Pretoria

Aim To determine if there is a difference between autonomic cardiac control as measured by heart rate variability (HRV) in females with rheumatoid arthritis (RA) compared to a healthy control group. Methods The RA group (45) and control group (39) were matched for age and BMI. Three techniques were used: time domain, frequency domain and Poincarè plot analysis. All possible confounding factors were excluded and the test environment strictly regulated. Results Basal heart rate was significantly higher in the RA patients. In the supine position significant differences existed between RA patients and controls (p ≤ 0.01). Indicators of parasympathetic activity showed significantly lower variation in the RA group (RMSSD=14.70, pNN50=0.50, SD1=10.50, HF(ms2)=31) compared to controls (RMSSD=29.40, pNN50=7.8, SD1=20.9, HF(ms2)=141.00). Indicators of sympathetic variation were also significantly lower in RA patients (SD2=36.70, LF(ms2)=65) compared to controls (SD2=49.50, LF(ms2)=175). In the standing position 8 variables indicated autonomic impairment by significant differences (p≤0.01) between the groups. The response of the RA group to an orthostatic stressor showed less vagal withdrawal, [p-values for RMSSD=0.038, pNN50=0.022, SD1=0.043 and HF(ms2)=0.008 respectively]; and lower sympathetic response [p-values for SD2=0.001 and LF(ms2)<0.001] when compared to controls. Conclusions An inability of the autonomic nervous system to efficiently compensate to internal and external environmental changes may predispose RA patients to arrhythmias thereby increasing cardiovascular mortality. All 3 methods used showed the same outcome, implying decreased HRV and thus an increased risk for arrhythmias in RA patients. Evaluating the autonomic nervous system might be critical in planning management of RA patients