IMR Press / RCM / Volume 25 / Issue 2 / DOI: 10.31083/j.rcm2502069
Open Access Original Research
Coronary Microvascular Function Assessment using the Coronary Angiography-Derived Index of Microcirculatory Resistance in Patients with ST-segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention
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1 Department of Cardiology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, 100730 Beijing, China
*Correspondence: (Huiping Zhang)
Rev. Cardiovasc. Med. 2024, 25(2), 69;
Submitted: 30 August 2023 | Revised: 14 October 2023 | Accepted: 23 October 2023 | Published: 20 February 2024
(This article belongs to the Special Issue Cardiac Catheterization: Clinical Updates and Novel Technologies)
Copyright: © 2024 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license.

Background: Studies reporting the status of coronary microvascular function in the infarct-related artery (IRA) after primary percutaneous coronary intervention (PCI) remain limited. This study utilized the coronary angiography-derived index of microcirculatory resistance (caIMR) to assess coronary microvascular function in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI. Methods: We used the FlashAngio system to measure the caIMR after primary PCI in 157 patients with STEMI. The primary endpoint was the occurrence of a major adverse cardiovascular event (MACE), defined as a composite endpoint encompassing cardiac mortality, target vessel revascularization, and rehospitalization due to congestive heart failure (CHF), myocardial infarction (MI), or angina. Results: Approximately 30% of patients diagnosed with STEMI and who experienced successful primary PCI during the study period had a caIMR in the IRA of >40. The caIMR in the IRA was significantly higher than in the reference vessel (32.9 ± 15.8 vs. 27.4 ± 11.1, p < 0.001). The caIMR in the reference vessel of the caIMR >40 group was greater than in the caIMR 40 group (30.9 ± 11.3 vs. 25.9 ± 10.7, p = 0.009). Moreover, the caIMR >40 group had higher incidence rates of MACEs at 3 months (25.5% vs. 8.3%, p = 0.009) and 1 year (29.8% vs. 13.9%, p = 0.04), than in the caIMR 40 group, which were mainly driven by a higher rate of rehospitalization due to CHF, MI, or angina. A caIMR in the IRA of >40 was an independent predictor of a MACE at 3 months (hazard ratio (HR): 3.459, 95% confidence interval (CI): 1.363–8.779, p = 0.009) and 1 year (HR: 2.384, 95% CI: 1.100–5.166, p = 0.03) in patients with STEMI after primary PCI. Conclusions: Patients with STEMI after primary PCI often have coronary microvascular dysfunction, which is indicated by an increased caIMR in the IRA. An elevated caIMR of >40 in the IRA was associated with an increased risk of adverse outcomes in STEMI patients undergoing primary PCI.

ST-segment elevation myocardial infarction
percutaneous coronary intervention
coronary microvascular function
coronary angiography-derived index of microcirculatory resistance
BJ-2018-201/National High Level Hospital Clinical Research Funding
Fig. 1.
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