Better Coronary Microvascular Function With Ticagrelor vs Clopidogrel in Non-ST Elevation ACS

Ticagrelor treatment resulted in improved preservation of coronary microvascular function and peripheral endothelial function when compared with clopidogrel in patients with non-ST elevation acute coronary syndrome (NSTEACS).  These findings were presented during the American College of Cardiology Annual Meeting, held virtually from May 15 to 17, 2021.

Although studies have shown ticagrelor reduces microvascular injury in comparison with clopidogrel in patients with ST-elevation myocardial infarction (STEMI) who are undergoing percutaneous coronary intervention (PCI) and improves peripheral endothelial function in stable patients, data are lacking for ticagrelor vs clopidogrel in patients with NSTEACS. To fill this gap, investigators conducted a prospective, randomized study.

The researchers randomly assigned 128 NSTEACS patients 1:1 to clopidogrel (600-mg loading dose then 75 mg daily) or ticagrelor (180-mg loading dose then 90 mg twice daily) from March 2018 to July 2020.

Ten patients were excluded, and 4 of the remaining patients crossed over from clopidogrel to ticagrelor. Coronary microvascular function with index of microcirculatory resistance (IMR) was assessed, along with peripheral endothelial function with flow-mediated vasodilation of the brachial artery, which investigators expressed as a percentage change in poststimulus diameter or functional mitral regurgitation (%FMD).

Of the 118 randomly assigned patients included for analysis (58 clopidogrel, 60 ticagrelor), the median patient age was 59 (interquartile range [IQR], 51-68.8) years, and 100 (84.7%) of them were men.

At baseline, the median Global Registry of Acute Coronary Events (GRACE) score was 93.5 (79.3-109), and the median peak troponin was 421 (176.5-939.8) ng/L. The median IMR in the infarct-related artery (IRA) was higher at baseline in the clopidogrel group compared with the ticagrelor group (intention to treat, 27.7 [19.3-39.8] vs 22.0 [13.0-34.9]; P =.02; per protocol, 29.5 [19.3-39.8] vs 22.0 [13.0-34.9]; P =.02). No differences were noted in baseline IMR of the non-IRA (19.0 [14.0-26.0] vs 18.0 [12.6-25.0]; P =.39).

In all, 88 patients had PCI (43 clopidogrel, 45 ticagrelor), and median post-PCI IMR was higher in the clopidogrel group compared with the ticagrelor group (intention to treat, 27.0 [18.5-47.5] vs 22.0 [15.0-29.0]; P =.02; per-protocol, 28.0 [18.3-49.3] vs 22.0 [15.0-29.0]; P =.02).

A total of 69 patients had %FMD evaluated (clopidogrel n=33, ticagrelor n=36). At baseline no differences between the 2 groups were seen in median %FMD (10.9% [8.1-15.6] vs 10.5% [5.9-10.6]; P =.34).

Predischarge median %FMD was lower in the clopidogrel group compared with the ticagrelor group (8.1% [4.6-11.4] vs 13.5% [10.7-17.1]; P =.0002).

Study investigators concluded, “In NSTEACS, ticagrelor resulted in better preservation of coronary microvascular function and improved peripheral endothelial function compared [with] clopidogrel.”

Reference

Xu J, Lo S, Mussap C, et al. Impact of clopidogrel versus ticagrelor on coronary microvascular function and peripheral endothelial function after non-ST elevation acute coronary syndrome: a prospective randomized study. Presented at: American College of Cardiology (ACC) 2021 Annual Meeting; May 15-17, 2021. Abstract 1016-08.