Abstract
BACKGROUND: Hypertension (HTN) remains a serious risk factor for cardiovascular mortality across the world. Hypertensive state has been shown to be associated with autonomic nervous function. This study aimed to explore the association between autonomic nervous impairment assessed by heart rate variability (HRV) and HTN. METHODS: A total of 52 hypertensive and 55 non-hypertensive patients were consecutively studied using 24-hour Holter. The hypertensive patients were grouped into controlled blood pressure (BP) and uncontrolled BP. This study compared HRV in non-hypertensive and hypertensive patients; and hypertensive patients with controlled and uncontrolled BP. HRV parameters include time and frequency domain. RESULTS: Mean age for hypertensive and non-hypertensive patients were 53.58 ± 14.31 and 44.89 ± 16.63 years old, respectively. Median (IQR) SDNN for hypertensive and non-hypertensive group were 109.00 (90.00-145.00) and 129.00 (107.00-169.00), respectively. SDNN, ASDNN, rMSSD, pNN50, BB50, VLF, and HF values were significantly lower in the hypertensive group compared to non-hypertensive group (all P < .05). A multiple regression analysis showed that HRV parameters: SDANN, ASDNN, rMSSD, and LF values were independent risk factors of HTN. SDNN, SDANN, ASDNN, VLF, LF, and HF values were significantly lower in the uncontrolled BP compared to controlled BP group (all P < .05). A multiple regression analysis showed that HRV parameters: SDNN, SDANN, rMSSD, and HF values were independent risk factors of uncontrolled BP in hypertensive patients. CONCLUSIONS: Our study showed that cardiac autonomic nervous impairment, as demonstrated by reduced HRV, is significantly associated with HTN. Decreased HRV was more evident in uncontrolled BP than in controlled BP group.