Myocardial interaction of apixaban after experimental acute volume overload.

OBJECTIVE: Acute volume overload (AVO) induces early ischemia-like changes in intramyocardial arteries. We investigated whether the Factor Xa (FXa) inhibitor apixaban interacts with the myocardium early after AVO. METHODS: Fifty-five syngeneic Fisher rats underwent surgical abdominal aortocaval fistula to induce AVO. Among them, 17 rats were treated with apixaban (10 mg/kg/day). The myocardial outcome was studied using histological analysis and by measuring atrial natriuretic peptide (ANP) and matrix metalloprotease 9 (MMP9) gene expression. RESULTS: After 3 days, the total number of intramyocardial arteries was significantly increased in the AVO+apixaban (AVO+A) group compared with that in the AVO group (12.0 ± 1.2 and 10.2 ± 1.5, point score units, respectively). In the AVO+A group, there were significantly more edematous nuclei in myocardial arteries in the right and left ventricle compared with that in the AVO group. ANP and MMP9 expression levels continued to increase significantly in the AVO+A group compared with those in the AVO group. CONCLUSION: Apixaban interacts with intramyocardial arteries in the left and right ventricles after AVO and ANP and MMP9 expression levels increased. Thus, the myocardial effect of Factor Xa inhibition needs to be monitored after AVO.

Early reversibility of histological changes after experimental acute cardiac volume-overload.

Unloading the heart may aid recovery after acute cardiac volume-overload (AVO). We experimentally investigated whether unloading the heart after AVO by heterotopic transplantation histologically impacts myocardial outcome. Thirty-two syngeneic Fisher 344 rats underwent surgery for abdominal arterial-venous fistula to induce AVO. Seven hearts were heterotopically transplanted one day after AVO to simulate a non-working state of the left ventricle (AVO+Tx). In addition, six rats without AVO or surgery (Normal) and five rats with sham surgery (Sham) served as controls. Myocardial outcome was studied using histology and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis for hypoxia inducible factor 1alpha (HIF1α), inducible nitric oxide synthase (iNOS), E-selectin, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), vascular endothelial growth factor alpha (VEGFα), matrix metalloprotease 9 (MMP9), chitinase-3-like protein (YKL-40) and transforming growth factor beta (TGFß). Relative ischemia of the right ventricle and septal intramyocardial arteries was decreased in AVO+Tx as compared with AVO (0.04±0.01 vs. 0.09±0.02, PSU, P=0.040 and 0.04±0.01 vs. 0.16±0.02, PSU, P=0.008, respectively). Quantitative RT-PCR showed an increase in the expression of iNOS, YKL-40 and VEGFα, and decrease in ANP in AVO+Tx as compared with AVO (5.78±1.23 vs. 2.46±0.81, P=0.039, 22.39±5.22 vs. 10.79±1.70, P=0.039 and 1.15±0.22 vs. 0.60±0.08, P=0.030, and 1.32±0.16 vs. 2.85±0.70, P=0.039, respectively). Unloading the heart by heterotopic transplantation induces early ischemic recovery of intramyocardial arteries after AVO. A non-working state reverses acute ischemic myocardial injury after AVO.