Abstract 17826: Plasma Biomarkers of Endothelial Dysfunction and Myocardial Fibrosis in Relation to Measures of Coronary Microvascular Disease in Ischemia With No Obstructive Coronary Arteries

Abstract

Background: Increased hyperemic microcirculatory resistance and/or low coronary flow reserve (CFR) diagnostic criteria for coronary microvascular disease in ischemia with no obstructive coronary arteries (INOCA). For optimal therapy pathophysiological mechanisms need to be determined. Aim: To investigate plasma levels of markers of i) endothelial dysfunction (syndecan-1, E-selectin, thrombomodulin and hyaluronan) and ii) myocardial fibrosis (procollagen type I carboxy-terminal propeptide [PICP], suppression of tumorigenicity 2 [ST2], and tissue inhibitor of metalloproteinases-1[TIMP-1]) in relation to the index of microcirculatory resistance (IMR) and CFR in INOCA. Methods: Measurements of corrected IMR and CFR were determined in the LAD using thermodilution technique during coronary angiography (CA) in chronic coronary syndrome (CCS) patients. Plasma biomarkers were quantified using an ELISA and the association between each biomarker and i) IMR and ii) CFR was analyzed using linear regression. Results: We selected 162 random patients with INOCA from a cohort of 503 all-comer CCS patients with no congestive heart failure that underwent CA with measurements of CFR and IMR in the LAD. The mean age was 65 ±10 years and 101 (62.3%) were male. Median IMR and CFR were 19.1 (interquartile range [IQR] 11.9-30.7) and 3.5 (IQR 2.3-5.1) respectively. IMR was associated with syndecan-1 (Figure 1A) but not with PICP (Figure 1C) or the other biomarkers. CFR was inversely associated with syndecan-1 (Figure 1B), PICP (Figure 1D), and E-selectin (p=0.049). Conclusion: IMR is associated with increasing plasma levels of syndecan-1 but not with myocardial fibrosis, indicating endothelial dysfunction, with glycocalyx shedding, to be involved in high hyperemic microcirculatory resistance in INOCA. Low CFR is also associated with PICP indicating involvement of myocardial fibrosis in coronary microvascular disease in INOCA.