Heart rate variability, HIV and cardiovascular disease risk in rural South Africa

Background: The increased use of anti-retroviral therapy (ART) transformed
human immunodeficiency virus (HIV) infection into a chronic
disease. Possible HIV-associated complications have emerged including
cardiovascular diseases (CVD). Surrogate markers can estimate CVD
risk, however data from high HIV-prevalence areas such as rural South
Africa are limited. This study aims to determine
1) the distribution of heart rate variability (HRV), a surrogate marker of
CVD risk,
2) the association between HIV and HRV and
3) the association between ART and HRV in the rural South African population.

Methods: Participants of the Ndlovu Cohort Study visiting the research
centre in Elandsdoorn, South Africa between August and December
2017 were included in this cross-sectional study. HRV was measured
using a standardized 5-min resting ECG. HRV was determined using
total-frequency (0.04 to 0.5 Hz), low-frequency (0.04 to 0.15 Hz), highfrequency
power (0.15 to 0.5 Hz), standard deviation of the normal RR
intervals (SDNN), the root of the mean squares of successive RR differences
(RMSSD) and the percentage of RR intervals greater than fifty
milliseconds different from its predecessor (pNN50). All parameters
had a skewed distribution and were log-transformed for multivariable
analysis. Information on gender, body mass index (BMI), age, medication
use, blood pressure, physical activity, education and income level were
obtained using standardized questionnaires. The Kruskal Wallis test was
used to test a difference in medians between HIV-infected and HIVuninfected
participants. Multivariable linear regression analyses were
performed to identify predictors of HRV.

Results: In total 325 participants were included, of whom 202 (62.2%)
were HIV-infected. All HRV parameters (median values) were lower for
the HIV-infected compared to the HIV-uninfected participants. The multivariate
models showed a significant inverse association between HIV
and SDNN, RMSSD, pNN50 and LF power, and between age and all HRV
parameters. There was no indication of a difference in HRV between participants
on ART versus not on ART.

Conclusions: These findings show that HIV-infected participants have
a lower HRV, indicating an increased risk of CVD and this suggests that
embedding of CVD prevention in HIV-care is necessary