Reduced heart-rate variability and increased risk of hypertension-a prospective study of the ELSA-Brasil.

Although autonomic disturbances are known to precede hypertension onset, the risks underlying different ranges of blood pressure and impaired cardiac autonomic modulation are still unknown. This study aimed to identify the risk of hypertension incidence related to low heart-rate variability profile in normotensive blood pressure subcategories: normal (<120/80 mmHg) and prehypertension (120/80-139/89 mmHg) in a 4-year follow-up. 7665 participants free of hypertension at baseline were examined. They were allocated into one of two groups (<P25 and ≥P25) based on age-specific value distributions of heart-rate variability ranges presented in the literature. The relationship between heart-rate variability parameters (SDNN, RMSSD, VLF, LF, and HF) and hypertension incidence was analyzed using Poisson regression. The reference for the independent variable in these regressions was the dataset with all HRV values ≥P25. After full adjustments for age, sex, ethnicity, educational level, body mass index, smoking status, glucose, insulin, dyslipidemia, alcohol consumption, and physical activity, low values for all heart-rate variability indices were significantly associated with an increased relative risk of developing hypertension in the overall sample. Individuals with normal BP levels presented an increased risk for low SDNN, VLF, and LF values, whereas the risk in prehypertensive participants was only verified for low VLF. In conclusion, cardio autonomic disturbances precede the incidence of clinical hypertension and are potentially involved in its pathophysiological basis and progression. Even individuals with normal blood pressure may be at an increased risk for future hypertension in the presence of reduced cardio autonomic control.