Impact of Ticagrelor Versus Clopidogrel on Coronary Microvascular Function After Non–ST-Segment–Elevation Acute Coronary Syndrome

Background: Coronary microvascular dysfunction after acute coronary syndrome is an important predictor of long-term prognosis. Data is lacking on the effects of oral P2Y 12 -inhibitors on coronary microvascular function in non–ST-segment–elevation acute coronary syndrome. The aim of this study was to compare the acute effects of ticagrelor versus clopidogrel pretreatment on coronary microvascular function in non–ST-segment–elevation acute coronary syndrome patients. Methods: Hospitalized non–ST-segment–elevation acute coronary syndrome patients were randomized (1:1) to ticagrelor or clopidogrel. The index of microcirculatory resistance, coronary flow reserve, and resistive reserve ratio were obtained using an intracoronary pressure-temperature sensor-tipped wire. Results: In total, 128 patients were randomized between March 2018 and July 2020. Mean age 59.2±11.8 years, 84% were male, mean Global Registry of Acute Coronary Events score was 93.7±24.5. Intracoronary physiological measurements were obtained in 118 patients (60 ticagrelor, 58 clopidogrel). In the infarct-related artery, the ticagrelor group had lower baseline index of microcirculatory resistance (22.0 [13.0–34.9] versus 27.7 [19.3–29.8]; P =0.02) and higher baseline resistive reserve ratio (3.0 [2.3–4.4] versus 2.4 [1.7–3.4]; P =0.01) compared with the clopidogrel group. A total of 88 patients underwent percutaneous coronary intervention (PCI; 45 ticagrelor, 43 clopidogrel). The ticagrelor group had lower post-PCI index of microcirculatory resistance (22.0 [15.0–29.0] versus 27.0 [18.5–47.5]; P =0.02) and higher post-PCI resistive reserve ratio (3.0 [1.8–3.8] versus 1.8 [1.5–3.4]; P =0.006) compared with the clopidogrel group. The coronary flow reserve was not significantly different between the 2 groups at baseline or post-PCI. No between-group differences were seen in any of the indices in the non-infarct-related artery. Conclusions: In non–ST-segment–elevation acute coronary syndrome patients, ticagrelor significantly improved coronary microvascular function before and after PCI compared with clopidogrel. Registration: URL: https://www.anzctr.org.au ; Unique identifier: ACTRN12618001610224.