Association between cardiac parasympathetic tone and beat-to-beat blood pressure average real variability

Introduction: Epidemiological evidence supports the utility of 24-hour ambulatory and visit-to-visit blood pressure average real variability (ARV) as a prognostic indicator of adverse cardiovascular outcomes. Quantification of blood pressure ARV as a biomarker for cardiovascular risk has recently been adopted in studies assessing beat-to-beat blood pressure. However, beat-to-beat blood pressure ARV may be influenced by pronounced parasympathetic modulation of heart period and slowing of heart rate between subsequent cardiac cycles, which could augment beat-to-beat blood pressure ARV challenging its utility as a cardiovascular risk marker. The purpose of the present study was to investigate the association between estimates of cardiac parasympathetic tone using heart rate variability (HRV) and beat-by-beat blood pressure ARV alongside other commonly used blood pressure variability metrics in a large population of young, otherwise healthy adults. Methods: Ten-minute continuous recordings of resting heart rate (HR, electrocardiogram) and beat-to-beat blood pressure (finger plethysmography) were obtained in 139 healthy young adults (88 males, 51 females; age: 22±4; BMI: 24±3). High frequency HRV (HF-HRV) and root-mean squared of successive differences (RMSSD) were used to characterize HRV alongside cardiovagal-baroreflex sensitivity in the up (cvBRSup) and down (cvBRSdown) sequences. Blood pressure variability was quantified using the ARV and standard deviation (SD) for beat-to-beat systolic (SBP) and diastolic (DBP) blood pressure across the 10-minute resting period in each participant. Bivariate correlations were employed to determine associations between measures of HRV, cvBRS, and blood pressure variability. Results: Heart rate variability was significantly associated with SBP ARV (RMSSD: r=0.416, p0.263). Cardiovagal baroreflex sensitivity was associated with DBP ARV (cvBRSup: r=0.621, p< 0.001; cvBRSdown: r=0.601, p< 0.001), but not SBP ARV (cvBRSup: r=0.077, p=0.404; cvBRSdown: r=0.076, p=0.408). Modest negative associations were observed between cvBRSdown and SBP SD (r= -0.252, p=0.005), but not DBP SD (r = -0.143, p=0.118). cvBRSup was not associated with SBP SD (r=-0.159, p=0.081) or DBP SD (r=-0.063, p=0.492). Discussion: The present findings demonstrate a prominent linear association between HRV, cardiovagal baroreflex sensitivity, and beat-to-beat blood pressure ARV. As higher HRV is commonly associated with positive health outcomes, the linear association between HRV and blood pressure ARV challenges the assumption that elevated beat-to-beat blood pressure ARV serves as a robust and reliable cardiovascular risk marker, at least within young, otherwise healthy adults. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.