B-PO03-030 EFFICACY OF ESTROGEN SUPPLEMENT ON VENTRICULAR SUBSTRATE IN A RABBIT MODEL OF MENOPAUSE

Abstract

Sympathetic hyperactivity in menopausal subjects may lead to autonomic dysfunction and arrhythmic vulnerability. Estrogen supplement has beneficial effects on the cardiovascular diseases, however, the efficacy of hormone therapy is questionable. We aimed to evaluate the efficacy of estrogen supplements in the myocardial substrates of menopausal rabbits with ovariectomy (OVX). Eight-teen New Zealand female rabbits were randomized into control (n=6), OVX (n=6), and OVX-Estrogen (OVX-E) group (n=6). The menopause model was done by bilateral OVX. All rabbits received blood samples, EP studies, and VT inducibility tests (Max output with shortest 1:1 cycle length pacing) with a high-density contact multielectrode mapping after induction of sustained VT. Myocardium was harvest for Trichrome and tyrosine stain. The estrogen and progesterone levels of the 3 groups are shown in Figure A. The atrial and ventricular ERPs in the OVX group were significantly longer than the control and OVX+E group (Fig. B, C). The VT inducibility of the OVX-E group was significantly higher than the control group (18.41±1.88% vs. 7.01±1.65%, p=0.035). The ventricular fibrotic tissue of the OVX group was significantly higher than OVX-E and control group (Fig. D). The LV and RV sympathetic innervation in the OVX group were significantly increased than the control and OVX+E group (Fig. E). Menopause leads to cardiac remodeling and increases ventricular arrhythmogenicity. Estrogen supplements can improve vulnerability to VT, decrease fibrosis formation, and decrease sympathetic innervation.