The association between invasive microvascular function and CMR-derived microvascular injury indicators and left ventricular function and infarct size at 1-month after reperfused STEMI

Abstract Background The restoration of the coronary microcirculation in ST-segment elevation myocardial infarction (STEMI) patients remains hampered in up to 50% of the STEMI patients after successful primary percutaneous coronary intervention (PCI). The association between the coronary microvascular function and injury indicators and functional outcome remains debated. Purpose This study aims to investigate the relation between post-PCI invasive microvascular function and cardiovascular magnetic resonance (CMR)-derived microvascular injury indicators and left ventricular (LV) function and infarct size (IS) at 1-month after STEMI. Methods The study was performed in 110 STEMI patients who underwent angiography for primary PCI and at 1-month follow-up. Invasive assessment of coronary microcirculation physiology in the culprit artery was performed during both procedures and included coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR). Data were available for 101 patients. A ratio of >2 for CFR and a value of <25 U for IMR were considered normal. CMR was performed during the acute phase (2 to 7 days after PCI) and at 1-month and provided assessment of LV function, IS and non-invasive information of microvascular injury in 78 patients by microvascular obstruction (MVO) and intra-myocardial hemorrhage (IMH). Results Over 1-month, CFR, IMR, LV function, and IS all significantly improved (p≤0.001). In univariable linear regression analysis, the post-PCI normal index CFR and IMR (both p=0.04), MVO presence, MVO size, IMH presence, IMH size (all, p<0.001) were significantly associated with LV ejection fraction at 1-month. Additionally, the post-PCI index CFR (p=0.04), MVO presence, MVO size, IMH presence, IMH size (all, p<0.001) were all associated with 1-month IS. In a multivariable linear regression analysis model including invasive and non-invasive coronary microcirculation function and injury indicators, MVO presence was identified as the only independent marker related to both 1-month LV ejection fraction and IS (both p<0.001). Conclusion(s) In STEMI patients, CMR-derived coronary microcirculation injury indicators reveal a closer association with 1-month LV function and IS outcome than invasive microcirculatory measurements. MVO presence is independently associated with 1-month LV ejection fraction and IS. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): The REDUCE-MVI study was funded by Astra Zeneca to MvL and NvR.