THE EFFECT OF SYMPATHETIC NERVOUS SYSTEM HYPERACTIVITY ON A 6-MONTH BLOOD PRESSURE REGULATION IN HYPERTENSIVE PATIENTS WITH OR WITHOUT NONALCOHOLIC FATTY LIVER DISEASE

Objective: Non-alcoholic fatty liver disease (NAFLD) is the most important cause of chronic liver disease and a marker of an independent cardiovascular risk. The purpose of this study was to investigate the interrelations between sympathetic nervous system (SNS) tone, as assessed by microneurography, and blood pressure levels (BP) on a 6 months follow up in hypertensive subjects with and without NAFLD. Design and method: 141 newly diagnosed, untreated hypertensive patients (mean age 55±10 years, 66 males) without alcohol consumption, cardiovascular disease or diabetes mellitus were included. Patients were categorized into two groups based on the Fatty Liver Index (FLI > 60 indicative of NAFLD, < 60 control group) and underwent 24-hour ambulatory blood pressure monitoring (ABPM). SNS overactivity levels were assessed at the baseline visit by direct recording of muscle sympathetic nerve activity (MSNA), based on an established technique (microneurography). Participants were treated with optimal antihypertensive therapy according to the European guidelines and after 6 months underwent a new 24-hour ABPM. Results: Hypertensive subjects with FLI>60 (n=74) compared to controls (n=67) were younger (53±10 vs. 57±9 years, respectively, p=0.01) and had higher body mass index (33± vs. 26±3 kg/m2, p<0.001). They also had statistically significant higher levels of triglycerides (133±50 vs 100±40 mg/dl, p<0.04) as well as Homeostatic Model Assessment for Insulin Resistance (3,1±2 vs 1,7±1, p<0.001). Hypertensive patients with FLI> 60 showed greater activation of the sympathetic nervous system with increased levels of MSNA compared to the control group (50±9 vs. 36±8 bursts per minute, respectively, p<0.04). At the 6-month follow-up visit, the control group had better regulation of mean systolic BP compared to the fatty liver group (66% vs 28%, respectively, p<0.001), as well as a lower SBP (123±12 vs 135±13 mmHg, p <0.04) and mean diastolic BP (83 ±9.8 vs 78±8.7 mmHg, p<0.01). Conclusions: The presence of fatty liver is associated with higher activation of the sympathetic nervous system, as reflected by MSNA, as well as difficulty in the long term regulation of blood pressure at a 6-month follow-up. These findings may partly explain the increased cardiovascular risk of hypertensive patients with NAFLD.