Heart rate variability is associated with disease severity and portal hypertension in cirrhosis

Autonomic nervous system activity in cirrhotic portal hypertension is linked to hyperdynamic circulation. Heart rate variability (HRV) is a validated noninvasive method to assess the sympathovagal balance. To investigate the correlation between HRV parameters and degree of portal hypertension, we studied a cohort of patients with cirrhosis accounting for etiology and treatments.

In this cross-sectional, observational cohort study, 157 outpatients of both sex with nonalcoholic cirrhosis were assessed by upper gastrointestinal endoscopy to search for esophagogastric varices. Twenty-four-hour electrocardiogram Holter monitoring with 3 HRV parameters measurement [SD of the NN intervals, root mean square successive difference of NN intervals, and SD of the averages of NN intervals (SDANN)] according to time-domain analysis were performed in all patients. Sixteen patients with large esophagogastric varices underwent measurements of the HVPG and assessment of HRV parameters at baseline and after 45 days on carvedilol.

The liver dysfunction, expressed by Child-Pugh class or MELD score, was directly related to root mean square successive difference of NN intervals and inversely related to SDANN. Presence of ascites was inversely related to SDANN and to SD of the NN intervals. Treatment with carvedilol had an inverse relation with SDANN. Presence and size of esophagogastric varices had an inverse relation to SDANN and SD of the NN intervals. Upon multivariate analysis the associations between SDANN and Child-Pugh class, size of varices and ascites were confirmed. In the subgroup of 16 patients undergoing HVPG measurement, pressure gradient was unrelated to heart rate and HRV parameters.

Time-domain HRV parameters in patients with cirrhosis, confirm the autonomic nervous system alteration, and their correlation to the degree of portal hypertension suggesting a role of the ANS in hepatic decompensation.