Background: Hypertension, one of the modifiable risk factors for cardiovascular disease (CVD), is known to be associated with increased oxidative stress and reduced cardiovagal modulation. Similar to hypertension, prehypertension is associated with increased risk of adverse cardiovascular (CV) events. We planned this study to find the association between prehypertension, cardiovagal modulation, oxidative stress, and associated CV risk factors.
Methods: We recruited 178 subjects through hypertension screening camps conducted in Puducherry, India. Subjects were grouped into prehypertensive (n = 97) and normotensive (n = 81) groups. They were further subdivided, based on age, as young (20-39 years) and middle-aged (40-60 years) adults. We measured basal physiological parameters, heart rate variability, oxidative stress (thiobarbituric acid reactive substance and total antioxidant capacity (TAC)), and CV risk factors.
Results: We found significant increase in oxidative stress in prehypertensive subjects of both age groups but the cardiovagal modulation decreased significantly in young prehypertensive subjects when compared with normotensive subjects. Correlation of TAC with root mean square of the sum of successive R wave to R wave (RR) interval differences (RMSSD), a cardiovagal modulation parameter (r = 0. 437; P < 0.001), and mean arterial pressure (MAP) (r = -0.318; P < 0.001) was significant even after adjusting for CV risk factors. The correlation between MAP and RMSSD (r = 0.199; P = 0.009) was reduced after adjusting for CV risk factors.
Conclusions: Prehypertension in young adults is associated with increased oxidative stress and altered cardiovagal modulation. The risk factors for CVDs in prehypertensive young adults were found to be equivalent to that of middle-aged adults who are in the twilight zone for developing CV dysfunctions.
Keywords: blood pressure; cardiovascular risk factors; heart rate variability; hypertension; oxidative stress; prehypertension.