The relationship of heart rate variability with severity and prognosis of cirrhosis

Many studies have demonstrated that cirrhosis is frequently associated with autonomic dysfunction. The aim of this study was to test autonomic dysfunction in cirrhotic patients by analyzing heart rate variability (HRV), to determine whether or not the degree of autonomic dysfunction is correlated with the severity of disease, and, also, to compare the changes of HRV between survivor and nonsurvivor groups after 2-year follow-up periods. HRV was analyzed using 24-hr ECG recording in 30 cirrhotic patients and 28 normal controls. The changes in HRV parameters including mean normal-to-normal (N-N) interbeat intervals (mean NN), standard deviation of all N-N intervals (SDNN), standard deviation of the average of N-N intervals for each 5-min period over 24 hr (SDANN), root mean square succesive differences (r-MSSD; msec), and percentage of adjacent N-N intervals that are > 50 msec apart (pNN50), all as time domain parameters, were evaluated. The cirrhotic patients were also evaluated according to Child-Pugh classification scores as markers of the disease severity. The time-domain measures of HRV in cirrhotic patients were significantly reduced compared with those in the control group (for all parameters; P < 0.001). The severity of disease was associated with reduced HRV measures (for all parameters; P < 0.001). After the 2-year follow-up periods, HRV measurements in cirrhotic patients were significantly much lower in nonsurvivors than in survivors (P < 0.001 for all). We conclude that increasing severity of cirrhosis is associated with a reduction in HRV. This finding may be an indicator of poor prognosis and mortality for cirrhosis.