Cardiovascular disease progression in female Zucker Diabetic Fatty rats occurs via unique mechanisms compared to males

Population studies have shown that compared to diabetic men, diabetic women are at a higher risk of cardiovascular disease. However, the mechanisms underlying this gender disparity are unclear. Our studies in young murine models of type 2 diabetes mellitus (T2DM) and cardiovascular disease show that diabetic male rats develop increased cardiac fibrosis and suppression of intracardiac anti-fibrotic cytokines, while premenopausal diabetic female rats do not. This protection from cardiac fibrosis in female rats can be an estrogen-related effect. However, diabetic female rats develop early subclinical myocardial deformation, cardiac hypertrophy via elevated expression of pro-hypertrophic miR-208a, myocardial damage, and suppression of cardio-reparative Angiotensin II receptor 2 (Agtr2). Diabetic rats of both sexes exhibit a reduction in cardiac capillary density. However, diabetic female rats have reduced expression of neuropilin 1 that attenuates cardiomyopathy compared to diabetic male rats. A combination of cardiac hypertrophy and reduced capillary density likely contributed to increased myocardial structural damage in diabetic female rats. We propose expansion of existing cardiac assessments in diabetic female patients to detect myocardial deformation, cardiac hypertrophy and capillary density via non-invasive imaging, as well as suggest miR-208a, AT2R and neuropilin 1 as potential therapeutic targets and mechanistic biomarkers for cardiac disease in females.

Doppler Tissue Imaging Is More Sensitive Than Other Echocardiographic Markers in Identifying Abnormal Relaxation in Subclinical Hypertensive Disease and Normal Ejection Fraction

This report describes the use of echocardiographic measurements for the assessment of left ventricular diastolic function in two young patients with newly diagnosed hypertension. Measurements for the assessment of left ventricular relaxation and filling pressures included mitral inflow, Doppler tissue imaging (DTI), color M-mode propagation velocity slope, and the isovolumic relaxation time. The mitral inflow, propagation velocity, and isovolumic relaxation time measurements were all within normal limits; however, DTI measurements of the E′ velocity at the septal and lateral annulus were significantly reduced in both patients. Further visual inspection demonstrated discrete proximal septal wall thickening that is thought to be modulated by pressure loading (i.e., increased afterload due to hypertension) and ejection. These findings may represent a “transitional state” of early ventricular remodeling and organ failure in the development of hypertensive disease. In summary, DTI appears to be more sensitive compared to other markers in identifying abnormal relaxation in subclinical hypertensive disease and normal ejection fraction.