Abstract 9775: The Effect of Microvascular Injury on Temporal Evolution of Invasive Microvascular Function Indices After Reperfused ST-Segment Elevation Myocardial Infarction

Abstract

Background: Despite successful primary percutaneous coronary intervention (PCI), the restoration of the microvascular flow fails in up to 50% of the reperfused ST-segment elevation myocardial infarction (STEMI) patients, worsening the prognosis. This study aims to identify how post-STEMI microvascular function indices evolve over 1-month and how these changes are affected by the presence of microvascular injury. Methods: The study was performed in 110 STEMI patients who underwent angiography for primary PCI and at 1-month follow-up. Invasive assessment of the coronary microcirculation in the culprit artery was performed during both procedures and included coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and baseline microcirculatory resistance (BMR). Cardiovascular magnetic resonance imaging was performed 2 to 7 days after PCI to evaluate microvascular injury by microvascular obstruction (MVO) and intra-myocardial hemorrhage (IMH). Results: Over 1-month, mean CFR, IMR, and BMR all changed significantly (fig. 1). CFR increased in all patients both with and without MVO and IMH (all, p<0.001). IMR significantly decreased in patients with MVO (p<0.001) and IMH (p<0.01), but less apparently in patients without MVO (p=0.04) and IMH (p=0.05). There was no significant difference for the absolute CFR change over 1-month between patients with/without MVO (p=0.34) and with/without IMH (p=0.41). The absolute IMR change over 1-month differed significantly between patients with/without MVO (p<0.01) and with/without IMH (p=0.001). Conclusion(s): In STEMI patients, coronary microvascular function indices significantly improved one month after PCI. The occurrence of microvascular damage presented a close interaction with the recovery of IMR but not with the course of CFR.