Sex Differences in the Relationship Between Arterial Stiffness and Physical Fitness in Maintenance Hemodialysis Patients

Abstract

Maintenance hemodialysis (HD) patients have high levels of arterial stiffness which contribute to elevated mortality. Previously, we demonstrated that aortic stiffness contributes to reduced physical fitness; however sex differences, particularly in body size, may influence the relationship between arterial stiffness and alterations in left-ventricular work and perfusion. PURPOSE: Therefore, we determined if sex differences existed in the relationship between arterial stiffness, wave reflection, and physical fitness in HD patients. METHODS: Brachial blood pressure (BP), carotid-femoral pulse wave velocity (PWV), and pulse wave analysis were collected on a non-dialysis day using standard laboratory techniques. Following cardiovascular (CV) measures, patients underwent an incremental shuttle walk test (ISWT) to assess aerobic fitness. RESULTS: 121 HD patients (72 males, Age 55 ± 12y) underwent testing. There were no sex differences in age, diabetes, smoking status, BMI, or any measure of brachial BP (p > 0.05 for all). Males were taller (173.1 ± 8.3 vs 160.8 ± 6.6cm, p < 0.001) and tended to have higher PWV (10.3 ± 3.0 vs 9.3 ± 3.1m/s, p = 0.071). However, females exhibited higher augmented pressure (AP) (17.0 ± 9.2 vs 11.5 ± 8.7mmHg, p = 0.002) and augmentation index (AIx) (23.5 ± 12.4 vs 31.8 ± 11.9%, p = 0.001); even when normalized to heart rate (22.4 ± 11.4 vs 29.7 ± 12.0%, p = 0.002). Males performed better (longer time) on the ISWT than females (260.5 ± 120.8 vs 210.2 ± 95.0s, p = 0.018). Among the whole cohort, PWV, AIx, and AP were all negatively associated with ISWT and Subendocardial Viability Ratio (SEVR) was positively correlated (p<0.05 for all). When these variables were entered into a stepwise regression to predict shuttle walk performance, AP and SEVR remained in the model for males (r = 0.397, p = 0.005), while in females only PWV was a significant predictor (r = 0.359, p = 0.019). CONCLUSIONS: Measures of arterial stiffness, wave reflection, and aerobic fitness differed in male and female HD patients. Furthermore, CV predictors of aerobic fitness differed between sexes. These data suggest that different factors may contribute to poor aerobic fitness in male and female HD patients. Supported by funding from the NIH (1R01DK084016)