasugrel group. Clinical Trial Registration URL: https://www.clinicaltrials.gov/. Unique Identifier: NCT02422888.