Cardiac Autonomic Function in Young, Healthy Adults: Influence of Race and Sex.

Abstract

Non-Hispanic Black (BL) adults living in the U.S. are more likely to develop cardiovascular disease (CVD) compared to their Non-Hispanic White (WH) counterparts. While measures of cardiac autonomic function [i.e., spontaneous cardiac baroreflex sensitivity (BRS), heart rate variability (HRV)] have a predictive value for CVD, studies investigating racial differences in cardiac autonomic function are limited and have reported conflicting results. Furthermore, sex differences are often not considered despite BL women having a high prevalence of CVD. We hypothesized that young BL men and women would exhibit lower cardiac BRS and HRV compared to their WH counterparts. Heart rate and beat-to-beat blood pressure were continuously recorded during 5 minutes of supine rest in 145 young (18-33 years), healthy, BL (37 men, 38 women) and WH (39 men, 31 women) adults to assess cardiac BRS and HRV. Overall cardiac BRS (sequence method) was higher in BL adults compared to WH adults (p < 0.001), which was mainly driven by differences between BL and WH men (BL men: 34±16 vs. WH men: 21±9 ms/mmHg, p < 0.001) compared to women (BL women: 27±12 vs. WH women: 24±11 ms/mmHg; p > 0.05). Likewise greater HRV in BL adults, indexed by root mean square of successive differences (RMSSD), was primarily driven by BL men (BL men: 109±59 vs. WH men: 64±33 ms; p < 0.001) rather than BL women (p > 0.05). Thus, contrary to our hypothesis, these results support that reduced cardiac autonomic function does not manifest early in life among young BL adults.