(P116) SEX DIFFERENCES IN PULMONARY AND SYSTEMIC VASCULAR FUNCTION AT REST AND DURING EXERCISE IN HEALTHY OLDER ADULTS

Background: Age-related ventricular-vascular stiffening may predispose to the development of heart failure with preserved ejection fraction and exertional intolerance. Sex differences observed in diseased states may be rooted in sexual dimorphism observed in health and it has been postulated that such differences may influence susceptibility to disease. Therefore, our aim was to explore potential sex-differences in pulmonary and systemic vascular function in healthy individuals both at rest and during submaximal exercise.

METHODS AND RESULTS: Healthy individuals underwent right heart catheterization at rest and during constant submaximal semi-upright cycling. Hemodynamics were collected continuously and pulmonary artery wedge pressure (PAWP) was recorded every 2 minutes. Data was collected in a control state while seated semi-upright without cycling and with moderate exercise, which was defined as exercise with a target heart rate of 120bpm. Pulmonary and systemic vascular variables including: compliance, resistance, and elastance were calculated, indexed to body surface area (BSA), adjusted for age and compared between male and female sex. Thirty-six individuals (18M/18F; 54±7 vs. 58±6 years, p=0.04) were included in this study. In the pulmonary circuit, when adjusted for age and indexed to BSA, there was significantly higher total pulmonary resistance (TPulmR) (516±73 vs. 424±118 dyn•s•cm-5•m-2, p=0.03) and pulmonary effective arterial elastance (PEa) (0.41±0.1 vs. 0.32±0.1 mmHg•mL-1•m2, p=0.03) in females when compared to males. Both pulmonary compliance (Cpa) and systemic compliance (Csa) were lower in females vs. males however lost significance when adjusting for age. However, systemic arterial elastance (SEa) was higher in women (1.65±0.29 vs. 1.31±0.24 mmHg•mL-1, p=0.05). Secondary analyses demonstrated significant correlations between age and PVR (r=0.33, p=0.05), TPulmR (r=0.35, p=0.04), Cpa (r=-0.48, p< 0.01), and PEa (r=0.37, p=0.03). During exercise, there were significantly greater increases in TPulmR (p=0.02) and PEa (p=0.01) from control to moderate exercise in females vs. males.

Conclusion: TPulmR and PEa are significantly higher at rest in females compared to males, and continue to remain higher with exercise. Cpa and Csa were lower in females when compared to males, however this observation was confounded by higher age amongst the females studied. Our results are consistent with the notion that increased pulmonary and systemic vascular stiffening associated with increased RV afterload are observed in both older age and in females, independent of heart failure.